Day / night variation in fish directivity in the trawl opening
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Original versionThis report is not to be cited without prior reference to the authors
Still photographs of fish in the mouth area of a bottom trawl were taken by a downwards-oriented automated strobe camera mounted near the headrope. Fish angles relative to the towing direction were measured. Fish were significantly less polarized by night than by day, and in the daytime photographs less polarization was seen at low fish densities than at higher. The results are discussed with regard to fish herding patterns and potential escapement beneath the fishing line of a trawl.