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  • Artikel  (123)
  • Artikel: DFG Deutsche Nationallizenzen  (123)
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  • 1
    Digitale Medien
    Digitale Medien
    Effects of radio-transmitter antenna length on swimming performance of juvenile rainbow trout (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Technological advances have lead to the production of micro radio-transmitters capable of being implanted in fish as small as c. 5 g. Although the actual tags are small, transmitters are equipped with long antennas that can increase drag and tangle in debris. We examined the effects of radio-transmitter antenna length on the swimming performance of juvenile rainbow trout, Oncorhynchus mykiss, (N = 156, mean mass = 34 g, mean fork length = 148 mm). Although we tested a variety of different antenna lengths up to a maximum of 300 mm, only the longest antenna significantly impaired swimming performance relative to control fish (P 〈 0.001). There was no difference in swimming performance between the sham (surgery, but no transmitter) and the control fish (handled, but no surgery), suggesting that the surgical procedure itself did not negatively affect the fish. Regression analysis, however, indicated that there was a significant decrease in swimming performance associated with increased antenna length (R2 = 0.11, P 〈 0.001). In addition, when held in laboratory tanks, fish with the three longest antennas (150, 225 and 300 mm) frequently became entangled with the standpipe. We suggest that researchers, under the guidance of the tag manufacturer, trim antennas to the shortest possible length required to detect fish in their specific study area. Antenna length is clearly an important issue for small fish, especially for species that inhabit complex habitats where antennas may become entangled, and where fish must attain speeds near limits of their swimming capacity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00061.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Seasonal and interannual components of intrapopulation variation in clutch size and egg size of a darter (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Previous studies have offered suggestive but sometimes conflicting glimpses at the range and patterns of seasonal and interannual variation in female darter life-history traits. The present study examined clutch-size and egg-size variation from a single Mississippi population of brighteye darters (Etheostoma lynceum), collected at regular intervals over four sequential spawning seasons. Both life-history traits were significantly correlated with body size, and they both showed significant variation within and among breeding seasons. The overall intraseasonal trends in these traits involved an increase in clutch size (CS) and a decrease in egg size from early to late periods of the spawning season. Clutch size and egg size showed a weak but significant negative correlation, which was indicative of a trade-off between the two clutch parameters. Seasonal changes in temperature appear to be related to differing patterns of seasonal variation in egg size reported in the literature for darters. Inverse seasonal shifts in egg size and CS in the brighteye darter may represent adaptive phenotypic plasticity that allows females to produce larger, competitively superior offspring early in the reproductive season when there is low supply of food for them (parental investment hypothesis) or to produce larger eggs early in the reproductive season to ensure that each egg is adequately provisioned in the face of uncertainty (bet-hedging hypothesis) if the food available for the young is unpredictable early in the season. Consistent with theoretical predictions, egg size showed less phenotypic variability than CS.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00064.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Assessment of residency and movement of the endangered bullhead (Cottus gobio) in two Flemish rivers (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Residency and movement of bullheads (Cottus gobio) were assessed by mark-recapture from November 2001 to June 2002 in two Flemish rivers [Steenputbeek (SPB), Laarse Beek (LB)]. Although the majority of the recaptured bullheads (SPB: 66%; LB: 55%) was found in their initial tagging site before the spawning season, some fish had covered distances between 10–100 m (mean: 17 ± 2 m) and 10–70 m (mean: 18 ± 7 m), respectively. During the spawning season, the proportion of fish that moved (SPB: 58%; LB: 75%) and the distances travelled (SPB: between 10 and 90 m, mean 26 ± 3 m; LB: between 30 and 260 m, mean 133 ± 3 m) were significantly larger. In addition, analysis of individual movement behaviour of multiple recaptured bullheads showed that some fish were either always resident or mobile, while others switched between both behaviours. In general, our results suggest that not all bullheads exhibit sedentary behaviour but that the populations under study consist of both stationary and mobile individuals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00065.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Habitat use and movement of river blackfish (Gadopsis marmoratus R.) in a highly modified Victorian stream, Australia (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Movement and habitat use of river blackfish (Gadopsis marmoratus R.) was studied in a highly modified central Victorian stream (Birch Creek), Australia, using radio telemetry (N = 10) and mark–recapture (N = 113) between October 2001 to May 2002, and November to December 2002 respectively. Blackfish had a small home range of 10–26 m with strong affinity to a pool. However, small movements within a pool were common which resulted in relatively large cumulative movements. At a diel scale there were no significant differences in blackfish movement between day and night (Kruskal–Wallis test, P = 0.95). Six of seven blackfish translocated 40 m upstream or downstream of their original positions returned within 48 h, suggesting strong affinity not only to a pool, but also to a small region within a pool. Blackfish utilised slow flowing (0–20 cm s−1) and deep waters (40–60 cm). Blackfish were strongly associated with the instream cover habitats of undercut banks and boulders. Significant differences were recorded in instream cover and water velocity used by blackfish between day and night (Kruskal–Wallis test, P = 〈0.01). At night blackfish used open areas with high water velocities whereas during the day blackfish used complex undercut banks with low water velocities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00068.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Body depth variation in crucian carp Carassius carassius: an experimental individual-based study (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Induced morphological defences, where individuals develop morphological structures as a response to signals from sympatric predators, are common among invertebrates. Such defences have also been reported in a freshwater fish, the crucian carp Carassius carassius. In crucian carp, the presence of piscivorous fish presumably induces the development of a deep body as a defence mechanism. We tested how the growth rate (in body depth, length and mass) of individually tagged crucian carp responds to pike Esox lucius odours and control water. In general, crucian carp exposed to pike odour grew better (both in length and mass) than control fish. The treatment crucian carp also developed deeper bodies than control crucian carp. Further, there was a strong positive relationship between individual growth rate and the rate of change in body depth and this relationship did not differ between control and treatment fish.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00048.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Reproductive roles predict sexual dimorphism in internal and external morphology of lake whitefish, Coregonus clupeaformis (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  The different reproductive roles of the sexes can predict the direction and magnitude of sexual dimorphism of external and internal morphology. Males should have enlarged structures that enhance the acquisition of mating opportunities, whereas females are predicted to have enlarged organs that are associated with the production of eggs. We tested these predictions in male and female lake whitefish, a species in which both sexes have similar overall body size and shape. After controlling for body size, male lake whitefish had significantly longer jaws and pectoral and pelvic fins, larger hearts, and more muscle than females. Sexual dimorphism in relative muscle mass may be one of the most fundamental morphological differences between males and females. Females had relatively heavier livers than males. Because the liver is important for the breakdown of fats and vitellogenesis, selection should favour an enlarged liver in females for the processing of energy and the production of large numbers of eggs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00053.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Migration of landlocked brown trout in two Scandinavian streams as revealed from trap data (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Anthropogenic barriers that may interfere or prevent fish migration are commonly found in streams throughout the distribution of salmonids. Construction of fish passages in streams is a common solution to this problem. However, the goal with fish passages is often, at least in Scandinavia, to allow Atlantic salmon (Salmo salar L.) and migratory brown trout (S. trutta L.) to get access to spawning areas above these barriers. Hence, the fish passages may often only be open during the spawning migration of salmonids (late summer to autumn). We present data, on wild brown trout migration, from two trapping systems in two Scandinavian streams showing that intra- and interstream migrations are common throughout the summer and autumn. Moreover, differences in size were found between trap-caught trout and electrofished trout where trapped trout were generally larger than electrofished trout. We suggest that the current regime with fish passages only open parts of the year can have negative effects on populations by depriving trout from the possibility to perform migrations throughout the year.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00058.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Site fidelity of spawning sockeye salmon (Oncorhynchus nerka W.) in the presence and absence of olfactory cues (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  We examined the site fidelity of spawning adult sockeye salmon (Oncorhynchus nerka) by tagging and releasing fish in the same stream reach (controls) and displacing them among different but nearby sites (c. 50 m away). Three sites – two above a stream junction (‘upper’ reach and ‘pond’) and one below (‘lower’ reach) – allowed us to compare the behavior of salmon in the presence and absence of olfactory cues and habitat similarity. Most controls of both sexes (90%) remained in the immediate vicinity of the tagging and release site. When displaced downstream, where the odors of both the upper reach and the pond were detectable, most salmon returned to their former site (65%). Displaced sockeye were more likely to return to the pond from the lower reach than from the upper one (P = 0.05), consistent with olfactory orientation and the hypothesis that salmon prefer certain habitats. Salmon displaced from the upper to the lower reach were much more likely to return than those displaced to the pond (P 〈 0.01), consistent with the role of odors in orientation and inconsistent with the habitat choice hypothesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00044.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Female-biased mortality rate and sexual size dimorphism of migratory masu salmon, Oncorhynchus masou (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  We examined whether mortality and growth during the migration phase (the lacustrine phase after smolting) differ between sexes in migratory (lake-run) masu salmon (Oncorhynchus masou) in a lacustrine population, northern Hokkaido, Japan. The sex ratio of 1+ smolts was more skewed to females than that of the returning adults in three annual cohorts examined, indicating that females have a higher mortality rate during the migration phase. Although there was no difference in smolt length between sexes, female adults were larger in body length than males of the same age: female-biased sexual size dimorphism (SSD) occurs. We suppose that breeding selection favouring a larger body size for females than for males in this population probably requires that females undertake more intensive foraging behaviour with its greater inherent risks but faster growth rates during the migration phase. It therefore seems to be likely that the selection is the ultimate cause of the female-biased mortality rate and SSD.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00043.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Diet overlap between native bigmouth sleepers (Gobiomorus dormitor) and introduced predatory fishes in a Puerto Rico reservoir (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Native fish species coexist with introduced species in Puerto Rico's freshwater systems, yet competition between these species has not been evaluated. We examined the extent of diet overlap between native bigmouth sleepers Gobiomorus dormitor and introduced largemouth bass Micropterus salmoides and peacock bass Cichla ocellaris in a Puerto Rico reservoir. Bigmouth sleepers and largemouth bass exhibited an ontogenetic shift in feeding habits, whereas peacock bass were exclusively piscivorous at all sizes collected in this study. Biologically significant diet overlap was observed between large bigmouth sleepers and largemouth bass, but not between large bigmouth sleepers and peacock bass, or between large largemouth bass and adult peacock bass. No significant diet overlap in any species combination was observed in small or medium size classes. Better understanding of the ecology of these coexisting predators should lead to improved conservation of bigmouth sleepers, and improved fisheries management for all three predatory species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00040.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    Digitale Medien
    Digitale Medien
    Spatial and temporal patterns in fish communities along the Illinois River (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Fish abundance data from a fish population study (1957–2000) on the Illinois River, IL, USA were used to assess community structure. There was considerable variability among reaches and years, but three distinct fish communities were identified encompassing both temporal and spatial aspects. Temporal community shifts in the upper half of the river created two distinct fish communities, one prior to 1983 and the other after 1983. This is believed to be in response to improved water quality, albeit the responses were delayed for several years after policy implementation. The third group (Lower River) was spatially separated from the two upper river groups. These differences may reflect a combination of water quality (e.g., pollution) and habitat issues (e.g., geomorphology), common to many regulated rivers. Fish community responses in larger rivers may have considerable temporal lags after implementation of management or restoration activities that warrant strong consideration during any planning process.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00046.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Fish assemblage recovery and persistence (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Fish assemblages from a historical (1968) pre-impoundment survey of the Bear Creek system (Tennessee River drainage) were compared with fish assemblages from recent collections to examine spatial recovery in stream fish assemblages. A positive relationship was present for species richness and distance from impoundment for recent collections but was not significant for historic collections from the same sites with distance superimposed from the impoundments. A positive relationship was also present for similarity and distance using Jaccard's Index and the Morisita Similarity Index. Recent fish assemblages were dissimilar to historical collections immediately below impoundments, but were increasingly similar at 10–20 km. The results suggest that recovery patterns for stream fish assemblages are present downstream for some types of impoundments and that remnants of the stream community persist downstream from existing impoundments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00047.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Observations of ovarian involution in the Australian grayling (Prototroctes mareana) (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract  – A 2-year study of the threatened Australian grayling, Prototroctes mareana, was undertaken to investigate its reproductive strategy in relation to river flow. Monitoring of reproductive maturity in the Barwon River in south-eastern Australia indicated that no spawning occurred in the 2 years. In both years, ovarian involution was observed in a large proportion of the sampled population; flows during this period were less than the historical average. When coupled with the historical evidence, these observations suggest that spawning coincides with increased river discharge. River regulation may inhibit spawning.