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  • 1
    Electronic Resource
    Electronic Resource
    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
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0633.2004.00070.x
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  • 2
    Electronic Resource
    Electronic Resource
    Muscle development in Atlantic salmon (Salmo salar) embryos and the effect of temperature on muscle cellularity (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 44 (1994), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Salmon eggs were incubated at 5, 8 or 11° C from fertilization to hatching. At Gorodilov stages 25, 27, 29, 31 and 33 transverse sections of whole embryos (at somite level 10–15) were prepared for histochemistry and electron microscopy. At every stage up to hatching, cross–sectional areas of the embryos were not different between temperatures, and from stage 27 onwards there was also no difference in the ratio of white to red muscle. However, there were more muscle fibres but of smaller average diameter in both the red and white muscle for the colder temperature embryos. At hatching there were also more nuclei (per cross–section) in the colder embryos but more nuclei per muscle fibre in the warmer embryos. In all cases the 8° C embryos were intermediate between 5 and 11° C embryos in their muscle parameters. Fast and slow muscle fibres could only be distinguished in the embryos by alkali–stable ATPase reactions. Succinic dehydrogenase activity was low in embryonic fish. No differences between the temperature groups were detected in the histochemical reactions for either ATPase or succinic dehydrogenase activities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1994.tb01267.x
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  • 3
    Electronic Resource
    Electronic Resource
    Diel rhythm of emergence and of first displacement downstream in trout (Salmo trutta), Atlantic salmon (S. salar) and grayling (Thymallus thymallus) (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 43 (1993), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The diel rhythm of emergence from the gravel and displacement downstream has been studied in three salmonoid species: brown trout (Salmo trutta L.), Atlantic salmon (S. saiar L.) and grayling (Thymallus thymallus L.). Grayling emerged in the morning but delayed downstream displacement until the night, while the Salmo species emerged just before downstream displacement chiefly at night.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1993.tb01152.x
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  • 4
    Electronic Resource
    Electronic Resource
    Patterns of growth and smolting in autumn migrants from a Scottish population of Atlantic salmon, Salmo salar L. (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 41 (1992), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In late November 1990 salmon parr, Salmo salar L., from the Girnock Burn in northern Scotland were either caught on their feeding territories (n=25) or trapped during downstream migration (n= 18). They were then housed in a laboratory rearing tank and their food intake and growth rates were tracked, until their smolting status was ascertained in the following May. Female fish were predominant in both groups; although the range of ages was the same, the total age of migrants was 2+ while that of residents was 1+. In November, compared to resident fish of the same year class, migrants were larger, heavier and in better condition. Although growth rates dropped during the winter in both groups before increasing in spring, migrants ate more and consistently grew faster than residents. In seawater tolerance tests conducted in May, more residents than migrants failed to adapt. These results confirm the suggestion that autumn migrants smolt in the following spring and suggest that they represent the faster-growing component of their cohort.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1992.tb03867.x
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  • 5
    Electronic Resource
    Electronic Resource
    Early predictors of life-history events: the link between first feeding date, dominance and seaward migration in Atlantic salmon, Salmo salar L. (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 41 (1992), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Previous studies have suggested that the earliest fry to emerge from a salmonid redd may have an advantage in the subsequent competition for feeding sites, partly through a ‘prior residence’ effect. Here we examined whether there was any relationship between the relative date of first feeding and subsequent dominance status and growth in a sibling group of Atlantic salmon, Salmo salar L., fry. Earlier-feeding fry were dominant over their later-feeding siblings (controlling for prior residence), despite not being any larger. However, these early fish soon established and then maintained a size advantage. This led to an increased probability of early-feeding fish migrating to sea at age 1 year (rather than 2 or more). Thus a difference of less than 1 week in the relative timing of first feeding can translate into a year's difference in the timing of migration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1992.tb03871.x
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  • 6
    Electronic Resource
    Electronic Resource
    Size-related differences in behaviour and spatial distribution of juvenile Atlantic salmon in a novel environment (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 45 (1994), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Within a month of first feeding sibling juvenile salmon had developed not only large differences in size (up to fivefold in weight), but also significant differences in behaviour. Large fish remained in refuges (overhead cover) significantly longer after having been frightened. On leaving the shelters most small fish established individual territories on the bottom and. downstream of the shelters. The greater aggressiveness of small fish in a novel environment (from holding tank to experimental stream) was related to this apparent territoriality. The increased shelter residence time and delayed establishment of individual territories might be interpreted as greater caution in large fish, which are able to avoid risky situations due to their higher energy reserves. In contrast, smaller fish need to leave refuges more quickly and to establish individual territories in a novel environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1994.tb01320.x
