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Strong correspondence between gillnet catch per unit effort and hydroacoustically derived fish biomass in stratified lakes
Author(s) -
EMMRICH MATTHIAS,
WINFIELD IAN J.,
GUILLARD JEAN,
RUSTADBAKKEN ATLE,
VERGÈS CHARLOTTE,
VOLTA PIETRO,
JEPPESEN ERIK,
LAURIDSEN TORBEN L.,
BRUCET SANDRA,
HOLMGREN KERSTIN,
ARGILLIER CHRISTINE,
MEHNER THOMAS
Publication year - 2012
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/fwb.12022
Subject(s) - pelagic zone , sampling (signal processing) , biomass (ecology) , fishery , environmental science , trophic level , benthic zone , fishing , fish <actinopterygii> , catch per unit effort , demersal fish , target strength , trawling , electrofishing , ecology , biology , filter (signal processing) , computer science , computer vision
Summary 1. Sampling of lake fish assemblages is a challenging task in fish science, and the information obtained strongly depends on the choice of sampling gear. The use of more than one sampling technique is generally preferred in order to achieve a comprehensive view on fish assemblage structure. Therefore, the knowledge of whether catches between fishing gears are comparable is crucial. 2. We compared catches in benthic multi‐mesh gillnets with fish biomass estimates obtained by vertical hydroacoustics in 18 European lakes strongly varying in morphometry and trophic status. Separate analyses were conducted for different depth strata and for several fish length thresholds to account for depth‐ and size‐selective gillnet catches. 3. Gillnet catches and hydroacoustically obtained fish biomass estimates were significantly correlated. The strength of correlations was independent of the fish length thresholds applied, but varied across different depth strata of the lakes, with the strongest correlations occurring in the shallow strata. 4. The results support the applicability of vertical hydroacoustics for the quantification of fish biomass in stratified lakes. Survey designs combining hydroacoustics with limited gillnetting at sampling dates shortly one after the other, the latter for the purpose of inventory sampling only, are a cost‐effective strategy for sampling fish assemblages in lakes. However, gillnet sampling does not provide reliable fish density estimates in very deep lakes with separate, pelagic‐dwelling fish assemblages.