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Research article - Peer-reviewed, 2019

Including 38 kHz in the standardization protocol for hydroacoustic fish surveys in temperate lakes

Mouget, Anne; Goulon, Chloe; Axenrot, Thomas; Balk, Helge; Lebourges-Dhaussy, Anne; Godlewska, Malgorzata; Guillard, Jean

Abstract

Hydroacoustics has become a requisite method to assess fish populations and allows to describe the relationships of fish with other elements of the aquatic ecosystem. This nonintrusive method is currently an integral part of the sampling procedures recommended for fish stock assessment by the Water Framework Directive and has been standardized by the European Committee for Standardization [CEN (2014) CSN EN 15910 - Water quality - Guidance on the estimation of fish abundance with mobile hydroacoustic methods, Category: 7577 Water quality. Biological.]. In Europe, hydroacoustic surveys are performed in freshwater using different frequencies. Consequently, there is a need to evaluate if survey results can be compared. This study aimed to carry out in situ comparisons at the 38 kHz frequency (noted f) with two other commonly used frequencies, 70 and 200 kHz. The 38 kHz frequency has seldom been compared with other frequencies in freshwater although it is widely used worldwide, especially in the Great Lakes of North America and in Sweden. In 2016, hydroacoustic data were acquired in Lakes Annecy and Bourget using methods validated in previous studies that compared the frequencies 70, 120 and 200 kHz. This study showed similar density and biomass estimations as a function of frequency, density(f) and biomass(f), between the frequencies studied for low to moderate fish densities. For higher fish densities, the results were more variable and need to be verified. Fish density(f) and biomass(f) estimations sometimes exhibit differences between frequencies, which is not fully in agreement with theoretical calculations. The aim of this study was to evaluate frequency comparisons in practise. However, if the differences on acoustic metrics, density(f) or biomass(f) between frequencies were occasionally statistically significant, the differences were small enough to be considered negligible for fish population management. These analyses led to better knowledge of the responses from fish in temperate lakes for the studied frequencies. Our findings should be considered when revising the CEN standard.

Keywords

Fisheries acoustics; frequencies comparison; freshwater; hydroacoustics; lake; standardization

Published in

Remote sensing in ecology and conservation
2019, volume: 5, number: 4, pages: 332-345
Publisher: WILEY

Authors' information

Mouget, Anne
Universite de Savoie
Goulon, Chloe
Universite de Savoie
Swedish University of Agricultural Sciences, Department of Aquatic Resources
Balk, Helge
University of Oslo
Lebourges-Dhaussy, Anne
Institut de Recherche pour le Developpement (IRD)
Godlewska, Malgorzata
Polish Academy of Sciences
Guillard, Jean
Universite de Savoie

UKÄ Subject classification

Fish and Aquacultural Science

Publication Identifiers

DOI: https://doi.org/10.1002/rse2.112

URI (permanent link to this page)

https://res.slu.se/id/publ/109239