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1

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Activity and food choice of piscivorous perch (Perca fluviatilis) in a eutrophic shallow lake: a radio-telemetry study (2002)

Jacobsen, Lene ; Berg, Søren ; Broberg, Mads ; [et al.]

Oxford, UK : Blackwell Science Ltd

Freshwater biology 47 (2002), S. 0

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ISSN: 1365-2427

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: SUMMARY 1. Radio transmitters were implanted in large perch (27–37 cm) in a shallow lake in Denmark. Between 6 and 13 perch were tracked every 3 h for 24-h periods twice (summer) or once a month (winter) from August 1997 to July 1998. Activity levels were recorded as minimum distance moved per hour.2. No significant differences in activity levels of individual fish were observed.3. Highest activities were observed at daytime with peaks at dawn and dusk or midday. This diel pattern was most pronounced from October to April, whereas diel variations were less in the summer months, with no peaks occurring in midsummer. The general lack of activity at night supports the idea that perch is a visually oriented forager.4. There was no significant relationship between daytime activity during the year and temperature or day length, but nighttime activity was correlated with temperature. In contrast with previous findings, activity levels varied little seasonally, except for high activity levels that occurred concomitantly with high temperatures in August. Instead, we found a significant relationship between the total distances moved per day and temperature, indicating that perch moved at the same average speed in the wintertime, but did so for shorter periods than in summer because of shorter day lengths.5. Diet of the tagged perch shifted from fish dominance between August and January to invertebrates from February to June. There was no correlation between the diet shift and activity levels, indicating that feeding on invertebrate requires similar activity levels as predation on fish.6. The results of this telemetry study throughout a year suggest that perch are more active during the winter than previously inferred from gill-net catches. This observation underscores the importance of perch as a predator of 0+ planktivorous fish in lakes and has potential implications for pelagic food web structure and lake management by biomanipulation.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2427.2002.01005.x

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Spatial and temporal distribution of fish and zooplankton in a shallow lake (2003)

Romare, Pia ; Berg, Søren ; Lauridsen, Torben ; [et al.]

Oxford, UK : Blackwell Science Ltd

Freshwater biology 48 (2003), S. 0

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ISSN: 1365-2427

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Summary 1. We performed both a large- and a small-scale echo sounding study on the spatial and temporal distribution of fish (mainly roach, Rutilus rutilus and perch, Perca fluviatlis), as well as a small-scale study of zooplankton distribution in the small, shallow and eutrophic Lake Hanebjerg in Denmark. In the small-scale study, sampling was conducted in open water as well as in the edge zone immediately outside two different types of vegetation.2. Fish daytime abundances differed between the northern and the southern parts of the lake and, on a small scale, small fish aggregated in the edge zones during day, preferably outside dense emergent vegetation. Copepods avoided emergent vegetation, while cladocerans showed no habitat preference. Both small fish and cladoceran numbers were found to be higher during night than day.3. The relative abundance (number per sample) of cladocerans in the edge zone immediately outside vegetation was negatively correlated with the relative abundance of fish in that zone. There was no correlation between cladoceran and fish abundance in open water, or between the relative abundance of copepods and fish.4. The presence of pelagic piscivores in combination with avoidance behaviour of both fish and zooplankton is a likely explanation for the observed distribution of small fish and cladocerans in Lake Hanebjerg. Both small- and large-scale distribution patterns may be dependent on the type and distribution of complex structure in the lake. Even in a small lake, large-scale patterns may affect the interpretation of small-scale data.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2427.2003.01081.x

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Pike (Esox lucius L.) stocking as a biomanipulation tool 2. Effects on lower trophic levels in Lake Lyng, Denmark (1997)

Søndergaard, Martin ; Jeppesen, Erik ; Berg, Søren

Springer

Hydrobiologia 342-343 (1997), S. 319-325

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ISSN: 1573-5117

Keywords: biomanipulation ; pike stocking ; top-down control ; zooplankton ; phytoplankton ; nutrients ; internal loading

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract In order to study how pike stocking affects trophic structurepikefingerlings (0–3600 ha−1) were stocked during six yearsineutrophic Lake Lyng (lake area 10 ha), Denmark. Subsequently,marked changes were recorded in the abundance ofzooplanktivorousfish, catch per unit effort of roach, which was the dominantfishspecies, thus varied from 17 to 272. Simultaneously, markedchangeswere recorded in the abundance and relative composition ofzooplankton. Daphnia abundance ranged from 7 to 36 ind.l−1 and Bosmina from 2 to 99 ind. l−1, meansummerabundance of Daphnia being highest and Bosminalowestin years with low fish density. Additionally, cyclopoidcopepod androtifer abundance correlated significantly (p〈0.05,r2=0.70 and 0.83, respectively) andpositively withfishabundance. Mean summer chlorophyll a correlatedsignificantly(p = 0.04, r2=0.70) with theabundanceofroach, suggesting an impact on phytoplankton level also,disregarding that the phytoplankton biomass was dominated byfilamentous cyanobacteria. Total phosphorus concentration waslowest in years with low zooplanktivorous fish abundance,which ishypothesized to be due to lower sedimentation of organicmaterialand lower phosphorus release from the sediment in years withhighzooplankton grazing on phytoplankton. It is concluded thatpikestocking can be used as a lake restoration tool to increaselakewater transparency by creating a trophic cascade. The effectofstocking, however, seems to last only during the season inwhich ithas been undertaken, the impact being most significant at highstocking densities. The method is therefore regarded to bemostuseful in shallow, turbid lakes in which the nutrient loadinghasbeen sufficiently reduced to allow a substantial and permanentmacrophyte coverage if clearwater conditions areestablished.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1017084600712

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4

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Interactions between piscivores, zooplanktivores and zooplankton in submerged macrophytes: preliminary observations from enclosure and pond experiments (1997)

Jacobsen, Lene ; Perrow, Martin R. ; Landkildehus, Frank ; [et al.]