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.0906-6691.2004.00020.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Effect of brown trout body size on post-stocking survival and pike predation (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  A total of 40 (20 age-3 + 20 age-4) radio-tagged hatchery-reared brown trout (Salmo trutta L.) and 40 wild radio-tagged northern pike (Esox lucius L.) were released into a regulated river. Age-3 brown trout were predicted and observed to be highly vulnerable to predation by pike (50% mortality), whereas age-4 brown trout were predicted and observed to enjoy an almost absolute size refuge from predation (5% mortality). Almost half of the fish from both age groups similarly emigrated and survived from the river within 3 days of the release. However, there was a considerable difference in survival between age groups for fish that remained in the river for a longer period. Of these, all except one age-3 brown trout were eaten by pike, whereas all but one age-4 fish survived predation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00050.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    Northern pike (Esox lucius) growth and mortality in a northern Ontario river compared with that in lakes: influence of flow (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  We measured the growth and mortality characteristics of northern pike (Esox lucius) in a northern Ontario river and examined the influence of flow on these characteristics by comparing our measurements with those estimated for a lake at the same latitude based on published studies. Pike ranged in total length from 229 to 784 mm, in mass from 70 to 4250 g, and in age from 1 to 10 years. The population showed a preponderance of 2–5-year olds, with few fish surviving beyond 7 years of age. Growth, in terms of length increase, was similar to that reported for circumpolar populations. Mean total length at 5 years of age was 577 mm, growth rate of young adults was 62.5 mm year−1, growth was isometric, longevity was 10 years of age, and the adult annual mortality rate was 49%. Growth and mortality characteristics of this riverine population were similar to those estimated for a lacustrine population at the same latitude. Flow thus had little measurable effect on the growth or mortality of pike possibly because of the overwhelming effect of other abiotic variables such as temperature, length of growing season and productivity. Consequently, growth characteristics of lacustrine populations can be used to assess the health and condition of riverine populations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00049.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    Behaviour and ecology of freshwater fish: Linking ecology and individual behaviour (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.0906-6691.2004.00035.x
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  • 17
    Digitale Medien
    Digitale Medien
    Seasonal dynamics of direct and indirect condition indices in relation to energy allocation in largemouth bass Micropterus salmoides (Lacèpede) (2004)
    Oxford UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract  – We investigated several indices (relative weight, mesentery fat, hepatosomatic index, gonadosomatic index, muscle index and visceral somatic index) of largemouth bass Micropterus salmoides (Lacèpede) as a function of season, gender and length to determine how these indices changed with energy content. Length was a significant influence in all comparisons of monthly index measurements, with the exception of the muscle index. All indices, except for the gonadosomatic index, showed few significant differences between sexes for all length groups. Generally, index values were associated with seasonal changes in prey relative abundance and temperature, and the reproductive cycle in mature fish. Total body energy was most influenced by muscle energy stores. Hepatic and gonadal energy of large, sexually mature females decreased considerably with the onset of spawning. Muscle and hepatic energy, to a lesser extent, supported gonadal development. Muscle index values closely tracked seasonal changes in muscle energy, thus providing a useful tool for evaluating seasonal growth and energy patterns. The hepatosomatic index responded to changes in body condition of small and medium fish until June, after which further increases in plumpness caused the utility of this index to decrease. The mesentery fat index provided a useful measure of stored energy available for long-term needs, relative to other energy depots. Seasonal dynamics of invasive condition indices must be considered in light of rapid increases or decreases in body weight (e.g., spawning loss of gametes).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.0906-6691.2004.00031.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    Habitat use by the African anabantid fish Ctenopoma muriei: implications for costs of air breathing (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  This study examined whether habitat use by the African anabantid fish Ctenopoma muriei is consistent with predictions relating to two costs of air breathing (surface travel and aerial predation). We predicted that C. muriei would be most abundant in habitats that minimize potential costs of air breathing. We quantified environmental correlates of C. muriei abundance within a series of wetland lagoons in Uganda and found that C. muriei was more abundant in shallow waters of the deepest lagoon, in vegetated habitats, and at a depth 15–30 cm below the surface. These locations may minimize cost of travel to the surface for aerial respiration, while maintaining a reasonable distance from the surface to avoid detection by aerial predators. In addition, we experimentally tested effectiveness of vegetative cover in reducing mortality of C. muriei by aerial predators (pied kingfishers) using enclosures with and without vegetation cover in a swamp pool. We found that the presence of vegetative cover significantly reduced susceptibility of C. muriei to predation by pied kingfishers when dissolved oxygen in the water was low and air-breathing frequency was potentially high.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.0906-6691.2004.00034.x
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  • 19
    Digitale Medien
    Digitale Medien
    Assortative mating between adjacent populations of threespine stickleback (Gasterosteus aculeatus) (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  The idea that sexual selection can lead to rapid evolution of premating isolation among independent populations (speciation) has been controversial, but is rapidly gaining acceptance among many evolutionary biologists as empirical examples accumulate. A survey of male signals and female preferences (mate recognition systems, MRSs) across the contact zone between divergent populations of threespine stickleback (Gasterosteus aculeatus) in Conner Creek, WA, revealed a spatial pattern of MRSs that is consistent with speciation via sexual selection. Females from locations that possessed melanic males preferred melanic males whereas females from populations possessing typical mosaic males (red chin, blue iris, and blue-green dorsum) preferred mosaic males. I argue that sensory drive sexual selection, acting through geographically varying spectral properties, is responsible for the observed population differences and premating isolation between the adjacent populations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.0906-6691.2004.00037.x
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  • 20
    Digitale Medien
    Digitale Medien
    Habitat use and population structure of four native minnows (family Cyprinidae) in the upper Missouri and lower Yellowstone rivers, North Dakota (USA) (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  In 1997 and 1998, sampling was conducted on the Missouri and Yellowstone rivers, North Dakota, to obtain information on the distribution, abundance, and habitat use of the flathead chub (Platygobio gracilis Richardson), sicklefin chub (Macrhybopsis meeki Jordan & Evermann), sturgeon chub (Macrhybopsis gelida Girard), and western silvery minnow (Hybognathus argyritis Girard), four declining fish species (family Cyprinidae) native to the Missouri River basin, USA. The study area consisted of four distinct river segments near the confluence of the Missouri and Yellowstone rivers – three moderately altered segments that were influenced by a main-stem dam and one quasi-natural segment. One moderately altered segment was located at the confluence of the two rivers (mixing-zone segment (MZS)). The other two moderately altered segments were in the Missouri River adjacent to the MZS and extended up-river (above-confluence segment (ACS)) and down-river (below-confluence segment (BCS)) from this segment. The quasi-natural segment (Yellowstone River segment (YRS)) extended up-river from the MZS in the Yellowstone River. Catch rates with the trawl for sicklefin chub and sturgeon chub and catch rates with the bag seine for flathead chub and western silvery minnow were highest in the BCS and YRS. Most sicklefin and sturgeon chubs were captured in the deep, high-velocity main channel habitat with the trawl (sicklefin chub, 97%; sturgeon chub, 85%), whereas most flathead chub and western silvery minnow were captured in the shallow, low-velocity channel border habitat with the bag seine (flathead chub, 99%; western silvery minnow, 98%). Best-fit regression models correctly predicted the presence or absence of sicklefin chub, flathead chub, and western silvery minnow more than 80% of the time. Sturgeon chub presence and absence were predicted correctly 55% of the time. Best-fit regression models fit to fish number data for flathead chub, sicklefin chub, and sturgeon chub and fish catch-per-unit-effort (CPUE) data for flathead chub also provided good fits, with R2 values ranging from 0.32 to 0.55 (P 〈 0.0001). The higher density and catch of the four native minnows in the YRS and BCS suggest that these two segments are better habitat than the ACS and MZS.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.0906-6691.2004.00036.x
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  • 21
    Digitale Medien
    Digitale Medien
    Analysis of the spawning stock–recruitment relationship of vendace (Coregonus albula (L.)) with evaluation of alternative models, additional variables, biases and errors (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Spawning biomass and recruitment data for vendace from a central Finnish lake were analysed by fitting various recruitment models and comparing the fits statistically. The compensatory models of Ricker, Cushing and Beverton & Holt fitted the data better than the H0 hypothesis of constant proportionality, but model and parameter uncertainties were high. Additional variables were included in an attempt to reduce uncertainties. Heavy wind forcing during the first month after hatching of larvae reduced the recruitment success. For the Ricker and the Cushing models, recruitment seemed to be also negatively associated with the density of the previous year-class. The r2 increased considerably with inclusion of these additional variables, but the precision of model parameters remained low. Monte Carlo simulation of a vendace stock was applied to evaluate the interference of biases from the measurement error (ME) and time series error (TSE) in the analysis. Especially in the case of the Cushing model, compensatory density dependence can be overestimated severely. Increasing the number of observations decreases the biases in some cases. In view of potential biases and uncertainties, a precautionary management policy is recommended.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.0906-6691.2004.00041.x
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  • 22
    Digitale Medien
    Digitale Medien
    Vertical distribution patterns of zooplanktivorous fish in a shallow, eutrophic lake, mediated by water transparency (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  The vertical distribution pattern (VDP) of fish at shallow sites in eutrophic lake – Lake IJssel, the Netherlands – as affected by water transparency, was examined. The pattern was assessed by pair trawling at three depths and by hydroacoustics from June to August. Water transparency was estimated by light intensity and Secchi depth measurements. Hydroacoustics showed that fish were more dispersed at night than during the day. European smelt, (Osmerus eperlanus) and young-of-the-year Eurasian perch (Perca fluviatilis) comprised 97% of the fish in numbers. European smelt concentrated near the surface, at light intensities of 〉200 µW · cm−2 when the water was turbid, and near the bottom when the water was clear (Secchi depth 〉 1.2 m). We concluded that low water transparency over-ruled the light sensitivity of European smelt, and caused European smelt to stay higher in the water column.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.0906-6691.2004.00042.x
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  • 23
    Digitale Medien
    Digitale Medien
    Trophic structure of fish assemblages from Mamoré River floodplain lakes (Bolivia) (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  The fish assemblage of the floodplain of the Mamoré River (Bolivia) was estimated in eight lakes, corresponding to four habitat types, situated on an environmental gradient related to the river distance: lakes situated near the river, in the forested floodplain, at the floodplain edge and lakes isolated in the savanna. This paper documents the diet of 71 fish species (among the 140 recorded) and compares the taxonomic and trophic structure of fish assemblages between four lake types. The diet analysis was conducted to determine five trophic guilds: algivores/iliophages, herbivores, zooplanktivores, invertivores and piscivores. The taxonomic and trophic structures of the fish assemblages were not similar in the different lake types of the Mamoré River. The trophic structure of assemblages showed a coarse pattern of dominance of algivores/iliophages and invertivores, but different situations were observed in relative abundance of the trophic groups in relation to the spatial position of the lakes (except for piscivores). Lakes close to the river appeared more favourable to the microphages (algivores/iliophages, zooplanktivores) although remote lakes appeared more favourable to the macrophages (invertivores, herbivores). These results support the general idea that fish distribution follows a pattern linked to the ecology of the species, and related to environmental characteristics of the lakes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00055.x
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  • 24
    Digitale Medien
    Digitale Medien
    Diet overlap and consumption patterns suggest seasonal flux in the likelihood for exploitative competition among piscivorous fishes (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Competition, both intraspecific and interspecific, among piscivorous fishes (predators) may be more pronounced in reservoirs because of the artificial nature of these systems and the continuous anthropogenic influences that may not allow natural processes to regulate their densities. Most studies attempting to measure the extent of competition are based on predator–prey balance indices that are annual snapshots and do not account for seasonal changes. We sought to identify times during the year when intra- and interspecific exploitative competition for prey was most likely among dominant predators in a large reservoir of the south-eastern United States. The possibility of interspecific competition was measured by examining the seasonal extent of diet overlap based on samples of stomach contents. The likelihood or severity of this competition was indexed by how well predators met their energy needs. We found predators were realising less of their energy requirements during spring and autumn, and diet analyses showed predators overlapped substantially in their use of prey during those seasons. Thus, exploitative competition was most likely or severe during spring and autumn; furthermore, this competition had the potential to be interspecific as evidenced by resource overlap.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00066.x
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  • 25
    Digitale Medien
    Digitale Medien
    Quantifying the effectiveness of regional habitat quality index models for predicting densities of juvenile Atlantic salmon (Salmo salar L.) (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  The suitability of using regional Habitat Quality Index (HQI) models for predicting distributions of juvenile salmon (Salmo salar L.) was examined using data acquired from selected rivers within Québec, Canada. Regional HQI models were derived by identifying preferences of salmon fry and parr for the habitat properties of flow velocity, water column depth and granulometric index (an index of substrate size) for groups of rivers. These were compared with local HQI models, derived from preferences for habitat properties within individual rivers. Relationships between HQI values and densities of juvenile salmon were established through the use of nonlinear regression. In all cases, the regional HQI models were less effective for explaining distributions of juvenile salmon than local HQI models based on individual rivers. Regional HQI models were relatively ineffective when the habitat characteristics of the river to which they were applied differed greatly from the characteristics of the other rivers within the region. It is inferred that the relationship between the effectiveness of the regional HQI model and the difference in characteristics between individual rivers and those of the region may be used in an a priori determination of whether a regional HQI may be applied effectively to any given river.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00069.x
