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2 December 2015 Increasing abundance of pups of the long-nosed fur seal (Arctocephalus forsteri) on Kangaroo Island, South Australia, over 26 breeding seasons to 2013–14
Peter D. Shaughnessy, Simon D. Goldsworthy
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Abstract

Context. Long-nosed (or New Zealand) fur seals breed on the southern coast of Australia, in New Zealand and on its subantarctic islands. They are recovering from over-harvesting that occurred in the early nineteenth century.

Aims. We estimated the rate of increase of the population at two colonies on Kangaroo Island, South Australia: Cape Gantheaume and Cape du Couedic.

Methods. From 1988–89 to 2013–14, pup abundance was estimated using a mark–resight procedure with multiple resights in large aggregations of pups and by direct counting in small aggregations.

Key results. At Cape Gantheaume, pup numbers increased by a factor of 10.7 from 457 to 5333 over 26 breeding seasons and the exponential rate of increase averaged 10.0% per annum (p.a.). Between 1988–89 and 1997–98, the population increased at 17.3% p.a., after which the increase was 7.2% p.a. At Cape du Couedic, pup numbers increased by a factor of 12.8 from 295 to 4070 over 21 breeding seasons at 11.4% p.a. Between 1988–89 and 1997–98, the increase averaged 14.2% p.a., after which it was 9.6% p.a. These increases have been accompanied by expansion in sub-colonies that existed in January 1989 and establishment of several new sub-colonies. Increases are likely to continue on Kangaroo Island.

Conclusions. There are few examples of increasing population levels for Australian native mammals and this is one of the best documented. It demonstrates that fur seal populations can recover from uncontrolled harvesting provided breeding habitat ashore is protected.

Implications. Fur seals interfere with fishers, disturb farmed tuna in aquaculture pens, and prey on little penguins.

© CSIRO 2015
Peter D. Shaughnessy and Simon D. Goldsworthy "Increasing abundance of pups of the long-nosed fur seal (Arctocephalus forsteri) on Kangaroo Island, South Australia, over 26 breeding seasons to 2013–14," Wildlife Research 42(8), 619-632, (2 December 2015). https://doi.org/10.1071/WR14209
Received: 13 October 2014; Accepted: 1 September 2015; Published: 2 December 2015
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