Obstacles to prevent grey seals (Halichoerus grypus) from entering static fishing gear

No abstracts are to be cited without prior reference to the author.

A series of obstacles aimed to hinder seals from entering set fish traps were tested in the seal aquarium of the Kolmården Wild Animal Park, Sweden. The obstacles were mounted in the opening of a box simulating the entrance of a static fishing gear. Fish (herring) were released into the box through a feeding pipe. The trials were monitored by a 3-camera digital video system. The seven constructions tested were all of the same overall dimensions (450 x 450 mm). Each obstacle was tested twenty times. There were three grey seals in the aquarium. The activity was intense and all fishes were taken sooner or later. Neither construction fully hindered the seals to take the fish. There was however significant differences in the number of attempts required taking the fish, the distance, which seals could reach into the box and the time it took to take the fish. Most attempts to take the baits were made by one individual, an adult female. Two obstacles could be modified to efficiently prevent seals to enter.