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  • 7
    Electronic Resource
    Electronic Resource
    The movements of brown trout, Salmo trutta (L.) in Loch Leven, Kinross, Scotland (1974)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 6 (1974), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Juvenile trout enter Loch Leven during autumn and winter from the nursery streams, spend their adolescent phase offshore until reaching a length of 0.30 cm, and then move to the littoral areas in early summer. There are two types of littoral area:‘favourable‘areas from which movement of individual fish in the summer is very restricted, and‘unfavourable‘areas used briefly in early summer from which movement away is pronounced. Trout are absent from the littoral areas in winter. In subsequent summers homing to previous feeding areas is characteristic of fish from‘favourable’areas, with a tendency for older fish to move to the south east area of the loch. Spawning runs occur simultaneously into the main inflows, chiefly between October and December. Emigration into the outflow occurs, but is probably unimportant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1974.tb04534.x
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  • 8
    Electronic Resource
    Electronic Resource
    Otolith and somatic growth rates in Atlantic salmon parr, Salmo salar L: evidence against coupling (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 36 (1990), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: It is often assumed that otolith growth is in some way dependent on somatic growth (i.e. that the two processes are coupled). We examined the relationships between sagitta radius and fork length in 0+ Atlantic salmon parr that would subsequently smolt aged 1 + (UMG fish) or 2+ (LMG fish). Repeated measurements of fork lengths of individually marked parr, taken over a 211-day period from first feeding, were compared to sagitta radii on the same measuring dates (obtained by analysis of daily increments). The results showed that there was a linear relationship between fork length and otolith radius in UMG parr. However, this was not true for LMG parr. These fish enter a state of natural anorexia in their first autumn (despite excess food), but their otoliths continued to grow at the same rate despite the virtual cessation of somatic growth; they had therefore developed disproportionately large otoliths by the end of the study period. The relative growth rates of soma and otoliths first changed in LMG fish in late July/early August; this is the most precise estimate yet obtained of the timing of divergence in the developmental pathways of UMG and LMG parr. The rate of sagitta accretion was consistently lower in LMG parr, possibly indicating a lower metabolic rate in these fish. The results are discussed in relation to previous theories of the relationship between otolith and somatic growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1990.tb05599.x
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  • 9
    Electronic Resource
    Electronic Resource
    Feeding motivation and response to predation risk in Atlantic salmon parr adopting different life history strategies (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 32 (1988), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Feeding intensity was measured before (baseline level) and after (disturbed level) brief exposure to a potential predator in groups of 0+ Atlantic salmon, Salmo salar. parr destined to follow either a fast-growth, early-smolting life history (upper modal group or UMG fish) or a slow-growth, late-smolting life history (lower modal group or LMG fish). Feeding intensity decreased following exposure to the predator. While the absolute decrease in feeding intensity is constant regardless of baseline level, the proportionate decrease is negatively related to pre-presentation feeding intensity. Parr that are strongly motivated to feed thus maintain a higher food intake and incur greater risks when foraging in the presence of a predator. No differences in baseline or disturbed feeding intensity of UMG and LMG parr were found up to September of their first year. Previous work has shown that baseline feeding intensities decrease in LMG fish after September but increase in UMG fish. In the present study, these differences were reflected in greater disturbed feeding intensities in UMG fish, but fish destined to follow different life history patterns do not differ in risk-taking, once these differences in baseline feeding motivation have been taken into account.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1988.tb05416.x
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  • 10
    Electronic Resource
    Electronic Resource
    Hyperplasia and hypertrophy in the growth of skeletal muscle in juvenile Atlantic salmon, Salmo salar L. (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 37 (1990), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Both red and white muscle fibre numbers in juvenile Atlantic salmon increased gradually with fish length throughout the freshwater growth period. Mean fibre area increased as fish grew to 6.5 cm f.l., but thereafter was unrelated to fish length. Hyperplasia was most obvious when fish were growing fastest, and was the dominant growth process in fish over 6.5 cm f.l. Hypertrophy was most important when growth was slow, as in autumn and winter.Mean white fibre area was significantly smaller in deep muscle than at medial and superficial sites. Total cross-sectional area of red, white and total trunk muscle increased with fish length. The ratio of red: white cross-sectional area increased with fish length to a plateau at about 10% after 6.5 cm f.l.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1990.tb05884.x
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