Distribution, abundance and breeding cycle of the Australian sea lion Neophoca cinerea (Mammalia: Pinnipedia)

Abstract

Surveys of the Australian sea lion Neophoca cinerea were conducted throughout its range in Western and South Australia between December 1987 and February 1992. Almost every island was visited between Houtman Abrolhos and The Pages (n = 255), many of them more than once. Sea lions breed on at least 50 islands, 27 in Western Australia and 23 in South Australia. Of the 50 breeding sites, 31 have not been reported previously. A further 19 islands may also support breeding colonies. A total of 1,941 pups was counted and pup production was estimated at 2,432. Only five colonies produced more than 100 pups each and they accounted for almost half of the pup production. Most of these colonies are near Kangaroo Island, South Australia. A breeding cycle of 17–18 months has been reported for N. cinerea at Kangaroo Island and on the west coast of Western Australia; this was also noted at another 11 islands where repeated visits coincided with breeding. No evidence was found for breeding seasons shorter or longer than 17–18 months. The breeding season was not synchronized between islands, as it is in other pinnipeds. A predictive model is developed to estimate the population size from pup production figures. It indicates that pup numbers should be multiplied by between 3.81 and 4.81 to estimate the total population size just before the pupping season begins. This leads to estimates of 9,300–11,700 for the total population, considerably greater than earlier estimates. Causes of the unique reproductive cycle of N. cinerea are unknown, but we hypothesize that it results from living in a temperate climate in some of the most biologically depauperate waters of the world. It is also clear that day length and water temperature cannot act as exogenous cues for implantation of the blastocyst; the physiological events of gestation must, rather, be cued endogenously.

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

“…Although most Australian sea lion colonies are found in isolated areas or on coastal islands where unlicensed visits are prohibited, three South Australian colonies, Seal Bay, Seal Slide, and Cape Gantheaume, all on Kangaroo Island, experience high levels of human tourist activity and visitation (Gales et al 1994;Shaughnessy 1999). Several haul-outs (nonbreeding sites) in WA are also subject to very high levels of tourist visitation (Orsini et al 2006).…”

“…Although their distribution is broad, individual colonies show limited dispersal, localized foraging by both sexes, and a high degree of population genetic structure (Lowther et al 2012(Lowther et al , 2013. Sea lions are indirectly exposed to terrestrial microorganisms through ingestion of seawater contaminated with wastewater runoff and via behaviors such as hauling-out on beaches used by humans (Gales et al 1994). In addition, as a tourist icon, sea lion colonies in both WA and SA receive high levels of human visitation, with visitor numbers to Seal Bay on Kangaroo Island exceeding 150,000 tourists annually .…”

Historical and modern distribution and abundance of the New Zealand sea lionPhocarctos hookeri

“…This partly reflects the fact that the habitat requirements of the New Zealand sea lion are unknown, but Smith (1989) suggested that as both the Australian sea lion (Neophoca cinerea) and the South American sea lion {Otaria byronia) inhabit lower latitudes (Vaz-Ferreira 1981;Gales et al 1994), then it is possible that the New Zealand sea lion could as well.…”

Inadvertent social information in breeding site selection of natal dispersing birds

“…For instance, at a relatively small-scale, many frog species show higher synchrony when they breed in ponds and less synchrony when they breed in rivers (Vences et al 2002). At a larger spatial and taxonomic scale, all pinnipeds are strikingly synchronous in breeding across their collective familial range except for the Australian sea lion (Neophoca cinerea) that exhibits unique asynchronous breeding both between and within colonies (Gales et al 1994). Perhaps the broadest taxonomic and spatial scales that could be used to test our hypothesis would involve avian migration systems, where breeding synchrony tends to increase with latitude (Baker 1938;Spottiswoode & Møller 2004), usually because of increasingly short breeding seasons.…”