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  • 26
    Digitale Medien
    Digitale Medien
    Acknowledgements to reviewers (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00078.x
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  • 27
    Digitale Medien
    Digitale Medien
    Spatial and quantitative patterns of movement in large bull trout (Salvelinus confluentus) from a watershed in north-western British Columbia, Canada, are due to habitat selection and not differences in life history (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Movement and habitat use by bull trout (Salvelinus confluentus) was examined using radio telemetry in the Morice River watershed, north-western British Columbia, between April 2000 and November 2001. Bull trout principally utilised mainstem habitat. Throughout the watershed, little movement was observed during the winter months. From June to September, movement increased and was correlated with migration into tributaries. We directly observed spawning bull trout only in tributaries of the Morice River and never in the mainstem. Many of the fish (N = 48) migrated to the nearest potential spawning sites, but a few fish (N = 7) made extensive migrations to other regions of the watershed to spawn. Fish that spawned in both years of the study returned to the same spawning location. Variation in spatial and movement data, therefore, appears to be linked to availability of suitable habitat and not differences in life history that have been observed in large bull trout.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00071.x
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  • 28
    Digitale Medien
    Digitale Medien
    Sex-specific growth pattern during early life history in masu salmon, Oncorhynchus masou (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  To examine whether or not sex-specific growth occurs in fry of masu salmon Oncorhynchus masou, 90 half-sibling fry chosen from three different classes of egg size (small, medium and large) and emergence time (period from fertilisation to first feeding; early, middle and late) were raised in a tank for 60 days. In all four replications, male fry grew faster than females. The difference in growth between sexes was greater among siblings hatched from larger eggs. Fast-growing, young male masu salmon show a precocious form that tends to mature without migrating to sea. Slower growing males tend to show the anadromous form, which is only shown in females. Sex-specific life histories may influence the sex-specific growth patterns during early life history.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00051.x
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  • 29
    Digitale Medien
    Digitale Medien
    Effects of lipid extraction on stable carbon and nitrogen isotope analyses of fish tissues: potential consequences for food web studies (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  We examined whether solvent-based lipid extractions, commonly used for stable isotope analysis (SIA) of biota, alters δ15N or δ13C values of fish muscle tissue or whole juvenile fish. Lipid extraction from muscle tissue led to only small (〈1‰) isotope shifts in δ13C and δ15N values. By contrast, ecologically significant shifts (+3.4‰ for δ13C and +2.8‰ for δ15N) were observed for whole juvenile fish. Sample variance was not affected by lipid extraction. For tissue-specific SIA, two sample aliquots may be required: a lipid-extracted aliquot for stable carbon isotope analysis when differing lipid content among tissues is a concern, and a nonextracted aliquot for δ15N determination. Whole organism SIA is not recommended because of the mix of tissues having different turnover times; for very small fish, we recommend that fish be eviscerated, decapitated, and skinned to minimise differences with samples of muscle tissue.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00056.x
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  • 30
    Digitale Medien
    Digitale Medien
    Competition for food between Eurasian perch (Perca fluviatilis L.) and ruffe (Gymnocephalus cernuus [L.]) over different substrate types (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Food consumption by Eurasian perch (Perca fluviatilis L.) and ruffe (Gymnocephalus cernuus [L.]) was studied in single and mixed-species treatments in the laboratory, where alternative food resources, chironomids and zooplankton, were offered simultaneously. The effects of structural complexity, which was represented by substrate grain size, and of feeding level on food consumption were analysed. Across all experiments, the outcome of competition between perch and ruffe depended on food abundance and on the structural complexity of the environment. Perch and ruffe both changed their food consumption in the presence of a heterospecific competitor. With high food supply, perch consumed more benthic food than ruffe. With low food supply, the consumption of perch decreased strongly, while that of ruffe remained high on fine sediment. Under all conditions tested, the mechanism of competition appeared to be of interference rather than of exploitative nature. It is suggested that with decreasing lake productivity caused by re-oligotrophication, habitat shifts of both species will occur, which will alleviate interspecific competition. Ruffe will forage over fine sediment and perch over coarse sediment, whereby both species will achieve the highest foraging efficiency under conditions of low food supply.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00059.x
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  • 31
    Digitale Medien
    Digitale Medien
    Seasonal changes of liver glycogen content and condition factor of wild Atlantic salmon parr in a sub-arctic river (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Mean liver glycogen content of 1–4-year-old Atlantic salmon parr varied from 0.5 to 9.5% (of fresh liver mass) and condition factor (CF) from 0.66 to 0.85 in the sub-arctic River Teno system in northern Finland during 2 years of study. There were no significant differences in liver glycogen contents of different age groups as there were in CF. However, there were seasonal differences in liver glycogen content and CF of the wild parr. The lowest liver glycogen contents were observed in July and the highest in September and December whereas the lowest CFs were observed in May and the highest in July.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00067.x
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  • 32
    Digitale Medien
    Digitale Medien
    Modelling the life-history variation of Arctic charr (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  A model based on proximate considerations of life histories of Atlantic salmon, Salmo salar, was examined for its applicability to fit the variation in life-history of wild Arctic charr, Salvelinus alpinus, based on a qualitative assessment of information related to growth and lipid dynamics of Arctic charr. The original salmon model is discussed in context of modifications required to account for added complexities in the life history of Arctic charr in relation to anadromy versus residency. A study from North Norway shows that individual charr that emigrate from the lakes to the sea, maintain a high growth rate in the lake in late summer and early autumn compared with resident fish. Their relatively low lipid level in autumn combined with a high rate of change of lipid during winter was associated with postponement of maturation in the anadromous individuals. Individuals that remain resident in the lake arrested growth in autumn. Their high lipid level in autumn combined with a low rate of change of lipid during winter was associated with maturation the following summer, without emigration from freshwater. Results from this and other related studies show similarities with the model derived from lipid and growth dynamics of Atlantic salmon. The adjusted charr model illustrates possible proximate explanations for the high variation in life-history strategies of Arctic charr. However, the model does not account for the characteristic return migration of immature charr into freshwater several weeks after their entry to the sea. The proximate physiological stimulus for this movement of immature fish is not entirely clear.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00070.x
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  • 33
    Digitale Medien
    Digitale Medien
    Editorial (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00077.x
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  • 34
    Digitale Medien
    Digitale Medien
    Energy use in spawning Atlantic salmon (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  We studied some of the factors that might influence energy use in spawning Atlantic salmon (Salmo salar). Single females were placed into an experimental channel with either one or three males, after which spawning was monitored continuously. Male status was confirmed using genetic parentage analysis. Daily fat loss was monitored with the Torry Fish Fatmeter and validated through biochemical analyses. Several comparisons were in the expected direction but not statistically significant and therefore require further study: daily fat loss appeared higher for dominant males relative to subordinate males and in the three-male treatment relative to the one-male treatment. Most of the variation among individuals remained unexplained, suggesting that several as yet unknown factors strongly influence fat loss in spawning salmon. A large and significant effect was that daily fat loss was higher for females than for males, a difference that might contribute to the shorter spawning duration typical of females.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00045.x
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  • 35
    Digitale Medien
    Digitale Medien
    Effects of constant and cyclical thermal regimes on growth and feeding of juvenile cutthroat trout of variable sizes (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  The effects of constant (12, 18, and 24 °C) and cyclical (daily variation of 15–21 and 12–24 °C) thermal regimes on the growth and feeding of Lahontan cutthroat trout (Oncorhynchus clarki henshawi) of variable sizes were examined. Higher constant temperatures (i.e., 24 °C) and more variable daily temperatures (i.e., 12–24 °C daily cycle) negatively affected growth rates. As fish mass increased (from 0.24 to 15.52 g) the effects of different thermal regimes on mass growth became more pronounced. Following 14 days exposure to the thermal regimes, feeding rates of individual fish were assessed during acute exposure (40 min) to test temperatures of 12, 18, and 24 °C. Feeding rate was depressed during acute exposure to 24 °C, but was not significantly affected by the preceding thermal regime. Our results indicate that even brief daily exposure to higher temperatures (e.g., 24 °C) can have considerable sublethal effects on cutthroat trout, and that fish size should be considered when examining the effects of temperature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00052.x
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  • 36
    Digitale Medien
    Digitale Medien
    Use of stable isotopes to distinguish farmed from wild Atlantic salmon, Salmo salar (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Stable isotopes of carbon and nitrogen (δ13C and δ15N) were examined in wild and aquaculture origin Atlantic salmon, Salmo salar, to evaluate their utility to identify escaped farmed fish. Samples of muscle tissue obtained from wild Conne River, Newfoundland, salmon were significantly more enriched in nitrogen (δ15N: mean = 12.75; SD ± 0.38‰) but depleted in lipid corrected carbon (δ13C′: mean = −20.51; SD ± 0.23‰) by comparison with aquaculture specimens obtained from Bay d'Espoir, Newfoundland (δ15N = 10.96 ± 0.19‰; δ13C′ = −19.25 ± 0.17‰) resulting in a complete separation of the two groups. Aquaculture specimens differed in δ13C′ from analyses of commercial salmon diet by 0.24‰, within the enrichment range associated with trophic transfers, while the δ15N values in salmon muscle were enriched by 5.01‰. Although differences occurred in direct comparisons of white muscle and adipose tissue (N = 49), the average δ13C′ and δ15N signatures varied in absolute amounts by only 0.5‰, supporting the use of adipose tissue as a nonlethal means to determine isotopic signatures of Atlantic salmon.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00057.x
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  • 37
    Digitale Medien
    Digitale Medien
    Longitudinal segregation of Astyanax janeiroensis in Rio Ubatiba: a Neotropical stream of south-east Brazil (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  In this study, we explored patterns of size and abundance of Astyanax janeiroensis in Rio Ubatiba (Rio de Janeiro, south-east Brazil) in relation to reproduction. A. janeiroensis broadcast their eggs in the water column throughout the year. Samples at seven sites conducted every second month from July 1994 to August 1995 revealed a predominance of larger adult specimens upstream and immature juveniles downstream. We hypothesize that upstream movements of adult individuals is a response to drifting of eggs and larvae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00062.x
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  • 38
    Digitale Medien
    Digitale Medien
    Assessing the potential for fish predation to impact zebra mussels (Dreissena polymorpha): insight from bioenergetics models (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Rates of annual food consumption and biomass were modeled for several fish species across representative rivers and lakes in eastern North America. Results were combined to assess the relative potential of fish predation to impact zebra mussels (Dreissena polymorpha). Predicted annual food consumption by fishes in southern waters was over 100% greater than that in northern systems because of warmer annual water temperatures and presumed increases in metabolic demand. Although generally increasing with latitude, biomasses of several key zebra mussel fish predators did not change significantly across latitudes. Biomasses of some less abundant fish predators did increase significantly with latitude, but increases were not of the magnitude to offset predicted decreases in food consumption. Our results generally support the premise that fishes in rivers and lakes of the southern United States (U.S.) have inherently greater potential to impact zebra mussels by predation. Our simulations may provide a partial explanation of why zebra mussel invasions have not been as rapid and widespread in southern U.S. waters compared to the Great Lakes region.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00033.x
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  • 39
    Digitale Medien
    Digitale Medien
    Microhabitat use by Iberian nase Chondrostoma polylepis and Iberian chub Squalius carolitertii in three small streams, north-west Portugal (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Microhabitat use of Iberian nase Chondrostoma polylepis (Steindachner 1865) and Iberian chub Squalius carolitertii (Doadrio 1988) was studied in three small streams of the Lima basin, north-west Portugal. Measurements were made for 210 and 248 individuals, respectively, distributed in two size classes, based on fish ages, during winter, spring, summer and autumn 1998. Both species moved to shallow and slow-flowing microhabitats in summer and autumn, but this mainly reflected seasonal variation in microhabitat availability. Larger individuals of both species used deeper and lower percentage cover areas than smaller conspecifics, however significant ontogenetic differences were only found for water velocity. Different patterns of nonrandom microhabitat use were displayed by both cyprinids. Larger I. nase were in deeper and more discovered waters than those available in the habitat, whereas I. chub was over-represented in slow-flowing areas. There was no evidence of interspecific competition for microhabitat, therefore it is unlikely that spatial resource was limited during the present study.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00054.x
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  • 40
    Digitale Medien
    Digitale Medien
