Incidental catch of marine birds and mammals in fishing nets off Newfoundland, Canada

Summer surveys of the incidental catch of marine birds and mammals in fishing nets around the east coast of Newfoundland indicated that over 100 000 animals were killed in nets during a 4-year period (1981–1984). Composition of catches depended on foraging behaviour, regional abundance, and the degree of foraging aggregation of different species. Highest incidental catches occurred in conjunction with the inshore spawning migration of capelin (Mallotus villosus), and the numbers of capelin predators caught varied with capelin abundance. Seabird by-catch was highest in the vicinity of major breeding colonies, decreasing rapidly with distance from these sites. In some years and locations, net-mortality may have constituted the greatest source of adult mortality for some species' populations.