Avoidance reactions of herring to a survey vessel, studied by scanning sonar
Original version
This report is not to be cited without prior reference to the authorsAbstract
The behavioural response of a shallow herring layer to a steaming
vessel has been studied by the use of a high-resolution scanning sonar
technique. When the vessel was completely darkened, no significant
reaction important for biomass estimation was observed, either at
three or at nine knots speed. With usual deck lights, however, the
reaction was severe, and the integrator system strongly
underestimated the true herring density.