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 three-stage petrochemical evolution of the Steens Basalt (southeast Oregon, USA) compared to large igneous provinces and layered mafic intrusions