Fish preference by the harbour seal (Phoca vitulina), with implications for the control of damage to fishing gear

Abstract

This study compares food preference for different fish species by harbour seals in a seal colony off the northwest coast of Sweden. Seals were offered several different species of dead fish in net cages and showed a preference for herring, gadids and flatfish. Other fish such as eel and eelpout were mostly rejected. Five-bearded rockling, bullrout and small labrids were always rejected. Seal visits occurred at only 30% of the total number of feeding opportunities, in spite of the fact that seals were constantly present in the area. The temporal and spatial aggregation of the pattern of seal visits to the cages was not randomly distributed. This study suggests that only a minority of the seals in the area used the baited cages and that the feeding preferences could be a result of specialised prey selection. This has important implications for the choice of appropriate management options to control seal damage of fishing gear. It is predicted that it may be a more successful and efficient option to focus on those individual seals found in the vicinity of the fishing gear, rather than to carry out random culling amongst the whole population.