    Alpine and Apennine barriers determining the differentiation of the rudd (Scardinius erythrophthalmus L.) in the Italian peninsula (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  A phylogeographic study of rudd Scardinius erythrophthalmus L. (Pisces: cyprinidae) was addressed to determine the differentiation of Italian populations in relation to the presence of mountain barriers, which identify two biogeographic districts (Padano-Venetian, Tuscano-Latium). At this scope, 409 bp long sequences of mtDNa cytochrome b gene were obtained from Italian and central European samples. Italian rudds phylogeny showed low level of divergence which although resulted from the central European haplotypes. The genetic structure of haplotypes in the studied districts revealed a significant recent fragmentation event. The Padano-Venetian populations showed patterns of past range expansion caused by the specie dispersion by river connections occurred during Pleistocene. This pattern provides evidence for (i) the role of Alps as a barrier for rudd dispersion; (ii) a significant genetic structure among the studied districts related to recent isolation events by the Apennine barrier; (iii) the role of Pleistocene sea level variations in determining phylogeography of the Padano-Venetian populations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00060.x
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  • 41
    Digitale Medien
    Digitale Medien
    Parasitism, condition and number of front head breeding tubercles in roach (Rutilus rutilus L.) (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  In a previous study on the male roach, Rutilus rutilus, we found a positive correlation between sexual ornamentation, breeding tubercles (BTs) on lateral sides and parasite resistance. As a continuation of that study, we examined another measure of sexual ornamentation – number of BTs on front head – of male roach from five populations. BTs on head correlated positively with fish size in two populations and with condition in one population, but not with parasite resistance (proportion of dead parasites) in any of the populations. Moreover, head BTs correlated negatively with the number of two parasite species (Rhipidocotyle campanula and Myxobolus mülleri) in two populations, but positively with the number of a third parasite (Raphidascarus acus) in one population. In addition, a negative correlation with spleen size was found in one population. The present results suggest that head BTs of male roach – although the patterns vary between populations – may signal condition and parasite load, but not resistance, in contrast to lateral BTs. Therefore, our results are in line with the hypothesis of multiple-message sexual ornaments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00039.x
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  • 42
    Digitale Medien
    Digitale Medien
    Reproduction biology of pikeperch (Sander lucioperca (L.)) – a review (2003)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 12 (2003), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  The present review focuses on the reproduction biology of pikeperch (Sander lucioperca (L.)). Aspects like maturity, fecundity, spawning migrations, spawning habitats, onset of spawning, and development time of eggs were reviewed. The onset of maturity is reached at younger age in southern than northern populations due to higher growth rate in the south. Males mature at smaller size and are on average younger than females. Absolute fecundity is closely related to the length and weight, but no clear relationship could be found between relative fecundity and length. Statistically significant relationships were found between the onset of spawning and latitude, and between the duration of the development time of eggs and stable water temperature. Near the southern limits of distribution, the onset of spawning is in February while near the northern limits it is in June. The interannual variability in fecundity and in the onset of maturity and further the factors affecting them have not been studied much. Furthermore, it is not known whether these variations could affect the population dynamics of pikeperch. Little is also known about the actual spawning behaviour of pikeperch in natural habitats. This is probably due to the typical spawning habitats located at 1–3 m depth in waters with high turbidity and low visibility. Even though the homing behaviour to the same spawning areas is well developed in adults, it is not known whether the adults were actually born in the same area.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2003.00005.x
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  • 43
    Digitale Medien
    Digitale Medien
    Habitat–predator association and avoidance in rainbowfish (Melanotaenia spp.) (2003)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 12 (2003), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  The ability to recall the location of a predator and later avoid it was tested in nine populations of rainbowfish (Melanotaenia spp.), representing three species from a variety of environments. Following the introduction of a model predator into a particular microhabitat, the model was removed, the arena rotated and the distribution of the fish recorded again. In this manner it could be determined what cues the fish relied on in order to recall the previous location of the predator model. Fish from all populations but one (Dirran Creek) were capable of avoiding the predator by remembering either the location and/or the microhabitat in which the predator was recently observed. Reliance on different types of visual cues appears to vary between populations but the reason for this variation remains elusive. Of the ecological variables tested (flow variability, predator density and habitat complexity), only the level of predation appeared to be correlated with the orientation technique employed by each population. There was no effect of species identity, which suggests that the habitat that each population occupies plays a strong role in the development of both predator avoidance responses and the cues used to track predators in the wild.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2003.00007.x
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  • 44
    Digitale Medien
    Digitale Medien
    Body shape variation within and among three species of darters (Perciformes: Percidae) (2003)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 12 (2003), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Using geometric morphometric (GM) techniques, we quantified intra and interspecific variation in female body shape using five collections each of Etheostoma caeruleum Storer, Etheostoma nigrum Rafinesque, and Etheostoma stigmaeum (Jordan). Nested multivariate analysis of variance showed significant variation in body shape among populations (Wilks' Λ = 0.0687, F144,7585.1 = 19.35, P 〈 0.0001), as well as among species (Wilks' Λ = 8.7 × 10−6, F24,2 = 28.18, P = 0.0348). Etheostoma caeruleum displayed greater body depth relative to both E. nigrum and E. stigmaeum, whereas E. nigrum displayed a compressed arrangement of mid-body landmarks relative to both E. stigmaeum and E. caeruleum. The broader implications of these findings highlight the value of geometric morphometrics as both an exploratory and analytical approach. Conclusions drawn from comparisons among moderately differentiated darter species in future studies of body size and shape are likely robust to intraspecific variation within species, and will permit more rigorous investigations into the ecomorphology of these benthic stream fishes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2003.00008.x
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  • 45
    Digitale Medien
    Digitale Medien
    Assemblage structure and habitat use of fishes in a Central European submontane stream: a patch-based approach (2003)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 12 (2003), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  We examined macrohabitat patch level assemblage composition and habitat use patterns of fishes over four seasons in a second-order submontane stream (Danube drainage, Hungary). Rainfall data indicated that our study included both high- and low-water periods, and hence our results may be applicable to broader time scales. Principal component analysis of physical habitat data from 13 macrohabitat patches indicated that these patches represented a riffle-pool continuum. Correspondence analysis of fish assemblage structure data from these patches identified a continuum in assemblage composition that was positively correlated with the habitat continuum. The riffle fauna was dominated by stone loach (Barbatula barbatula), whereas chub (Leuciscus cephalus) were most abundant in pool patches. We detected little evidence of seasonality in either fish assemblage structure or habitat use. Fish density did not differ significantly among macrohabitat patches in two (summer and autumn 1999) of three seasonal samples, although riffle patches displayed significantly higher fish abundance in late spring 2000. This difference primarily was due to higher abundance of juvenile stone loach in riffles. Two species, stone loach and minnow (Phoxinus phoxinus), displayed generalized habitat use patterns, whereas chub and rare species (i.e., gudgeon, Gobio gobio; dace, Leuciscus leuciscus; Barbus petenyi; and burbot, Lota lota) were significantly over-represented in pool habitats. We hypothesized that pool specialists (i.e., chub and rare species) were responding primarily to the increased depth of these habitats. Nevertheless, our data did not demonstrate the presence of separate pool and riffle habitat guilds. In conclusion, we believe that our understanding of stream fish ecology will be greatly facilitated by use of a ‘patch-based approach’.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2003.00009.x
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  • 46
    Digitale Medien
    Digitale Medien
    Size-related changes in habitat selection by larval grayling (Thymallus thymallus L.) (2003)
    Oxford UK : Munksgaard International Publishers
    Ecology of freshwater fish 12 (2003), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract  – In a medium-sized river in northern Finland, larval grayling shifted with growth from shallow habitats with slow velocities, fine substrata and abundant vegetation cover to deeper sites with swifter velocities, coarse substrata and sparse vegetation cover within 3 weeks. Small (17–21 mm) larvae preferred water depths 10–30 cm, substrata dominated by mud or sand (〈2 mm), 10–70% vegetation cover and water velocities 〈10 cm · s−1. Middle-sized (22–25 mm) larvae preferred 30–90 cm depths, sandy substrata, 〈40% vegetation cover and velocities 〈10 cm · s−1. Large (26–31 mm) larvae preferred 〉50 cm depths, substrata dominated by sand or boulders, 〈20% vegetation cover and 10–50 cm · s−1 velocities. The strict habitat requirements of the smallest larval group suggest that these habitats, in particular, are important to the early survival of grayling.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2003.00013.x
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  • 47
    Digitale Medien
    Digitale Medien
    Ontogenetic changes in the diet of the black-stripe minnow Galaxiella nigrostriata (Shipway, 1953) (Galaxiidae) and the salamanderfish Lepidogalaxias salamandroides (Mees, 1961) (Lepidogalaxiidae) (2003)
    Oxford UK : Munksgaard International Publishers
    Ecology of freshwater fish 12 (2003), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Similarities in the diets of larval, juvenile and adult black-stripe minnow (Galaxiella nigrostriata) and salamanderfish (Lepidogalaxias salamandroides), collected from ephemeral pools in south-western Australia during the mid-wet, late-wet and dry seasons, were assessed. During the mid-wet season, both intra- and interspecific competition for a diminishing food supply was minimised through differences in prey utilisation by the various developmental stages of both species. During the late-wet season, the pools contained only juvenile G. nigrostriata and juvenile and adult L. salamandroides, the diets of which were vastly different. A shift towards terrestrial fauna by G. nigrostriata and the ingestion of greater proportions of larger benthic prey taxa by L. salamandroides minimised interspecific competition for food at a time when densities of zooplanktors were rapidly declining. Timing differences in the onset of aestivation ensures that no interspecific competition for food occurs during the dry season.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2003.00012.x
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  • 48
    Digitale Medien
    Digitale Medien
    Movement of fish between a river and its backwater: diel activity and relation to environmental gradients (2003)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 12 (2003), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract –  Movements of fish, in particular roach Rutilus rutilus, perch Perca fluviatilis, rudd Scardinius erythrophthalmus, bleak Alburnus alburnus and chub Leuciscus cephalus (age ≥ 1+) in relation to environmental variables were examined between the River Morava, Czech Republic, and a rehabilitated former meander. Data were taken over seven 24-h periods in April–June 1997 using two back-to-back traps. Of 170 fish captured, 70% moved from the backwater to the river. Diel activity differed between sampling dates, but overall bleak, roach and chub moved mainly between dusk and dawn, whereas perch moved throughout most of the day. Rudd showed bi-modal (mid-day, midnight) activity. However, avoidance behaviour could have biased results for species known to be wary of traps. Water level changes, temperature and illumination were among the main environmental factors influencing fish movement, along with spawning migrations relevant for most species. In all specimens, over 65% individuals captured were ready to spawn. Most of them, except for perch, were moving out of the backwater towards the river.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2003.00014.x
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  • 49
    Digitale Medien
    Digitale Medien
    Relationships between trout habitat use and woody debris in two southern New England streams (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – In-stream habitat was measured and trout density was estimated in Merrick Brook (105 habitat units) and the Tankerhoosen River (135 habitat units), Connecticut to determine relationships between habitat use of brook trout Salvelinus fontinalis and brown trout Salmo trutta and woody debris. In each habitat unit, woody debris was inventoried, and length, width, depth, area, width : depth ratio and undercut bank area were estimated. Trout abundance was estimated by snorkeling. Multiple regression was used to test relationships between trout density and principal components describing habitat unit variables. In Merrick Brook, habitat unit size and shape explained most of the variability in density of brook trout (〈130 and ≥130 mm) and brown trout (〈150 mm) among habitat units, although principle components describing large woody debris or fine woody debris contributed significantly to variations in density of brook trout (≥130 mm) and brown trout (〈150 and ≥150 mm). In the Tankerhoosen River, fine woody debris explained most of the variability in density of brook trout (〈130 and ≥130 mm), followed by habitat unit size and shape. Both large woody debris and fine woody debris contributed significantly to variations in density of brown trout (≥150 mm). These results suggest that woody debris is an important component of wild trout habitat above that provided by habitat unit shape and size alone.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00016.x
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  • 50
    Digitale Medien
    Digitale Medien
    Micro-scale distribution of brown trout: an opportunity for kin selection? (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Fourteen microsatellite loci were used to analyse the degree of relatedness between and within cohorts of stream-living brown trout (Salmo trutta L.). Differences in degree of relatedness were found between cohorts with mature and older having the highest intracohort relatedness. The higher genetic relatedness among the mature and older trout is interpreted as indications of clustering of related mature and older trout prior to spawning in the vicinity of spawning grounds. Young-of-the-year trout showed a lower degree of association with related trout of the same cohort than did mature and older trout. It is argued that the clustering of mature and older trout may facilitate kin selection and that the low degree of association among related young-of-the-year trout could be explained by juvenile fish avoiding competition for territories with related individuals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00017.x
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  • 51
    Digitale Medien
    Digitale Medien
    Effects of kinship on growth and movements of brown trout in field enclosures (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract  – The effect of kinship on growth and use of space by individually PIT-tagged 1+ brown trout was studied for 11 weeks in eight stream enclosures. Each enclosure consisted of two sections, separated by a region containing PIT-detecting antennae, which enabled us to measure use of sections by all individuals. Two types of sibling groups were tested, a single sibling group, F1, consisting of four individuals that were reared together in hatchery tank ‘a’ (F1a) plus four additional siblings of the same family but raised in hatchery tank ‘b’ (F1b), and a mixed sibling group, consisting of four F1a individuals plus four siblings from a second family, F2. Based on kin theory and earlier laboratory studies, we expected that growth of the F1a individuals in the single sibling group to be greater than that of F1a individuals in the mixed family sibling group, but instead we found just the opposite. The variance of growth did not differ between treatments. Nor was there a difference in time F1a individuals spent together when they were in mixed versus single sibling groups. We did find that F1a individuals changed habitat more frequently than F2 individuals in the mixed sibling group but less frequently than F1b in the single sibling groups. Thus, our predictions based on kin theory for growth and behavior of brown trout were not supported by our data, and we suggest that the role of kin recognition for the ecology of salmonids deserves further attention.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00018.x
