Spatial and temporal patterns of sperm whale (Physeter macrocephalus) depredation on Australian longline vessels in the Patagonian toothfish (Dissostichus eleginoides) fishery at Heard Island and McDonald Islands (CCAMLR Division 58.5.2)

Incidence of odontocete depredation, involving sperm whales (Physeter microcephalus) and orcas (Orcinus orca) has been reported in nearly all of the Patagonian toothfish (Dissostichus eleginoides) longline fisheries in the Southern Ocean (Moir Clark and Agnew 2010, Tixier et al 2010, Soeffker and Tixier 2015, Söffker et al. 2015). The first reports of odontocete depredation in the Division 58.5.2 fishery date from 2011, and incidences have been reported in every season thereafter. The majority of  reports involve sperm whales, with a single sighting of orcas to date. There is a strong seasonal pattern to sperm whale presence, with depredation events confined to the months April-July, despite longlining activity occurring April-November. Currently, all vessels mitigate depredation by hauling lines once sperm whales are sighted, and steaming over 50 nautical miles before resetting gear. A collaborative project with depredation experts from France is currently being developed to monitor depredation behaviour across the Kerguelen Plateau and explore options for long term mitigation