Fur seals and sea lions (family Otariidae) on the breakwaters at Adelaide's Outer Harbor, South Australia

摘要

Long-nosed fur seals (Arctocephalus forsteri) and Australian sea lions (Neophoca cinerea) on the breakwaters at the mouth of the Port River estuary at Adelaide's Outer Harbor were counted from 2004 to 2015. Observed counts were modelled using a generalised linear model. Fur seal numbers have been increasing since 2011; for sea lions there was a small discernible annual trend in counts. Counts of fur seals varied seasonally; most annual maxima were in August or September with modelled peak numbers around 9-11 September. The maximum count of fur seals was 79 in September 2015. For sea lions, the model predicts annual peaks in the period 28 August to 19 September. The maximum count of sea lions was nine in September 2009. The haulout sites on the Outer Harbor breakwaters are easily accessible by boats, including pleasure craft. In particular, the seaward end of the outer breakwater is a popular spot with recreational anglers whose lines are often within a few metres of the seals. We propose that a management plan should be developed involving a study of the effect of boat approaches on seals utilising the Outer Harbor area followed by education coupled with enforcement.