Knowledge of the diet of the Australian sea-lion (Neophoca cinerea) has been restricted to anecdotal, qualitative accounts. In this study, we tested the validity of using identifiable prey remains in scats to quantify the diet of N. cinerea by analysis of scats from free-ranging sea-lions and feeding trials on captive sea-lions. Identifiable remains in the scats of free-ranging animals occurred infrequently: otoliths (n = 8) were present in only 9% of scats, cephalopod beaks (n = 23) in only 24% and lobster (Panulirus cygnus) remains in 7%. These limited data, combined with analysis of contents of five stomachs, indicated that N. cinerea has a broad diet and feeds on some benthic species. Feeding trials on two captive sea-lions demonstrated that scats were not representative of the diet. Fewer than 2% of ingested otoliths (by number) were recovered in scats. Otoliths less than 5 mm long were absent from scats; recovery of larger otoliths increased with their size. Defaecated otoliths were eroded by at least 28% (by length) during digestion. Transit of cephalopod mouth parts in two captive animals was variable (98% and 9% recovery), with only beaks of small cephalopods passing through the pyloric canal. The complete digestion of otoliths in transit through the gut tract and the variable recovery of cephalopod beaks indicated that scats cannot be used even for a qualitative description of the diet of

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.

Body size and food intake of four female and three male captive Indian Ocean bottlenose dolphins, Tursiops truncatus, were recorded regularly over a 10-year period. Growth of three captive-born female calves was also recorded. Growth of females parallelled that of South African bottlenose dolphins, tending toward an asymptote of c. 240 cm at 16 years of age. Growth of males was characterised by a secondary growth spurt at puberty between the ages of 10 and 12 years. Wild-caught females were approximately 10% heavier for age than their South African conspecifics. The captive-born females were up to 50% heavier than their African counterparts. Growth rates of females and males were 2.1-2.6 cm per year and 2.0-2.6 cm per year, respectively, between the ages of 3 and 16 years. Females were known to be reproductively mature at 11-13 years of age when lengths were between 227 and 238 cm. DNA fingerprinting of offspring and potential parents revealed that one of the three males was reproductively mature at 233 cm and another at either 222 or 226 cm. One of the males was sexually mature at the beginning of its secondary growth spurt at 10 or 11 years of age. Food intake of dolphins increased significantly with decreasing water temperature. It is suggested that variations in water temperature and food availability may play a role in governing body-size differences between T. truncatus populations.