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  • 52
    Digitale Medien
    Digitale Medien
    Prey size selection in piscivorous pikeperch (Stizostedion lucioperca) includes active prey choice (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Knowledge of the mechanisms behind prey selection in piscivorous fish is important for our understanding of the dynamics of freshwater systems. Prey selection can involve active predator choice or be a passive process. We experimentally studied size-selectivity in pikeperch, feeding on roach and rudd. When given a choice of different prey sizes, pikeperch selected small prey. Passive selection mechanisms (encounter rate, capture success and satiation) could not fully explain the pattern of diet choice. Instead, behavioural analysis revealed that the pikeperch actively selected small-sized prey. Optimal foraging theory, predicting that predators will choose prey sizes giving highest energy return per time spent foraging, is assumed to explain active choice. We measured handling times for a range of prey sizes and found that the most profitable sizes were also the chosen ones, both in experiments and in the field. This suggests that pikeperch choose their prey to maximise energy intake per unit time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00019.x
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  • 53
    Digitale Medien
    Digitale Medien
    Long-term variation in piscivory in a brown trout population: effect of changes in available prey organisms (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – The piscivorous behaviour in a brown trout (Salmo trutta L.) population was studied in four discrete periods over seven decades (1917–94) in the hydroelectric reservoir Tunhovdfjord in Norway established in 1919. Piscivorous brown trout were extremely scarce prior to the introduction of two fish species Arctic charr (Salvelinus alpinus L.) and European minnow (Phoxinus phoxinus L.) in the 1920s. Brown trout started eating minnow at 17 cm and Arctic charr at 22 cm of length. In the 1950s, the brown trout predated extensively (60% of analysed trout) on Arctic charr and minnow. During the next four decades, the incidence of piscivorous brown trout declined to 15%, whereas the frequency of brown trout eating Arctic charr remained constant at 10%. The growth pattern, expressed as back-calculated length, demonstrated similarity in three periods (1920s, 1960s and 1990s) and improved growth in the 1950s. The improvement was addressed the impoundment of a reservoir upstream. We did not find any marked change in growth rate due to piscivority, but coefficient of variance of back-calculated lengths indicated significant variation in individual growth in age group ≥6 years from 1950 onwards. We accredit this variation to the rise of piscivorous brown trout.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00020.x
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  • 54
    Digitale Medien
    Digitale Medien
    Interpopulation comparison of size and age at smolting of white-spotted charr, Salvelinus leucomaenis (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – The relationships between size and age at smolting and juvenile growth rates were examined for 13 populations of white-spotted charr (Salvelinus leucomaenis). Mean smolt length (ranging 142–210 mm in fork length) and smolt age (2.4–3.7 years) varied significantly among populations and there was a significant negative relationship between smolt length and age. Mean smolt length was positively correlated with mean specific growth rate from age 0 to 1 year, whereas mean smolt age was negatively correlated with specific growth rate. The present study shows that the freshwater environment conditions operating on juvenile growth are important for moulding the phenotypic characteristics of size and age at smolting.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00021.x
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  • 55
    Digitale Medien
    Digitale Medien
    The effects of fluvial processes and habitat heterogeneity on distribution, growth and densities of juvenile Atlantic salmon (Salmo salar L.), with consequences on abundance of the adult fish (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – The required freshwater habitats of juvenile Atlantic salmon (Salmo salar) are, in general, well known, but vary in quality, related to interacting effects of several variables, which may depend on different parts of a river system. Examples are given of ranges of densities and growth that can be found at various sites in eastern Canada, illustrating the biological and physico-chemical factors affecting production of juvenile salmon. Relative growth rates can indicate habitat quality and population densities. Salmon parr have negative effects on brook trout in riffle habitats. The effects of migrations within the river and of changes with stream succession on juvenile salmon production are illustrated with examples from a Newfoundland river. Migration of age-classes can be quantified from ‘self-thinning’ curves. Lakes have enhancing effects on downstream fluvial habitats, and, at least in Newfoundland, and probably in many boreal areas, the lacustrine proportion of the basin can be used as an index for deriving estimates of required spawning escapement. The factors described should be taken into account for more refined estimates of river production and management of the salmon resource.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00022.x
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  • 56
    Digitale Medien
    Digitale Medien
    Life-history variation in perch (Perca fluviatilis L.) in five neighbouring Norwegian lakes (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – We have studied the population dynamics and reproductive biology of perch (Perca fluviatilis L.) from five neighbouring lakes in Norway. The lakes vary in water quality, varying from strongly acidified (pH≤5.0) to not acidified (pH≥6.0). Estimated annual survival rates did not differ among populations. There was no strong relationship between age at maturity in female perch and acidification. However, age at maturity was lower for female perch from the most acidic lake (c. 2 years) compared with perch in the four other lakes (2.5–3.5 years). There was no relationship between acidification level and size-adjusted egg size, fecundity or reproductive investment (Gonadosomatic index – GSI). Perch in the most acidified lake showed large variation in egg size, the lowest length-specific fecundity, the highest GSI, and the lowest age at maturity. Environmental stress, such as acidification, induces a number of changes to a lake community. It is therefore difficult to predict how acidification will influence the population dynamics and reproductive biology of a perch population.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00023.x
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  • 57
    Digitale Medien
    Digitale Medien
    Seasonal and spatial variation in a prairie stream-fish assemblage (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Stream-fish assemblage and environmental data for 13 sites in the upper Brazos River, Texas, USA during 1997 and 1998 were used to assess the relationship between environmental conditions, and seasonal and spatial variation in fish species abundance and distribution patterns. There was considerable spatial variation in environmental conditions among sites. Spatial variation in species diversity and species composition was related to variation in conductance (salinity), depth and current velocity among sites and streams. Species diversity increased downstream and species composition shifted from primarily cyprinodontids upstream to cyprinids downstream. Among all dominant species, spatial components of variation in fish abundance were greater than seasonal components, suggesting that assemblage structure is determined more by average or persistent differences in environmental conditions among sites than by seasonal variation in environmental conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00005.x
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  • 58
    Digitale Medien
    Digitale Medien
    The influence of stunted body size on the reproductive ecology of bluegill Lepomis macrochirus (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Although stunting is a common phenomenon in fish populations, the consequences of stunted body size on the reproductive ecology of individuals has received little attention. The present study compares the reproductive ecology of bluegill in established stunted and non-stunted populations. Three ponds (two non-stunted and one stunted) were monitored for spawning activity throughout the summer. Parental male bluegill from both non-stunted populations were older, larger, and had greater mating success (number of eggs or fry within nests) than parental males in the stunted population. Stunted bluegill also experienced a shortened reproductive season owing to the delay in onset of spawning. The present study demonstrates that individual size and population size structure can have a marked influence on the reproductive ecology of bluegill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00011.x
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  • 59
    Digitale Medien
    Digitale Medien
    The differential effects of Ligula intestinalis (L.) plerocercoids on host growth in three natural populations of roach, Rutilus rutilus (L.) (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – This study reports the differential effect of the pseudophyllidean cestode, Ligula intestinalis, on the growth rates of three fish populations of the roach, Rutilus rutilus, under field conditions. Here, we show that only one host-population is affected by parasite-induced gigantism in the first 2 years of host life. Paradoxically, this increase in fish growth is strongly correlated with the parasitic load in plerocercoid stages, in that only the roach population subjected to the heaviest parasitic pressure shows an enhanced growth of cestode-parasitized individuals. This host gigantism observed in only one locality is associated with parasite-induced fish mortality occurring, on average, one year earlier in this fish population when compared to other populations. We discuss the different reasons for this differential parasite effect on growth enhancement across host-population in natural settings. Whether the growth effects represent an adaptive response by the host or a manipulation by L. intestinalis of the host, remains to be elucidated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00006.x
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  • 60
    Digitale Medien
    Digitale Medien
    Using allometry with fish size to estimate production to biomass (P/B) ratios of salmonid populations (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – The ratio of annual production rate to average biomass (P/B) is sometimes used as a shortcut method of estimating production if biomass is known. P/B ratios vary among salmonid populations in different areas depending on the species, fish size and growing conditions. The hypothesis that annual P/B ratios for salmonid populations can be predicted from the allometric equation: P/B = a W−0.35 was investigated in this study. The allometric coefficient (−0.35) was obtained from the literature, and W was the average weight (g) of fish in the population. Plots of P/B versus fish weight for three species of salmonids, Salvelinus fontinalis, Salmo trutta and Salmo salar, showed a declining trend, with a slope consistent with the hypothesis. The coefficient a of the allometric equation was species and habitat dependent. The efficacy of using the allometric formula to estimate the P/B ratio of specific salmonid populations is examined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00012.x
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  • 61
    Digitale Medien
    Digitale Medien
    The presence of artificial stones predicts the occurrence of the European bullhead (Cottus gobio) in a regulated lowland river in Flanders (Belgium) (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – In a regulated lowland river in Flanders (northern part of Belgium), the locally endangered bullhead was found mainly near bridges. These locations are characterised by the presence of artificial stones and a relatively high water velocity. To preserve and expand the few remaining bullhead populations, the removal of these stones should be avoided and new suitable habitats should be created.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00013.x
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  • 62
    Digitale Medien
    Digitale Medien
    Residency and movement of stream-dwelling Japanese charr, Salvelinus leucomaenis, in a central Japanese mountain stream (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – The residency and movement of stream-dwelling adult (2+ and older) Japanese charr, Salvelinus leucomaenis, were studied by mark and recapture experiments in the Jadani Stream, a headwater tributary of the Tedori River, central Japan, from 1986 to 1989. Of the marked fish, 31.3–58.3% were recaptured in the same pools where they had been caught during the study periods of summer (June–August), autumn (August–November) and winter–spring (November to the next June) and no seasonal movement was observed. The mean distances that the fish moved during the study periods ranged from 139.0 to 502.3 m and many movements longer than 1000 m were observed. Between the resident and the moved fish, there was little difference in body length, growth rate or sex. For the fish that had been resident in the same pools and riffles at previous recaptures, most fish were recaptures in the same locations at the next recapture. Conversely, for the fish that moved previously, most fish were recaptured in different locations from previous sites at the next recapture. These results suggest that Japanese charr exhibit relatively high residency throughout the year, but many fish moved longer distance. The results also suggest the presence of static and mobile components in the charr population.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00014.x
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  • 63
    Digitale Medien
    Digitale Medien
    Brown trout (Salmo trutta L.) and Arctic charr (Salvelinus alpinus (L.)) as predators on three sympatric whitefish (Coregonus lavaretus (L.)) forms in the subarctic Lake Muddusjärvi (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract  – Brown trout (Salmo trutta L.) and Arctic charr (Salvelinus alpinus (L.)) use whitefish (Coregonus lavaretus (L.)) as their main prey in the subarctic Lake Muddusjärvi. Brown trout dwelled in littoral and pelagic habitat, whereas Arctic charr lived only in epibenthic habitat. Both species shifted to whitefish predation at a length of 20–30 cm. At this size, brown trout fed on larger whitefish than Arctic charr. Whitefish occur in three sympatric forms, differing in their habitat, ecology and morphology. Both the predators preyed primarily upon the small-sized, densely rakered whitefish form (DR), which was the most numerous whitefish form in the lake. DR used both epibenthic and pelagic habitat, whereas two sparsely rakered whitefish forms dwelled (LSR and SSR) only in epibenthic habitat: LSR in littoral and SSR in profundal areas. Sparsely rakered whitefish forms had minor importance in predator diet.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.t01-2-00001.x
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  • 64
    Digitale Medien
    Digitale Medien
    Migration and life history alternatives in a high latitude species, the broad whitefish, Coregonus nasus Pallas (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – We examined the expected changes in the life history trajectory of an Arctic species, broad whitefish, in the lower Mackenzie River between an anadromous population with spawning migrations of 350–450 km and a potamodromous population with spawning migrations of 5–12 km. Based on life history theory we predicted that the anadromous population would have faster growth, later age-at-maturity, and greater reproductive investment than the potamodromous population. Early in its life the anadromous population had faster growth than the potamodromous but later growth was slower. Age-at-maturity was greater in the anadromous population than the potamodromous. Reproductive investment was higher in the anadromous population. We conclude that the broad whitefish did not conclusively follow the pattern of variation observed between migratory and relatively sedentary populations in temperate zones. Fecundity was greater in the migratory population but not conclusively linked to age-at-maturity or growth-rate differences.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00001.x
