Entanglements of baleen whales off the coast of Western Australia between 1982 and 2010: patterns of occurrence, outcomes and management responses.

Abstract

Baleen whale population sizes have increased in Western Australian waters since the cessation of commercial whaling activities. This has been followed by a coincident increase in the number of reported entanglements of baleen whales in fishing gear. During their annual migration, whales pass through Western Australian waters used by commercial fisheries targeting rock lobster, octopus and shark as well as aquaculture industries producing abalone, pearls and mussels. We reviewed the 63 baleen whale entanglement records in the Western Australian Cetacean Strandings Database (1982-2010). Of the four baleen whale species observed entangled in fishing gear in Western Australian waters, the Humpback Whale Megaptera novaeangliae accounted for 56 (89%) entanglements, followed by the Southern Right Whale Eubalaena australis, five (8%) entanglements, and one record each for both the Bryde s Balaenoptera edeni and Minke Whale Balaenoptera acutorostrata. Almost half of entanglements occurred in rock lobster fishing gear (n = 31; 49%). There is an upward trend in the number of entanglements reported since 1990 in rock lobster fishing gear despite fishing effort reducing over the same period of time. This can, at least partly, be attributed to the increase in humpback whale population size. Fisheries and conservation agencies have responded by developing cooperative relationships and protocols that reduce entanglement risk and improve outcomes when entanglement does occur.