No evidence for recovery in the population of sperm whale bulls off Western Australia, 30 years post-whaling

Published source details Carroll G., Hedley S., Bannister J., Ensor P. & Harcourt R. (2014) No evidence for recovery in the population of sperm whale bulls off Western Australia, 30 years post-whaling. Endangered Species Research, 24, 33-43.
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This study is summarised as evidence for the following.

	Action	Category
	Prohibit or restrict hunting of marine and freshwater mammal species Action Link

Prohibit or restrict hunting of marine and freshwater mammal species

A before-and-after study in 1968–1978 and 2009 of a pelagic area in the Southern Ocean, Western Australia (Carroll et al. 2014) found that 31 years after legislation to prohibit hunting was introduced, the number of mature male sperm whales Physeter macrocephalus in the area did not differ significantly compared to before protection. The average number of mature male sperm whales observed in the area did not differ significantly before (6–13 whales/survey) or 31 years after hunting was prohibited (2–3 whales/survey). However, the authors state that other factors may have limited population recovery (e.g. entanglement in fishing nets, chemical and noise pollution). The sperm whale population had declined by 74% in 1955–1978 due to commercial whaling. Full legal protection was put in place after 1978 to prohibit whaling. Data for before protection were collected by aircraft used to assist in hunting whales in 1968–1978. Aircraft flew over the area at 1,500 feet and observers recorded mature male sperm whales (>11 m long) during 42–73 surveys/year. The same area was surveyed in September–December 2009 (21 surveys) using similar methods and a standard grid of 12 transects to provide comparable data 31 years after protection was put in place.

(Summarised by: Anna Berthinussen)