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  • 65
    Digitale Medien
    Digitale Medien
    Diet dynamics of the adult piscivorous fish community in Spirit Lake, Iowa, USA 1995–1997 (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Diets of adults of six important piscivorous fish species, black crappie Pomoxis nigromaculatus, largemouth bass Micropterus salmoides, northern pike Esox lucius, smallmouth bass Micropterus dolomieui, walleye Stizostedion vitreum, and yellow perch Perca flavescens were quantified in Spirit Lake, Iowa, USA from May to October in 1995–1997. Forty-one prey taxa were found in the diets of these species, including 19 species of fish. The most important prey taxa overall were yellow perch, amphipods and dipterans. Diets of northern pike and walleye were dominated by yellow perch. Largemouth bass diets included large percentages of both yellow perch and black bullhead Ameiurus melas. Smallmouth bass diets included large percentages of both yellow perch and crayfish. Black crappie and yellow perch diets were dominated by invertebrates, primarily amphipods and dipterans. There were pronounced differences in diets among species, among size classes within species and over time. Most of the dominant prey taxa we documented in the diets of piscivorous species were in accordance with previous studies, but a few deviated significantly from expectations. Many of the temporal diet changes were asynchronous among piscivorous species and size classes, suggesting different responses to common prey resources over time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00015.x
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  • 66
    Digitale Medien
    Digitale Medien
    Size-related habitat use by bitterling (Rhodeus sericeus) in a regulated lowland river (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract  – Habitat use by four size-classes of bitterling (Rhodeus sericeus) in a regulated lowland river was studied at two spatial scales. Mesohabitat scale was represented by the bank type (boulder, beach and steep eroded bank). Microhabitat associations with substrate types, vegetation, woody debris and position in the stream were examined at each mesohabitat scale. Three size cohorts of young-of-the-year (0+) fish and a group of adult bitterling were detected. Univariate (χ2-tests) and multivariate (Outlying Mean Index analysis) methods were applied to determine size-related habitat associations. All the size-classes of bitterling avoided the steep eroded bank and most 0+ bitterling were distributed along the boulder bank. The smallest fish had the most pronounced habitat requirements and occurred mostly in the depositional areas, whereas the larger 0+ fish occurred in deeper water. The size-related change in the habitat use coincided with a change in diet and morphological state.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00002.x
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  • 67
    Digitale Medien
    Digitale Medien
    Influence of site characteristics on fish community patterns in French reservoirs (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – The objectives of this paper are to describe the fish assemblages in French reservoirs and to relate them to the sites' characteristics. The results of 43 fishing surveys were collected and completed with environmental descriptors. Fish assemblages differ between salmonids-dominated mountain sites and lowland ones. The latter show higher species diversity and a distinction between rheophilic- and limnophilic-type communities. This distinction can be explained by the reservoir age, location in the catchment and depth. The response of fish communities to these variables was investigated by canonical correspondence analysis. It shows that rheophilic species are typically abundant in upper basin, deep and recently created reservoirs. The fish community response to the aging process corresponds to an addition of lowland standing waters species and an extinction of the native riverine ones. The structuring role of the sites' depth, location and age is discussed, considering their relationship with the water body trophic status.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00004.x
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  • 68
    Digitale Medien
    Digitale Medien
    Habitat use and foraging success of 0+ pike (Esox lucius L.) in experimental ponds related to prey fish, water transparency and light intensity (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract  – This study investigated the habitat use of 0+ pike (9–17 cm) in relation to two different water transparency regimes (clear water/chlorophyll water), two different light regimes (day/night) and the presence/absence of prey using 16 m2 experimental ponds. Pike could freely choose between two structured habitats (a simple structured and a complex structured), an interface habitat (between the structured habitats and open water) and an open water habitat. Foraging success of the pike in relation to water transparency was investigated by comparing mean condition (Fultons K) of the pike as well as the number of surviving prey fish. Habitat use was influenced by the presence/absence of prey and varied between waters with different transparency. The presence of prey intensified the use of structural habitats of 0+ pike in both clear and chlorophyll waters. A preference for complex habitats was found in clear water and was presumably related to foraging. The pike in chlorophyll water, in contrast, appeared more evenly distributed among all habitats, as illustrated by a more intensive use of open water in chlorophyll water compared to the clear water. No detectable impact of water transparency on the foraging success of 0+ pike was found.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00008.x
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  • 69
    Digitale Medien
    Digitale Medien
    Microsatellite diversity assessment of brown trout (Salmo trutta) population structure indicate limited genetic impact of stocking in a Norwegian alpine lake (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Releases of non-native trout often result in introgression into natural populations and negative genetic effects. The causal ecological mechanisms for a wide range of reported outcomes are poorly understood. Brown trout population structure in an alpine lake with three major recruitment streams was assessed by analysis for eight DNA microsatellite markers and compared with the non-native population. The lake is subject to a 40-year recorded history of stocking with exogenous trout. No certain deviations from Hardy–Weinberg equilibrium were found. Tests for population differentiation and genetic distance indicated separate populations for all the sampled areas, and with the exogenous population as a cluster quite different from the others. Assignment tests indicated that only a small fraction of the fish sampled from the lake originated from the introduced trout strain (〈3%). Wild discriminate, naturally reproducing populations characterize this alpine lake ecosystem, in spite of 40 years of stocking, which appears to have had a limited impact. It is unlikely that this population structure can ultimately be explained by trout movement patterns. Genetic analysis needs to be supplemented by studies of local life history strategies, to evaluate the relative importance of local adaptation versus random genetic differentiation, because implications for conservation and management are different.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.00009.x
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  • 70
    Digitale Medien
    Digitale Medien
    Recruitment patterns of six species of cyprinid fishes in the lower River Trent, England (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Fisheries data were collected for six species of 0-group cyprinid fishes from eight sites in the lower reaches of the River Trent, England, between May and October 1999 inclusive, using a micromesh seine net. Recruitment and growth patterns were observed via monthly length–frequency histograms and estimations of mean length. In the cases of roach and dace, growth was approximately linear through the summer, before declining in September and October. In the cases of chub and gudgeon, and to a lesser extent bream and bleak, however, there were suggestions of multiple recruitment events. It is argued that some of the fish species examined in the present study adopt fractional or protracted spawning strategies in the lower River Trent.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.t01-1-00001.x
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  • 71
    Digitale Medien
    Digitale Medien
    Assessment of movements of resident stream brown trout, Salmo trutta L., among contiguous sections of stream (2002)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – The present authors studied the movements of resident stream brown trout, Salmo trutta L., in Valley Creek, Chester County, Pennsylvania, USA, using mark-recapture techniques as well as radio telemetry. The novel characteristic of this study is that the entire stream was sampled during recapture, thus minimizing the possibility of bias during this portion of the analysis. The authors tagged 627 trout between June and September, 1995, and made 94.6% of recaptures in December, 1995, and 98.5% of recaptures in March, 1996, within 800 m of the initial tagging sites. They also implanted six trout with radio transmitters and made 94.6% of contacts within 800 m of the initial implantation sites. The data, which were pooled from mark-recapture and radio telemetry studies, show that 95.5% of all recaptures and contacts were within 800 m of initial tagging sites. These results, derived from complete stream sampling, support previous studies indicating that a high percentage of resident stream salmonids remain in the same area of stream throughout the year./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.110203.x
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  • 72
    Digitale Medien
    Digitale Medien
    Feeding ecology and habitat of the threespine stickleback, Gasterosteus aculeatus microcephalus, in a remnant population of northwestern Baja California, México (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – The feeding ecology and habitat of the threespine stickleback (Gasterosteus aculeatus microcephalus Girard, 1854) was studied from November 1996 to May 1997 in a remnant population of northwestern Baja California, México. The analysis of the stomach content of 179 individuals (25 to 56 mm standard length [SL]) showed a diet dominated by cyclopoid copepods (43.8%) and chironomid larvae (39.1%). Diet in relation to size and sex of the fish was dominated by copepods in autumn and winter and by chironomid larvae during spring. Diet overlap (Schoener’s index) was significant (≥60%) between fish size-classes in January, March and April and between sexes for most sampling months. The average size of prey consumed was independent of fish mouth size. The feeding strategy of the threespine stickleback shifted from opportunist in winter to specialist in spring./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100401.x
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  • 73
    Digitale Medien
    Digitale Medien
    Diet dynamics of the juvenile piscivorous fish community in Spirit Lake, Iowa, USA, 1997–1998 (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – We assessed temporal dynamics and variation among species and age-classes in the diets of age 0 and age 1 piscivorous fish species in Spirit Lake, Iowa, USA during 1997 and 1998. Species included walleye Stizostedion vitreum, yellow perch Perca flavescens, smallmouth bass Micropterus dolomieui, largemouth bass Micropterus salmoides, black crappie Pomoxis nigromaculatus and white bass Morone chrysops. Thirty taxa were identified in diets, including 12 species of fish. We found dramatic differences in diets among species, among age-classes within species and over time. Walleye, largemouth bass, smallmouth bass and white bass were piscivorous at age 0. Black crappie began piscivory at age 1. Yellow perch also began piscivory at age 1, but fish were a very small fraction of age-1 diets. The primary temporal pattern, seen in several species and age-classes, was an increase in piscivory from spring to fall. This pattern was due to the lack of small, age-0 prey fish in spring. Although some patterns were evident, the taxonomic composition of the diets of all species was highly variable over time, making generalizations difficult. A surprising result was the absence of yellow perch in the diet of age-0 walleye, despite their abundance in Spirit Lake and prominence in diets of age-1 walleye and other age 1-piscivores. Age-0 yellow perch were consistently too large to be eaten by age-0 piscivores, which preyed primarily on invertebrates and smaller fish such as johnny darters Etheostoma nigrum and age 0 bluegill Lepomis macrochirus. This finding suggests that predator-prey interactions and resulting population dynamics may be quite different in Spirit Lake than in other systems dominated by walleye and yellow perch./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100402.x
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  • 74
    Digitale Medien
    Digitale Medien
    Denil fishway utilization patterns and passage of several warmwater species relative to seasonal, thermal and hydraulic dynamics (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Two different Denil fishways on the Grand River, Ontario, were used as check-points to evaluate the upstream movement of fishes past a low-head weir and to examine the proportions and inferred swimming performance of non-salmonid warmwater fishes that used each fishway type. Traps installed at fishway exits were used to collect fish during 24-hour sampling periods, over 40–51 days each year, from 1995 to 1997. Passage rates, size selectivity, water temperature, water velocity and turbidity for the periods of maximum passage for each year were examined. General species composition from trap samples shifted from catostomids to cyprinids to ictalurids to percids and centrarchids, with some overlap, as water temperatures increased from 8 °C to 25 °C in the spring and early summer. Water depths, and therefore water velocities in each fishway, were independent of river discharge due to variable accumulations of debris on upstream trash-racks. Relationships between the water velocity and the swimming and position-holding abilities of several species emerged. Turbidity was directly related to river discharge and precipitation events, and many species demonstrated maximum fishway use during periods of increased turbidity. This study 1) provided evidence of strongly directional upstream movements among several species that were previously considered non-migratory and 2) describes physical and hydraulic conditions during fishway use for 29 non-salmonid fish species./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100403.x
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  • 75
    Digitale Medien
    Digitale Medien
    Effects of environmental factors on size-related growth efficiency of perch, Perca fluviatilis (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Two aspects of size-dependent growth were addressed using perch, Perca fluviatilis L, from 22 Swedish lakes. Firstly, maximum annual growth decreased linearly with length after the previous year. Secondly, median or realized growth showed a non-linear pattern, with minimum growth efficiency at intermediate length, probably related to the shift from invertebrate to fish diet. Between-lake variation in size-related growth efficiency was better explained by fish community characteristics than by abiotic factors. The growth of most size classes was negatively related to fish biomass, especially to biomass of 100 to 199-mm perch. Growth efficiency of perch 〉200 mm was positively related to the proportion of large perch in the community. These size- and density-dependent growth responses suggest that effects of competitive and predatory interactions will often mask the controlling or limiting effects of abiotic factors, such that realized growth of individuals and populations are poorly described by deterministic asymptotic growth models./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100407.x
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  • 76
    Digitale Medien
    Digitale Medien
    Is scuba sampling a relevant method to study fish microhabitat in lakes? Examples and comparisons for three European species (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – We compared fish microhabitat use patterns in the littoral zone of a lake using a new direct method (point abundance sampling by scuba, PASS) and the widely used point abundance sampling by electrofishing technique (PASE). We collected microhabitat data for age 0+ roach (Rutilus rutilus L.), perch (Perca fluviatilis L.), and pike (Esox lucius L.). The two methods yielded different results for fish assemblage structure and microhabitat patterns. Using PASE, fish were mainly found in “shelter habitats” such as shallow waters and dense vegetation. It is likely that this behavior is caused by the disturbance of the observer stamping around. Using PASS, fish escapement behavior was rarely observed. Therefore, we concluded that this direct and nondestructive sampling technique can be used to provide an accurate microhabitat estimation of a fish community and is assumed to be more suitable than PASE for fish habitat studies./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100303.x
