Inferences about Perception in Large Cetaceans, Especially Humpback Whales, from Incidental Catches in Fixed Fishing Gear, Enhancement of Nets by “Alarm” Devices, and the Acoustics of Fishing Gear

The incidental entrapment of non-target species in fishing gear is a problem of increasing concern for the fishermen and fishery managers of Newfoundland. By-catches of marine mammals however is not a problem unique to Canadian waters. Worldwide, thousands of cetaceans or pinnipeds collide with gear and are caught every year (Perrin, 1988; Fowler, 1988; Bonner, 1982). The problem causes considerable losses to fishing crews and such by-catch may seriously effect populations (Lien et al., 1989a). In addition, for many such losses are ethically and socially undesirable (Lien, 1989). In spite of these concerns, very little is known about the factors which result in cetacean collisions with fishing gear, the whale’s ability to detect gear or the factors which impede detection.