Springer

Hydrobiologia 342-343 (1997), S. 197-205

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ISSN: 1573-5117

Keywords: predator/prey interactions ; refugia ; indirect effects ; Esox lucius ; Perca fluviatilis ; Rutilus rutilus ; Daphnia

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The effects of piscivores upon zooplanktivore behaviour anddistribution and the impact of zooplanktivores on the abundance anddistribution of zooplankton are well documented. However, thepotential indirect effect of piscivores reducing the predationpressure upon grazing zooplankton through behavioural changes ofzooplanktivores has received little attention, even though this maybe an important mechanism in enhancing the stability of submergedmacrophytes in shallow lakes. Preliminary observations from anunreplicated large-scale field enclosure experiment and areplicated pond experiment suggest that this mechanism is plausiblewith the set of piscivores (pike Esox lucius and perch Perca fluviatilis) and the zooplanktivores (0+ roach Rutilusrutilus and perch) common in temperate Europe. The presence ofpiscivores typically changed the habitat use and the activity levelof zooplanktivores and the presence of zooplanktivores typicallychanged the habitat selection of cladoceran zooplankton. In thecase of piscivore/zooplanktivore interactions, the risk ofpredation was enough to generate clear responses even where thelosses to predation were low. However, only in the enclosureexperiment was an indirect impact of the presence of piscivores,enabling Daphnia spp. to utilise open water in the presenceof a high density of zooplanktivorous fish observed. Whether themagnitude and direction of the effect of piscivores is sufficientto benefit zooplankton may depend on the functional group (capableof foraging within structured habitats) of the predator (bothpiscivore and zooplanktivore), absolute and relative densities ofpredator and prey and predator dietary choice.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1017032020760

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5

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Pike (Esox lucius L.) stocking as a biomanipulation tool 1. Effects on the fish population in Lake Lyng, Denmark (1997)

Berg, Søren ; Jeppesen, Erik ; Søndergaard, Martin

Springer

Hydrobiologia 342-343 (1997), S. 311-318

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ISSN: 1573-5117

Keywords: biomanipulation ; pike stocking ; predation ; 0+planktivores ; pike mortality ; pike/perch interaction

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract From 1990–1993 juvenile pike (Esox lucius) were stockedeach spring in the eutrophic Lake Lyng (9.9 ha, max. depth 7.6 m,mean depth 2.4 m) in densities between 515 and 3616 pikeha−1. In 1989–90 the fish population consisted mainly ofroach (Rutilus rutilus), rudd(Scardinius erythrophthalmus), perch (Percafluviatilis) and ruffe (Gymnocephalus cernuus), andtotal fish biomass was estimated at 477 kg ha−1. Prior tostocking pike was not present in the lake. Following the first year ofstocking, the density of roach, rudd and ruffe fry expressedas catch per unit effort decreased significantly by 64 to 97%.In 1991 ruffe disappeared completely. The pike stocking did notaffect the density of perch significantly.The growth of pike was high and also the growth of perchincreased significantly from 1990 to 1991 (p〈0.001) and from1991 to 1994 (p〈0.001). We found a linear negativerelationship between stocking density of pike in May or June and theabundance of juvenile planktivorous fish (r 2=0.85, p〈0.05) in the littoral zone in August. No relationship was found inthe pelagic zone (r 2=0.21, p〉0.4). Pikesurvival was low in late August/early September. We suggest that growthof the piscivorous perch increased due to increased Secchi depthand a continuous high density of 0+ planktivores in the pelagiczone of the lake during the years of pike stocking, possibly caused bybehaviourial changes and the forcing of the 0+ planktivoresinto the pelagic zone.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1017032616642

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6

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Utilization of natural and artificial habitats by YOY pike in a biomanipulated lake (1999)

Skov, Christian ; Berg, Søren

Springer

Hydrobiologia 408-409 (1999), S. 115-122

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ISSN: 1573-5117

Keywords: YOY ; Esox lucius ; artificial habitats ; natural habitats ; biomanipulation ; Point Abundance Sampling by Electrofishing (PASE)

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Biomanipulation by stocking with YOY pike Esox luciushas been shown to be a useful tool in the restoration of shallow hypertrophic lakes. The success of such stocking depends partly on the standing stock of the YOY pike in the first 2–3 months following stocking, this in turn depending on habitat type and abundance in the lake. The present study evaluated the general habitat use and preferences of YOY pike and the suitability of artificial submerged habitats formed by small laid out spruce trees Picea omoricausing Point Abundance Sampling by Electrofishing (PASE). This sampling method was assessed as being suitable for catching and quantifying small pike. While very few pike were present in either the dominant emergent vegetation Phragmites australisor the subdominant vegetation Typhaspp. in June and July, they were present in significantly greater numbers in the artificial habitats. This suggests that the use of spruce trees as artificial habitats in biomanipulation projects could potentially enhance the standing stock of YOY pike. In August, in contrast, habitat utilization by the YOY pike did not differ from that expected if they used the habitats randomly. This suggests that YOY pike change their habitat utilization as a function of their size. Thus they use habitats with a complex structure in the early summer, but in late summer when they are larger, they use habitats with a less complex structure such as Phragmitesand Typha.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1017043015547

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