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  • 77
    Digitale Medien
    Digitale Medien
    Production and predation rates in a cannibalistic Arctic char (Salvelinus alpinus L.) population (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Production of cannibalistic Arctic char (Salvelinus alpinus (L.)) and their prey conspecifics were estimated in an allopatric population, situated in an alpine ultraoligotrophic lake in central Norway. Estimates of population abundance were obtained by mark recapture and successive removal experiments. Assuming stable age distribution, we estimated mean yearly biomass (±95% CL) of char in sampled size groups vulnerable to predation (60 to 150 mm) to 7.93 (5.11–14.30) kg · ha−1. Similarly, mean yearly biomass (±95% CL) of cannibalistic char (〉 250 mm) was estimated to 0.62 (0.50–1.06) kg · ha−1. Annual production (±95% CL) of char in length groups 60 to 150 mm was estimated to be 4.31 (2.74–8.03) kg · ha−1 · year−1, and production (±95% CL) of cannibalistic char to 0.19 (0.15–0.33) kg · ha−1 · year−1. Depending on the food conversion factor (set to vary from 0.1 to 0.4), the cannibalistic char removed from 10% to 40% of the production of char in sampled size-classes vulnerable to predation yearly. The overall ecological efficiency in energy transfer between the prey and predator population was 4.4%./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100404.x
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  • 78
    Digitale Medien
    Digitale Medien
    Physical activity and behavior of a centrarchid fish, Micropterus salmoides (Lacépède), during spawning (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – The spawning behavior of male and female largemouth bass Micropterus salmoides (Lacépède) was studied in central Illinois during the spring of 1998 to examine patterns of muscular activity associated with different spawning related behaviors and to evaluate whether electromyogram (EMGi) telemetry could be used to detect spawning activity. Fish were implanted with EMGi transmitters (8 females, 16 males) on April 7, prior to the initiation of spawning, and were released in four 0.10-ha earthen research ponds. Continuous EMGi records, underwater videography and additional visual observations for one pair of EMGi tagged fish were collected throughout the entire spawning event, allowing us to quantify behavioral correlates of physical activity. Male EMGi activity patterns were only correlated with female patterns during courting and periods of male aggression toward the female. Overall, EMGi activity was highest for the female during shuddering (gamete deposition), whereas male EMGi activity was similarly high during periods of nest excavation, shuddering and post-spawn parental care activities. During spawning, female EMGi activity was positively correlated to shuddering. Average daily EMGi activities for females peaked on the day of spawning. As a result of their engagement in parental care activities, male activity continued to rise even after spawning was completed. EMGi telemetry appears to be a useful technique for monitoring the reproductive activity of largemouth bass, especially in areas of high cover or turbid water or during low light conditions. This technology permitted us to quantify and contrast the activity patterns associated with different spawning related activities, information that will be required to construct accurate, gender-specific bioenergetics models for this species./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100405.x
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  • 79
    Digitale Medien
    Digitale Medien
    Movements and habitat utilization of three cichlid species in the Zambezi River, Namibia (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – During 5–7 October 1999, 16 cichlids (30.5–51.0 cm) were tagged with radio transmitters in the Zambezi River in Namibia (eight threespot tilapia Oreochromis andersonii, seven pink happy Sargochromis giardi and one humpback largemouth Serranochromis altus). The main objectives of this pilot study were 1) to assess whether and how telemetry can be used to follow the movements of larger cichlids in the upper Zambezi River and 2) to study the movements, habitat preferences and homing behavior of three cichlid species important for subsistence and trophy fishing during a period of increasing water flow towards the rainy period. Nine fish showed a downriver movement immediately after release, believed to be a behavioral response to catch and tagging. From 11 October, only small-scale movements were recorded. Average total distance moved from 11 October to 1 March was 375 m (range=1–1150) for threespot tilapia and 1276 m (range=540–1990) for pink happy. The farthest position compared to the position held on 11 October was on average 220 m away (range=0–500) for threespot tilapia and 538 m (range=20–1500) for pink happy. Displaced individuals did not show homing to the catch site. The threespot tilapia were, on average, located in the main river during 67% of the tracking surveys, in backwaters during 13% and in mouth of backwaters during 20%. The pink happy were, on average, located in the main river during 71% of the tracking surveys, in backwaters during 25% and in mouth of backwaters during 4%./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100406.x
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  • 80
    Digitale Medien
    Digitale Medien
    Ontogeny and dietary specialization in brown trout (Salmo trutta L.) from Loch Ness, Scotland, examined using stable isotopes of carbon and nitrogen (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – The trophic ecology of many fish species in cold temperate lakes is often characterized by a generalist or opportunist strategy. In this study, the diets of polytrophic brown trout in Loch Ness, Scotland, have been examined using stable isotopes of carbon and nitrogen to complement gut content analyses and aging by otolith annuli counts. Using the stable isotope ratios, it was possible to trace trout ontogeny from parr development in a natal river to piscivory in the pelagic. Potential dilution of maternal isotope signatures from eggs to parr was also demonstrated. Despite the low productivity of the loch, intraspecific variability in isotope ratios suggested dietary specialization, rather than opportunism, in some individuals./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100306.x
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  • 81
    Digitale Medien
    Digitale Medien
    Temporal food web variability in an upper Missouri River backwater: energy origination points and transfer mechanisms (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Energy transfer mechanisms often cannot be identified with either an isotope or a food habits analysis; however, a combined assessment provided collaborative support for depicting backwater food webs. Lateral dimensions in riverine function substantially influence backwater ecology; however, backwater communities are highly dynamic and infrequently investigated due to logistical difficulties. We created seasonal food webs for an upper Missouri River backwater using a combined food habits and stable isotope analysis. Temporal transition of energy origins was apparent. In the spring, carbon primarily originated from sediments, detritus and periphyton. During mid-summer, carbon was derived from a variety of sources, but included large proportions of terrestrial plants and particulate organic matter. By early fall, the backwater was uncoupled from the river, and autochthonous phytoplankton appeared to be the dominant carbon source. During all sample periods, Chironomidae was an important trophic link conveying energy from the primary producers to the higher consumers. Additionally, zooplankton were an important energy transfer taxa to the abundant age-0 fish community in the fall, and Corixidae were important in the spring./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100305.x
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  • 82
    Digitale Medien
    Digitale Medien
    Estuarine predation on radiotagged wild and domesticated sea trout (Salmo trutta L.) smolts (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Avian predation on emigrating wild and domesticated sea trout smolts was investigated in a fjord in the western Baltic Sea. In April 1997, 50 domesticated and 50 wild smolts were intraperitoneally tagged with radio-transmitters and released in a small coastal stream. Predation was recorded by signal interception in an estuarine breeding colony of cormorants and herons near the outlet of the stream. Of the 78 emigrating smolts, 51 (65%) were recorded as eaten. Predation rates were significantly higher among small than large smolts and significantly higher among domesticated smolts. The first 2 days after entering the sea, both wild and domesticated smolts suffered a severe daily predation rate (range 20–34%). The results support the hypothesis of a transient period immediately after exposure to full-strength sea water, where smolts experience an elevated risk of predation. A transient increase in postsmolt mortality may be found also in moderately saline environments (20–23 ppt)./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100307.x
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  • 83
    Digitale Medien
    Digitale Medien
    Reproductive characteristics of female longnose dace in the Coweeta Creek drainage, North Carolina, USA (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – We examined the reproductive characteristics of 38 female longnose dace (Rhinichthys cataractae) from one of the southernmost populations of this species during two sampling periods in 1999 (ES=March 1999, LS=June 1999). Our data indicated that ES fish had not spawned, whereas LS fish had begun spawning. The smallest mature female captured was 56 mm SL (age 1+). Mean potential fecundity differed significantly between ES (mean±1 SD=1832±572 oocytes) and LS (mean±1 SD=775±415 oocytes) specimens. Potential fecundity was positively correlated with both standard length and somatic mass for both ES and LS specimens. Oocyte diameter frequency histograms indicated that ES specimens possessed two modes of oocytes, whereas LS fish contained two or three modes. Female longnose dace appeared to spawn more than once during a reproductive season. Oocyte number varied substantially both among individuals within periods and between periods. The number of Mode II oocytes in ES fish was positively correlated with both length and somatic mass. Female longnose dace appeared potentially capable of spawning 6+ clutches per year. GSI values for longnose dace ranged from a high of 21.4% (LS specimen) to 2.4% (ES specimen). Regression analysis demonstrated that there was no evidence of differential reproductive effort between longnose dace of different size in this population./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100308.x
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  • 84
    Digitale Medien
    Digitale Medien
    Long-term dynamics of pelagic fish density and vendace (Coregonus albula (L.)) stocks in four zones of a lake differing in trawling intensity (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – An 11-year time series of hydroacoustic fish density estimates and fisheries statistics of vendace (Coregonus albula (L.)) from four zones of a lake differing in trawling intensity was analyzed in order to test the hypothesis that intensive trawling has detrimental effects on pelagic fish stocks, especially vendace recruitment. The standardized fish density estimate in trawled zones showed no decrease in comparison to the non-trawled zone. No signs of recruitment failure associable with trawling intensity were found. The growth of vendace at the end of the study period was slower than that at the beginning, indicating a higher density, most clearly so in the zone with highest trawling intensity. No significant correlations were detected between 3-year mean trawling intensity and yield per unit effort of over-1-year-old vendace or fish density in any zone. Thus, no evidence to support the hypothesis was found. This was suggested to be due to density-dependent compensatory processes in recruitment and/or natural mortality effectively counteracting the population change induced by exploitation./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100201.x
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  • 85
    Digitale Medien
    Digitale Medien
    Reproduction in three species of rainbowfish (Melanotaeniidae) from rainforest streams in northern Queensland, Australia (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – The reproductive biology of three species of rainbowfish (Melanotaeniidae) in northeastern Australian rainforest streams was investigated. Two species, Melanotaenia eachamensis and Cairnsichthys rhombosomoides are endemic to the area, whereas the third, M. splendida splendida, is more widespread. The species were all highly fecund, producing many hundreds of eggs between 1.10 and 1.24 mm in diameter. Melanotaenia eachamensis was the most fecund, produced the largest eggs of the three species, and consequently exhibited the greatest maternal investment (as measured by gonadosomatic index). The majority of reproductive effort occurred during the dry season, although reproductively active fish were present year-round for each of the species, but particularly so for M. s. splendida and C. rhombosomoides. No evidence for a role by temperature or photoperiod as environmental cues for reproduction was found, and it was suggested that gonad development was strongly tied to somatic growth. The concentration of reproduction to the dry season ensures that larvae are produced during a period of relatively stable and benign physical conditions. Comparison of temporal changes in gonadosomatic index values suggest that the spawning season of M. eachamensis, which occurs in high-elevation streams, is more restricted and commences about 1 month earlier than either other species. A similar phenology was observed for the M. s. splendida population found at high elevation and highlights the potential for spatial differences in stream productivity to influence life history./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100202.x
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  • 86
    Digitale Medien
    Digitale Medien
    Growth and mortality of prairie stream fishes: relations with fish community and instream habitat characteristics (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Few studies have been conducted to describe the age structure, growth rates and mortality of fishes in small stream ecosystems. The purpose of this study was therefore to determine age structure, growth rates and mortality (i.e., total annual mortality and, age-specific mortality) of central stonerollers Campostoma anomalum, creek chubs Semotilus atromaculatus, red shiners Cyprinella lutrensis and green sunfish Lepomis cyanellus from 13 streams on Fort Riley Military Reservation, Kansas, using incremental growth analysis. Further, we were interested in determining the influence of fish community and instream habitat characteristics on growth rates. The age structure of central stonerollers, creek chubs, and red shiners was dominated by young individuals (i.e., less than age 2); however, over 60% of the green sunfish were age 2 to age 4. Mean total annual mortality was 〉60% for cyprinids and averaged approximately 44% for green sunfish. The age-specific mortality of central stonerollers and red shiners was generally less than 45% between age 0 and 1 and increased to over 85% for fishes greater than age 1. Fish community characteristics (e.g., catch per unit effort of trophic guilds) and chemical habitat (e.g., total phosphorous) were not related to growth rates (P〉0.05). Growth of central stonerollers was not significantly correlated with physical habitat (P〉0.05). However, the growth increments of creek chubs, red shiners, and green sunfish were related to the amount of woody debris (e.g., total woody debris, log complex habitat; r〉0.60; P≤0.05). The results of this study provide important information on the population dynamic rate functions of cyprinid and green sunfish populations in small prairie streams. Furthermore, these data suggest that woody debris is important habitat influencing growth of stream fishes./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100203.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 87
    Digitale Medien
    Digitale Medien
