Breeding biology and movements of Australian sea-lions, Neophoca cinerea, off the west coasst of Western Australia

Abstract

The Australian sea-lion, Neophoca cinerea, has a 17-18-month breeding cycle on islands off the west coast of Western Australia. Buller, North Fisherman and Beagle Is are the main pupping sites, with several very small colonies (n> 3) at the Abrolhos Is. The 4-5-month pupping seasons are synchronised at North Fisherman and Beagle Is, but the sea-lions from Buller I. breed one month later and those from the Abrolhos Is two months earlier. Pup production and pup mortality were highly variable between seasons over which observations were recorded: 129 pups were born at the main breeding sites in early 1988, the mortality in the first five months was 7.1%, whereas 181 pups were born in late 1989 of which 24.3% died. Pups remain in the vicinity of their natal islands for the first 4-5 months of life before leaving, perhaps on foraging trips, with their mothers. Most return to their natal island, although others haulout on islands up to 27 km away. Some male N. cinerea congregate in bachelor colonies on islands adjacent to the Perth metropolitan region during the non-breeding season and migrate up to 280 km north each breeding season. The status of the isolated, west-coast N. cinerea population is unknown. The current high level of human pressure on sea-lion terrestrial habitats and their food resources indicate a need for further monitoring of this species.

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

“…Distances among the six South Australian colonies included in this study varied from only a few kilometers to almost 400 km. Clear differences in the genetic composition were observed between the most eastern and western South Australian colonies, which are close to the limit of expected dispersal capabilities (Gales et al, 1992;Lowther et al, 2013). However, significant structuring was also detected between colonies separated by only 120-160 km, well within realistic swimming distances for Australian sea lions.…”

“…Like most pinnipeds, Australian sea lions are capable of longrange movements and have been documented moving up to 350 km (Gales et al, 1992;Lowther et al, 2013). The aim of this study was to determine whether previously observed extreme matrilineal substructure is also evident with biparentally inherited microsatellite markers and whether typical mammalian male-biased dispersal is evident for this species.…”

“…The capacity for long-distance dispersal coupled with asynchrony in the timing of breeding among colonies might have been expected to offer Australian sea lion males a unique opportunity to sire pups throughout much of the year by visiting different colonies. In Western Australia males migrate up to 280 km each breeding season between male haul-out sites and breeding sites (Gales et al, 1992). Similarly, satellite-tracking data from South Australia have shown that genetic divergence lies within the geographic range of regular male foraging trips (on average 170 km per trip, range up to 368 km; Lowther et al, 2013).…”

Review of Underwater and In-Air Sounds Emitted by Australian and Antarctic Marine Mammals

“…They are endemic to Australia, distributed from the Houtman Abrolhos Islands (WA) to The Pages Island (SA; [442]), in waters up to 105 m depth [443]. The species has been known to venture to the southern coast of eastern Australia.…”

Variability in haul-out behaviour by male Australian sea lions Neophoca cinerea in the Perth metropolitan area, Western Australia

“…Breeding takes place aseasonally on average every 17.4 mo (range: 16.0− 19.9 mo) and asynchronously between breeding locations, during a period of 5 to 9 mo (Ling & Walker 1978, Gales et al 1992, Higgins 1993, Goldsworthy et al 2008. Haul-out sites in the Perth metropolitan area (Western Australia), approximately 250 km south of the closest breeding islands at Jurien Bay, are known to be used exclusively by males (Gales et al 1992). Male N. cinerea travel significant distances away from breeding colonies, presumably to maximise foraging success and efficiency (Gales et al 1992).…”