Mixed fortunes: contrasting status, trends in abundance and management issues for South Australian pinnipeds

Pinnipeds in southern Australia were subject to unrestricted sealing in the early 1800s from which they have yet to recover. Censuses of pup abundance have recently been undertaken throughout South Australia (SA) for... [ view full abstract ]

Pinnipeds in southern Australia were subject to unrestricted sealing in the early 1800s from which they have yet to recover. Censuses of pup abundance have recently been undertaken throughout South Australia (SA) for long-nosed and Australian fur seals, and for Australian sea lions. Results from these, in conjunction with data from long-term monitoring sites, indicate that pup production in the long-nosed fur seal has increased 3.5 fold over the last 24 years and now numbers ~20,400. Australian fur seals have recently colonised SA, with breeding first recognised in 2007. Pup production has increased steadily and was estimated to be 85 in 2014, with the species now recorded to breed at four sites in SA. Australian sea lions are unusual for having a non-annual (~18 month) breeding interval and an asynchronous breeding habit. Pup production per breeding cycle is estimated to number ~2,500 in SA. Based on several monitored sites, it has declined by >50% over the last 37 years. Continued interactions with human activities and differences in life-history traits appear to account for the contrasting status and management issues for fur seal and sea lion populations in SA. For fur seals, there is now growing concern from the seafood (wild fisheries, finfish aquaculture) and some ecotourism (little penguins, giant cuttlefish) industries that populations are overabundant and that their impacts need to be managed. To address these perceptions, projects are currently underway to investigate the importance of commercial fish and finfish aquaculture species in fur seal diet, and develop trophic models to assess the impact of consumption on current and future seafood production. For sea lions, there is now strong evidence that fisheries bycatch mortality, especially in the shark gillnet fishery, has impacted the recovery of the species, and resulted in recent declines observed in some colonies. Management measures to mitigate bycatch have been introduced into the fishery since 2010 and include observer programs, fishery closures, bycatch trigger limits and incentives to switch to alternative fishing methods. These measures will hopefully be sufficient to enable populations to recover, but given the life history of the species, may take decades to detect.