    Piscivory in larval perch (Perca fluviatilis): mechanisms structuring larval roach (Rutilus rutilus) cohorts (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Perch (Perca fluviatilis) can act as a piscivore from larval stage VI (body size 10.3 mm) on newly hatched larval roach (Rutilus rutilus), bream (Abramis brama) and smaller siblings of its own cohort. Consumption rates at this stage were approx. 0.5 prey/perch*h at 21°C. Larval perch predation was strongly gap-limited, and the maximum size of roach consumed by perch (perch length interval 10.3–62.0 mm) under experimental conditions followed the linear regression, Pprey-max.=0.478*LPred.+1.829 (r2=0.99, P〈0.001, n=12). Under experimental conditions, predatory 0+ perch substantially affected the size distributions of 0+ roach prey cohorts, since smaller prey individuals were predated more frequently than larger ones. In both unimodal and bimodal size distributions of prey roach, the distributions changed according to the maximum prey size consumed by the added predatory perch. Unimodal prey distributions were positively skewed when piscivorous perch were added compared with controls without predators. According to the size distributions of lake-living 0+ roach and 0+ perch and the relative size difference between prey and predator, the vulnerability of 0+ roach cohort to 0+ perch predation changed from June to September. Prey vulnerability was extremely sensitive to the relative size difference between predator and prey. Therefore differences in hatching time and growth rates between the two species will strongly influence the potential for predator-prey interactions./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100204.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 88
    Digitale Medien
    Digitale Medien
    Nest site selection and aspects of the reproductive biology of the pygmy sculpin (Cottus paulus) in Coldwater Spring, Calhoun County, Alabama (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Imperiled pygmy sculpins are known from only one locality in Alabama, USA. One conservation strategy for the species is the creation of another population by introducing the species into a suitable habitat. Before such action is considered, however, an understanding of the life history, including reproductive biology and habitat use, of the species must be obtained. In this study, nesting of pygmy sculpins was found to peak in July, although the species has an extended reproductive period. Preferred nesting sites had higher flow and shallower water depth than the surrounding habitat. Pygmy sculpins readily used artificial nest substrates that were introduced into the spring run, where natural nest substrate was uncommon./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100207.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 89
    Digitale Medien
    Digitale Medien
    Parasitism, water temperature and life history characteristics of the freshwater fish Gobiomorphus breviceps Stokell (Eleotridae) (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Life history traits can vary among populations of the same fish species in response to selective pressures exerted by the local environment. Here we used inter-population comparisons to investigate the effects of parasitism and variability in water temperature on life history traits in a New Zealand freshwater fish, the upland bully. Although age and size at maturity varied among populations, they were not significantly related to either temperature regime or average parasite load. Trade-offs between egg size and clutch size were only apparent in one of the seven populations when populations were analyzed separately but became clear when all data were pooled. However, neither average population clutch size or egg size was related to the population’s mean parasite load or the local temperature regime. Although the latter two parameters may influence other life history variables, such as the number of clutches produced per season and the partitioning of eggs among clutches, there was no evidence that they influenced life history strategies of the upland bully populations investigated here./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100205.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 90
    Digitale Medien
    Digitale Medien
    Energy reserves and reproductive investment in male three-spined sticklebacks, Gasterosteus aculeatus (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – In a 6-month study of male sticklebacks from a single cohort of an annual population, energy reserves (carbohydrate, lipid and protein) in the carcass and gonad were found to increase from December to May. Energy reserves in the liver increased from December to March before declining between March and April, a period of marked gonadal growth in this population. Examination at the individual level of the interrelationships among the various components of the energy store (corrected for differences in body size) identified overall body condition as a major component of variation and highlighted a negative relationship between energetic investment in gonadal tissue and energy reserves in various somatic compartments. Early in the season, relative gonadal weight was largely unrelated to somatic energy reserves, but from March onwards there was a negative correlation between these two variables. These data suggest that a significant flux of glycogen and lipid from the somatic to the gonadal tissue occurs in male sticklebacks in the period just prior to the breeding season, with the extent of gonadal growth varying between individuals and occurring at the expense of overall nutritional status./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100206.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 91
    Digitale Medien
    Digitale Medien
    Validation of the otoliths for age determination in Barbus sclateri (Günth.) (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Otoliths were used to explore the timing of annulus formation in Barbus sclateri. Lapillus exhibited opaque and translucent zones whose combination was formed once a year. Opaque zones appeared formed from July and January, and the translucent ones from February to June. We describe a procedure to assess age by using the number of annulii, the condition of the otolith’s edge and the capture date. The use of otoliths for age determination in this cyprinid endemic to the Iberian Peninsula provides a useful alternative to the traditional methods of scale reading./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100208.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 92
    Digitale Medien
    Digitale Medien
    Does timing of daily feeding affect growth rates of juvenile three-spined sticklebacks, Gasterosteus aculeatus L? (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – To assess the consequences of unpredictability in the availability of food, this study measured the effect of timing of the daily feeding on food consumption and growth rates of juvenile Gasterosteus aculeatus. The experiment lasted 21 days at 14 °C and a photoperiod of 10 hours of light and 14 hours of dark. Fish were housed individually and allocated at random to three treatments. The mean initial weight of fish was 0.402 g. Group 1 were fed live enchytraeid worms for 2 h after lights came on (“morning”), group 2 was offered food for 2 h randomly at any time of the day (“random”) during the light period and group 3 received food for 2 h before the lights went off (“evening”). There was no significant effect of timing of feeding on mean daily food consumption, which was 0.052 g day−1. Daily consumption on the random schedule was more irregular than on the two fixed schedules. Timing of feeding had no significant effect on mean specific growth rate (G) (2.42% day−1), gross growth efficiency (23.3%), white muscle RNA:DNA ratio (5.6), carcase lipid content (31.7% dry wt) and carcase dry matter content (27.4% wet wt). Thus, a lack of predictability in the availability of food during the light period of the day did not impose a detectable cost on the growth performance of the stickleback./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100301.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 93
    Digitale Medien
    Digitale Medien
    Genetic structure of New Zealand eels Anguilla dieffenbachii and A. australis with allozyme markers (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Glass eels and adults of Anguilla australis and A. dieffenbachii were collected from rivers in the North and South Islands of New Zealand and tested for nine and ten allozyme loci, respectively. There was no heterogeneity among glass eel samples, but there was heterogeneity among adult samples within species. The results indicate that there may be single panmictic populations subject to sweepstake events or different selective pressures in the adult environments./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100302.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
    Digitale Medien
    Digitale Medien
    Spatiotemporal variation in the distribution of eel (Anguilla spp.) populations in three New Zealand lowland streams (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Populations of shortfinned eel (Anguilla australis) and longfinned eel (A. dieffenbachii) were sampled at randomly chosen sites along the length of three New Zealand streams during summer for three consecutive years to determine their variability in size distribution between streams, reaches (within streams) and years. The longfinned eel was numerically dominant in two of the streams, whereas the shortfinned eel was more abundant in the third stream. For comparisons, the data were stratified into 100-mm size classes for eels ≤600 mm long, whereas eels 〉600 mm were pooled into a single class. Log-linear analysis indicated that the size distribution of both species differed significantly between streams. Moreover, the size distribution of shortfinned, but not longfinned eels, differed significantly between reaches. Neither species showed significant change in size distribution between years. In contrast to the shortfinned eel, the density of longfinned eel ≤100 mm long was consistently low for all three years, which probably indicates poor recruitment./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100304.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    Digitale Medien
    Digitale Medien
    Life-history of the flagfin shiner, Pteronotropis signipinnis, from a blackwater stream in southeastern Mississippi (2000)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 9 (2000), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Flagfin shiners, Pteronotropis signipinnis, were collected from Sweetwater Creek, a second-order blackwater stream in southeastern Mississippi, during each month of 1996. Analysis of length frequency histograms indicated a life span of 1 to 2 years. Sex ratio was not different from a 1:1 ratio. Adult males were larger and more heavily pigmented near the abdomen than females. Females were reproductive from April to mid-August. All females attained sexual maturity by 27 mm SL and produced multiple clutches of ova. Clutch size varied from 12 to 101 ova and was correlated with SL. Mean mature oocyte diameter was 0.88 mm (range 0.76–0.96). Despite the relationship between clutch size and body size, P. signipinnis may be selected to invest in early reproduction rather than growth. This idea is supported by the small size at maturity in this species and is consistent with an opportunistic life-history strategy./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2000.eff090404.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    Digitale Medien
    Digitale Medien
    Resource partitioning between lake-dwelling Atlantic salmon (Salmo salar L.) parr, brown trout (Salmo trutta L.) and Arctic charr (Salvelinus alpinus (L.)) (2000)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 9 (2000), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Resource partitioning between Atlantic salmon parr, brown trout and Arctic charr was studied throughout the ice-free season in a north Norwegian lake. Juvenile salmon and trout (≤160 mm) utilized the littoral zone and juvenile charr the profundal, while adult trout and charr (〉160 mm) were found in both. Juvenile salmon and trout had a similar diet, although trichopteran larvae were more important for the trout and chironomid pupae and three-spined sticklebacks for the salmon parr. Small salmon and trout parr (≤120 mm) had a higher diet overlap than larger parr (121–160 mm). The feeding habits of adult trout were similar to that of juvenile trout, but the former took larger prey items. At the population level, both salmon and trout were generalistic feeders with a broad diet, but at the individual level, both species had specialized on a single or a few prey categories. Juvenile charr were segregated from salmon and trout in both habitat and food utilization; they had a narrow diet consisting of chironomids and zooplankton, possibly reflecting their confinement to the profundal habitat which have a low diversity of potential prey. Larger charr also took zoobenthos and sticklebacks in the littoral zone./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2000.eff090402.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Digitale Medien
    Digitale Medien
    Stream habitat use and diet of juvenile (0+) brown trout and grayling in sympatry (2000)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 9 (2000), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – Electrofishing survey data and experiments carried out in a semi-natural stream were used to test the hypothesis that interactions between underyearling (0+) trout and grayling during their first summer affect habitat use and diet. The survey data revealed a general difference in habitat use, with 0+ grayling being more common than 0+ trout in large streams and deeper sections. It was also found that in the presence of trout, finer substrate and shallower sections were utilised more by grayling. Field experiments were carried out with three treatments; trout alone, grayling alone and the two species together. In both the July and September experiments grayling tended to occupy deeper sections than trout. Trout abundance was higher in shallow areas in sympatry, while no such difference was found in allopatry. The rate of disappearance of grayling from the study sections was significantly higher in sympatry in July, while no difference was found in September. In July the size difference between species and the degree of dietary overlap were small and non-significant, respectively, indicating that the two species were strongly competing./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2000.eff090401.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    Size-related differences in diel activity of two species of juvenile eel (Anguilla) in a laboratory stream (2000)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 9 (2000), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – The diel activity of three size groups (small=〈100 mm; medium=100–199 mm; large=200–299 mm total length) of juvenile shortfinned (“shortfin”) eels (Anguilla australis) and longfinned (“longfin”) eels (A. dieffenbachii) was tested in a laboratory flow tank over a 48-h period during summer. All size groups of both species were nocturnally active, with the eels hiding in the substratum during the day and coming out on top of the cobbles from dusk to dawn, to feed. During the foraging period, the numbers and activity of all sizes of longfins visible were greater than those seen of shortfins, with the differences being more pronounced for small and medium eels. The activity of all eels consisted mostly of foraging by crawling, searching and probing for prey among the cobbles. Rate of activity increased with size of eel for both species. Small eels of either species did more swimming than eels of the larger sizes, whereas large eels were observed more frequently with only their head out of the substrate than were the smaller individuals. Feeding of small eels within the interstitial spaces of the streambed may explain their significantly lower activity on top of the substrate at night. The significantly lower rate of activity recorded for shortfins than longfins of all sizes may be due partly to their ability to feed within the interstices of the stream bed, and (or) longer time to recover from handling and habituate to the test environment./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2000.eff090403.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    Acknowledgements to reviewers (2000)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 9 (2000), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2000.eff090408.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Diel distribution of age-0 largemouth bass, Micropterus salmoides, in B. E. Jordan Lake, North Carolina (USA) and its relation to cover (2000)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 9 (2000), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract – We used prepositioned area electrofishers (PAEs, 10×1.5 m) to assess diel differences in distribution of age-0 largemouth bass, Micropterus salmoides, in August 1992–1993 in a paired sampling design. PAEs were placed parallel to shore in an embayment of an unvegetated reservoir (B. E. Jordan Lake, North Carolina, USA). The catch per unit effort (CPUE=fish/PAE) was significantly higher at night than during the day in both years, indicating that age-0 largemouth bass exhibit nocturnal inshore movements. Age-0 largemouth bass captured inshore during day were smaller than those captured at night, indicating that movement patterns may change ontogenetically. Inshore-offshore movements of age-0 largemouth bass were significantly reduced in the presence of cover, suggesting that diel movements were influenced by specific habitat components. Diel movements likely were related to foraging, resting and predator avoidance behavior and could affect population dynamics and introduce bias in assessment programs./〉
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0633.2000.eff090405.x
    Standort Signatur Erwartet Verfügbarkeit
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