One of the complicating factors in trying to solve the mystery of why sea lion numbers are not increasing is their unique breeding cycle. Of the 35 pinniped (seal) species in the world, the Australian sea lion is the only type which does not have a strict, annual breeding cycle.
A female sea lion will give birth to a pup after an 18 month cycle, meaning that her pupping season occurs in alternate summers and winters, or in alternate springs and autumns.
While calling for more scientific study of Australian sea lions to try to maximise their breeding potential, Dr Shaughnessy has welcomed the steady growth of NZ fur seal numbers, especially in South Australia.
He says it is clear from his team's most recent mark-recapture (count) of NZ fur seals in the summer of 1998 that the species is recovering from its overharvesting by sealers in the last century and early 20th century.
"Each year we return to South Australia we find greater numbers and new colonies, some of them admittedly quite small, and we should all be thankful that these wonderful creatures are making a healthy comeback," says Dr Shaughnessy.
NZ fur seals are also found in Western Australia, off southern Tasmania and occasionally in New South Wales.
Dr Shaughnessy has carried out his research in conjunction with National Parks and Wildlife South Australia staff based at Kangaroo Island and Port Lincoln.
More information from:
Dr Peter Shaughnessy Phone: (02) 6242 1760
Principal Research Scientist
peter.shaughnessy@dwe.csiro.au
David
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Contact: Mr David Salt
david.salt@dwe.csiro.au
61-2-6242-1645
CSIRO Australia
18-Mar-1998