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A comparative study of three different methods for assessing fish communities in a small eutrophic lake
Author(s) -
Ravn Henrik Dalby,
Lauridsen Torben Linding,
Jepsen Niels,
Jeppesen Erik,
Hansen Peter Gruth,
Hansen Johan Gruth,
Berg Søren
Publication year - 2019
Publication title -
ecology of freshwater fish
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 55
eISSN - 1600-0633
pISSN - 0906-6691
DOI - 10.1111/eff.12457
Subject(s) - rutilus , electrofishing , perch , abundance (ecology) , fishery , species richness , biology , sampling (signal processing) , biomass (ecology) , ecology , catch per unit effort , population , fish <actinopterygii> , population dynamics of fisheries , demography , filter (signal processing) , sociology , computer science , computer vision
Sound decisions on the management of fish stocks depend on knowledge about the species composition, number, biomass and size structure of existing populations. Accordingly, the ability to make solid population estimates is essential. In this study, a 2.15 ha lake was completely drained and the total number of fish was recorded and amounted to 180,915 individuals divided into seven species having a total weight of 1,395 kg. Before the draining, three commonly used methods in fish surveys were applied: multi‐mesh gillnets, point abundance sampling by electrofishing (PASE) and mark–recapture. Following the determination of the actual number and size distribution of each species, we evaluated the efficiency of the methods and found that gillnets caught a relatively high number of species (five out of seven) and thus proved to be the best tool for mapping species richness. However, gillnets were size selective towards larger individuals of perch ( Perca fluviatilis ) and did not catch roach ( Rutilus rutilus ) <5 cm. In contrast to gillnets, PASE was very effective at catching YOY fish in the shore zone but selected for larger‐sized roach. In sum, gillnetting proved to be the most accurate method for estimating species composition, PASE also being useful. Overall, mark–recapture provided relatively good estimates of population size but small‐sized (<11 cm) roach proved not to be well suited for mark–recapture surveys. We conclude that the best method(s) surveying fish stocks depends on various factors such as target species, size distribution and the purpose of the survey.