Shaughnessy, Peter D, Simon D Goldsworthy, Derek J Hamer, Brad Page, and Rebecca R McIntosh. 2011. "Australian sea lions Neophoca cinerea at colonies in South Australia: distribution and abundance, 2004 to 2008." Endangered Species Research 13 (2):87-98.
Abstract:The Australian sea lion Neophoca cinerea is an endemic species listed as vulnerable under the Commonwealth ‘Environment Protection and Biodiversity Conservation Act’ and as Endangered by IUCN. Assessing its abundance is difficult because of its supra-annual (17 to 18 mo) breeding cycle, and pupping seasons that are extended (about 6 mo but varying between colonies) and asynchronous in their timing between colonies. Based mainly on surveys at most sites in South Australia (SA) between 2004 and 2008, and information from the literature, estimates of abundance are provided for 39 breeding colonies and 9 haulout sites where pups are recorded occasionally. From this study it is estimated that in SA, 3119 Australian sea lion pups are born per breeding cycle, an increase on former estimates by at least 16% resulting from recognition of new breeding colonies, targeting surveys to coincide with maximum pup numbers and using mark-recapture procedures at some colonies. With the addition of 503 pups in Western Australia, the overall estimate of pup abundance for the species is 3622. This leads to an estimate of 14 780 animals using the multiplier 4.08. Trend data for the Seal Bay colony on Kangaroo Island indicated that pup numbers decreased at 0.54% yr–1 in the 22 yr (16 pupping seasons) from 1985 to 2007. A cause of the decrease is believed to be bycatch in the demersal shark gillnet fishery, which overlaps with sea lion foraging areas nearby. Area closures declared during 2010 within several km of all Australian sea lion breeding sites in SA should reduce the incidence of bycatch mortality.