Density and temperature dependence of gill net catch per unit effort for perch, <i>Perca fluviatilis</i>, and roach, <i>Rutilus rutilus</i>

Linløkken, Arne; Haugen, Thrond O.

doi:10.1111/j.1365-2400.2006.00502.x

Cited by 50 publications

(61 citation statements)

References 32 publications

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“…In roach from gill net catches (body lengths 137 -290 mm), the mean δ 15 N value was similar to small perch, i.e. approximately also observed in other lakes with these species (Brabrand & Borgstrøm 2000;van Dijk et al 2002;Linløkken & Haugen 2006). Burbot and Arctic charr, on the other hand, often staying in deeper water with lower temperatures (Hofmann & Fischer 2002;Klemetsen et al 2003), may have a lower catchability by gillnetting, and thereby a lower CPUE due to low temperatures (Borgstrøm 2000).…”

Section: Discussionsupporting

confidence: 75%

“…Apparently, the population density of Arctic charr in Lake Skasen is very low, but still catch data from one particular spawning site indicate that the mean body weight of spawners have decreased from approximately 218 g in 1992 -1996 to 91 g in 2006-2007, probably demonstrating that the population is squeezed due to interactions with other species. With the confined use of the profundal habitat of Arctic charr in Lake Skasen, intraspecific interactions may be important for the population dynamics, as observed in Lake Lønavatn, Western Norway (Jonsson & Østli 1979).…”

Section: Discussionmentioning

confidence: 97%

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Arctic charr (Salvelinus alpinus) squeezed in a complex fish community dominated by perch (Perca fluviatilis)

Sandlund

Haugerud²,

Rognerud³

et al. 2013

Fauna Norv.

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Sandlund OT, Haugerud E, Rognerud S and Borgstrøm R. 2013. Arctic charr (Salvelinus alpinus) squeezed in a complex fish community dominated by perch (Perca fluviatilis). Fauna norvegica 33: 1-11.In the complex fish community of Lake Skasen, southeastern Norway, the relative population density, habitat use and diet of Arctic charr, perch, roach and burbot was studied by a gill net survey during June-September 2010. A marked segregation in habitat use was observed, with Arctic charr and burbot captured in the profundal and deepest part of the pelagic habitat, and perch and roach captured in the littoral and upper part of the pelagic. Perch dominated the total catches, followed by roach. Arctic charr occurred in low numbers in the catches, and also had a low annual growth rate. Even in June, at low water temperatures, Arctic charr were confined to the profundal. Both Arctic charr, roach and perch fed on the same cladocerans, but all size groups of perch had fish as an important part of the diet. Analysis of stable carbon and nitrogen isotopes revealed a narrow trophic niche of Arctic charr, positioned at the extreme pelagic end of the carbon gradient relative to the other fish species. These had a wider span of δ 13 C signatures, but more positioned towards the littoral end of the carbon gradient. The low growth rate of Arctic charr, despite a low population density, indicates that food is a limiting resource for charr in this lake, probably due to a confinement to the profundal habitat as a result of competition and predator avoidance. Since all age-classes of Arctic charr seem to be enclosed in the profundal habitat, intraspecific competition and predation may be supplementary stressors resulting in low annual recruitment and low population density, as well as low individual growth rate, i.e. the population is squeezed. The narrow trophic niche of Arctic charr compared to perch, roach and burbot, revealed by stable isostope analysis, supports this conclusion.

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Section: Discussionsupporting

confidence: 75%

Section: Discussionmentioning

confidence: 97%

Arctic charr (Salvelinus alpinus) squeezed in a complex fish community dominated by perch (Perca fluviatilis)

Sandlund

Haugerud²,

Rognerud³

et al. 2013

Fauna Norv.

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“…Other comparable studies [15,20] did not report any symptoms of prominent changes in species proportions when comparing data for 1*12 h vs. 3*4 h treatments and overnight vs. 1 h treatments, respectively. Contrary to our findings, even decreasing catchability with increasing density particularly for perch and to a lesser extent with roach has been found [9]. These species-specific differences definitely require further study.…”

Section: Discussioncontrasting

confidence: 55%

“…Unfortunately, this assumption typically does not hold for passive gill nets. Several studies [5][6][7][8][9][10] have reported a negative relationship between gill net catchability and abundance, and consequently CPUE may even appear asymptotically related to abundance.…”

Section: Introductionmentioning

confidence: 99%

Empirical Estimation of Accumulation-Induced Change in Gill Net Catchability: Mind the Observation Errors

Marjomäki¹,

Paloniemi²,

Keskinen³

et al. 2015

TOFISHSJ

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Abstract:We analyzed cumulative catches for 24 h gill net exposures divided into 4*6 h, 2*12 h and 1*24 h soak time treatments to estimate the reduction in its catchability due to accumulation of fish. The effects of loss of catch during net lifting, disturbance effect and fouling were eliminated as far as possible to reveal the true effect of accumulation. First we applied simple nonparametric and parametric tests in comparison of treatments. As expected, considerable reduction in catchability took place along with the increase in soak time, indicated by significantly lower total 24 h catches from longer soaks in comparison with shorter ones. The reduction was more pronounced for roach than for perch. Further, we compared a functional relationship regression (FRR), admitting correctly observation error variance also in the x-axis variable, with ordinary least squares regression (OLS) in modelling the relationship between cumulative 24 h catches for different treatments. We estimated the between-replicates proportional observation error variance within a treatment and found it to be similar in different treatments. Therefore the variance ratio could be assumed to be close to 1 enabling the use of major axis solution FRR. In this particular case the incorrect use of OLS obviously gives a seriously biased result, exacerbating the negative effect of accumulation for high x-axis values in comparison with FRR. We recommend the use of FRR for any analysis comparing different notoriously low precision fish abundance proxies.

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“…The gillnet CPUE was higher at night probably due to higher activity of fish. Activity as a factor in increasing gill net catches has already been well described (Hamley 1975;Rudstam et al 1984;Linløkken and Haugen 2006). In addition, the gill-net is less visible in the dark, thus reducing fish avoidance and increasing catches.…”

Section: Discussionmentioning

confidence: 84%

Discriminating the diel vertical migration of fish andChaoborus flavicanslarvae in a lake using a dual-frequency echo sounder

Knudsen

Larsson

2009

Aquat. Living Resour.

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-The diel vertical migration of fish and larvae of the phantom midge Chaoborus flavicans was studied using a combined 38 and 200 kHz echo sounder. Multi-mesh gill net was used to sample fish, and a Schindler-Patalas trap to sample Chaoborus. Oxygen and temperature profiles were also recorded. At 38 kHz, only fish were detected, without considerable interference from Chaoborus echoes. At 200 kHz, both fish and Chaoborus were detected and echoes from Chaoborus almost completely masked all fish echoes at night. During the day, Chaoborus remained hidden in an oxygen-poor refuge near the bottom. Tracks of fish diving into the Chaoborus refuge were observed on several occasions. At the onset of dusk, Chaoborus started to rise and by the time it was dark they were occupying the whole water column. Fish were found in patches in midwater during the day. In the dark, the fish were dispersed throughout the water column. Results suggest that a dual-frequency approach can be used to discriminate between fish and Chaoborus and to provide a rapid method for their selective monitoring.

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Density and temperature dependence of gill net catch per unit effort for perch, Perca fluviatilis, and roach, Rutilus rutilus

Cited by 50 publications

References 32 publications

Arctic charr (Salvelinus alpinus) squeezed in a complex fish community dominated by perch (Perca fluviatilis)

Arctic charr (Salvelinus alpinus) squeezed in a complex fish community dominated by perch (Perca fluviatilis)

Empirical Estimation of Accumulation-Induced Change in Gill Net Catchability: Mind the Observation Errors

Discriminating the diel vertical migration of fish andChaoborus flavicanslarvae in a lake using a dual-frequency echo sounder

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