Journal Article

Simulating trawl herding in flatfish: the role of fish length in behaviour and swimming characteristics

Paul D. Winger, Stephen J. Walsh, Pingguo He and Joseph A. Brown

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 61, issue 7, pages 1179-1185
Published in print January 2004 | ISSN: 1054-3139
Published online January 2004 | e-ISSN: 1095-9289 | DOI:
Simulating trawl herding in flatfish: the role of fish length in behaviour and swimming characteristics

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  • Marine and Estuarine Biology


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Theoretical modeling indicates that the herding efficiency of flatfish by bottom-trawl sweeps is highly sensitive to subtle changes in fish behaviour. Yet the degree of variation in herding behaviour within a species, population, or individual remains poorly understood because of the difficulty observing and measuring fish behaviour in this region of the gear. The purpose of this study was to simulate herding under laboratory conditions in order to examine the behaviour and swimming characteristics of flatfish. Using a large flume equipped with a moving floor, we examined the effect of fish length on gait use, behaviour, and swimming kinematics in American plaice (Hippoglossoides platessoides). While swimming at a speed comparable to the herding speed of trawl sweeps (0.3 m s−1), smaller plaice (<30 cm) spent a large percentage of time using the kick-swim gait, while larger fish (≥30 cm) preferred cruising. In total, 65% of plaice exhibited settling behaviour, analogous to the swim-and-settle behaviour observed in response to trawl sweeps. The frequency of this behaviour and the distance swum between settles were independent of fish length. Only the frequency of gliding changed with the duration of swimming. Like other teleost species, tailbeat frequency decreased with increasing fish length. The results from this study indicate that fish length affects gait use and swimming kinematics in flatfish, but not the frequency of gliding and settling behaviours. These observations support the hypothesis of size-selective herding and provide further insight into the herding efficiency of trawl sweeps.

Keywords: behaviour; bottom-trawl; fish length; flatfish; gait use; herding efficiency; kinematics

Journal Article.  3754 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

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