Harbour porpoise (Phocoena phocoena) caught in herring weir (fish trap). Porpoises trapped in herring weirs often die as a result of efforts to remove them (by 'seining' the weir as shown here) but latterly cooperation between fishermen and researchers has improved the situation. Five porpoises were trapped in this weir and none were thought to have survived this operation. Grand Manan, Bay of Fundy, Canada

cetaceans mammals harbour porpoise phocoena phocoena caught in herring weir tangled caught trap trapped fish trap porpoises herring weirs seining weir fisherman fishing commercial fishing fishermen researchers north america grand manan bay of fundy canada high angle view fishing boat