Strong correspondence between gillnet catch per unit effort and hydroacoustically derived fish biomass in stratified lakes

Emmrich, Matthias; Winfield, Ian J.; Guillard, Jean; Rustadbakken, Atle; Verges, Charlotte; Volta, Pietro; Jeppesen, Erik; Lauridsen, Torben L.; Brucet, Sandra; Holmgren, Kerstin; Argillier, Christine; Mehner, Thomas. 2012 Strong correspondence between gillnet catch per unit effort and hydroacoustically derived fish biomass in stratified lakes. Freshwater Biology, 57 (12). 2436-2448.

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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.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Topics & Objectives 2009 - 2012 > Water > WA Topic 2 - Ecohydrological Processes > WA - 2.3 - Assess the responses of river, lake and wetland ecosystems to ecohydrological drivers
UKCEH and CEH Sections/Science Areas: Parr
ISSN: 0046-5070
Funders/Sponsors: European Commission
Additional Information. Not used in RCUK Gateway to Research.: This document is the author’s final manuscript version of the journal article, incorporating any revisions agreed during the peer review process. Some differences between this and the publisher’s version remain. You are advised to consult the publisher’s version if you wish to cite from this article. The definitive version is available at
Additional Keywords: biomass estimates, fish sampling, gillnets, lakes, vertical hydroacoustics
NORA Subject Terms: Ecology and Environment
Date made live: 27 Sep 2012 10:51 +0 (UTC)

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