Day / night variation in fish directivity in the trawl opening
Original version
This report is not to be cited without prior reference to the authorsAbstract
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.