Hostname: page-component-5d84bcc8dc-vpzxz Total loading time: 0 Render date: 2026-09-08T10:17:36.014Z Has data issue: false hasContentIssue false

How pulse lengths impact fish stock estimations duringhydroacoustic measurements at 70 kHz

Published online by Cambridge University Press:  17 March 2011

Małgorzata Godlewska
Affiliation:
Stanislaw Sakowicz Inland Fisheries Institute, Oczapowskiego 10, 10-719 Olsztyn, Poland International Institute of the Polish Academy of Sciences, European Regional Centre for Ecohydrology under the auspices of UNESCO, Tylna 3, 90-364 Łódź, Poland
Michel Colon
Affiliation:
INRA, UMR CARRTEL, BP 511, 74203 Thonon les Bains, France
Adam Jóźwik
Affiliation:
Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, ul. Ks. Trojdena 4, 02-109 Warszawa, Poland
Jean Guillard*
Affiliation:
INRA, UMR CARRTEL, BP 511, 74203 Thonon les Bains, France
*
a Corresponding author:guillard@thonon.inra.fr
Get access

Abstract

Water Framework Directive requires reliable and effective monitoring tools, andhydroacoustics has a potential to be one of them. The effect of pulse duration onin situ acoustical estimates of fish density and their sizedistribution was investigated. Measurements were performed in the oligo-mesotrophic LakeHancza (Poland) using a SIMRAD EK60 split-beam echo-sounder at 70 kHz frequency. Duringthe survey, two similar transducers pinged alternatively through the multiplexer using 4different pulse lengths, from short to long ones. The results show that the volumebackscattering coefficient (Sv) values, equivalent of the fish biomass, were notinfluenced by the pulse length. However, the number of the detected fish, the mean targetstrength (TS), and consequently the fish density, differed significantly for the longpulse duration data. This was especially noticeable in the layer above the thermoclinewith dense fish populations. In this upper layer, for the long pulse the Sawada indexfrequently exceeded value of 0.1 leading to overestimation of the mean TS andunderestimation of the fish density.

Information

Type
Research Article
Copyright
© EDP Sciences, IFREMER, IRD 2011

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable