Australian sea lions Neophoca cinerea at colonies in South Australia: distribution and abundance, 2004 to 2008

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.

The Limits of Dispersal: Fine Scale Spatial Genetic Structure in Australian Sea Lions

“…Over 60% of Australian sea lion colonies are defined as "small, " producing fewer than 30 pups per breeding episode (Goldsworthy et al, 2009). Only eight colonies produce more than 100 pups per breeding season and breeding is on a 17-18 month cycle (Higgins, 1993;Shaughnessy et al, 2011). This is in stark contrast to many other otariid species such as New Zealand fur seals where thousands of pups are born annually within large colonies (e.g., Goldsworthy and Shaughnessy, 2013).…”

“…Typically in terrestrially breeding pinnipeds, synchronized breeding across colonies means males can only sire pups from a single colony in any one season and long-term (multi-year) site fidelity imparts a higher degree of success for individual males (Harcourt et al, 2007a). In contrast, the Australian sea lion has a prolonged, 17-18 month reproductive cycle that is asynchronous across its range, even between geographically close colonies (Higgins, 1993;Gales et al, 1994;Shaughnessy et al, 2011). Accordingly, Australian sea lion males could potentially sire pups throughout much of the year by visiting different colonies.…”

“…In the late eighteenth and early nineteenth century the Australian sea lion was subjected to unregulated harvest, resulting in extirpation of colonies in Bass Strait and reduction in numbers within the current range (Ling, 1999;Shaughnessy et al, 2005;Robinson et al, 2008). Unlike the two sympatric fur seal species, the Australian fur seal (Arctocephalus pusillus doriferus) and the New Zealand fur seal (Arctocephalus forsteri), the recovery for Australian sea lions has neither been rapid nor sustained (Shaughnessy et al, 2011). Today, animals are distributed across 76 breeding colonies (18 of these are classified as haul-out sites with occasional pupping) and approximately 86% of pups are born in South Australia, with the remaining 14% in Western Australian colonies (Goldsworthy et al, 2009).…”

“…The current species census estimate of ∼14,700 individuals makes it one of the rarest otariids in the world and listed as endangered on the IUCN "Red List" (Shaughnessy et al, 2011). In the late eighteenth and early nineteenth century the Australian sea lion was subjected to unregulated harvest, resulting in extirpation of colonies in Bass Strait and reduction in numbers within the current range (Ling, 1999;Shaughnessy et al, 2005;Robinson et al, 2008).…”

MOLECULAR DETECTION OF ANTIBIOTIC-RESISTANCE DETERMINANTS INESCHERICHIA COLIISOLATED FROM THE ENDANGERED AUSTRALIAN SEA LION (NEOPHOCA CINEREA)

“…The total population is estimated at ,15,000 animals; the only site monitored in the long-term, Kangaroo Island, shows continual decline (Shaughnessy et al 2011). Australian sea lions breed in at least 76 small, dispersed colonies on islands and some protected coves from Houtman Abrolhos in Western Australia (WA) to The Pages in South Australia (SA) (Shaughnessy et al 2011).…”