New Zealand Journal of Marine and Freshwater Research abstracts
Distribution, abundance and growth of New Zealand sea lion Phocarctos
hookeri pups on Campbell Island
Simon Childerhouse 1
Nadine Gibbs 1
Gus McAlister 2
Shaun McConkey 3
Helen McConnell 1,3
Nathan McNally 1
David Sutherland 4
1Department of Conservation
P.O. Box 10420
Wellington, New Zealand
25 Blue Cliffs Beach Rd
RD 1
Tuatapere, New Zealand
3New Zealand Sea Lion Trust
76 Elm Row
Dunedin, New Zealand
479/4 Alice St
Invercargill, New Zealand
Abstract Nine weeks field work was completed during two
trips in January/February and March/April 2003 to investigate the distribution
and abundance of New Zealand sea lion Phocarctos hookeri pups at Campbell
Island. A total of 161 pups were tagged and a further 138 dead pups were found.
A closed mark-recapture model was used to estimate the total number of live
pups (e.g., tagged plus untagged pups) at Campbell Island in April as 247
(SE = 28, 95% CI 198-308). Pup production at Campbell Island is estimated
at 385, which comprises 13% of the total pup production for the species in
the 2003 season. This is the first robust estimate of pup production for New
Zealand sea lions at Campbell Island. The figure of 385 pups is considerably
higher than any of the previous estimates reported from Campbell Island. The
high level of pup mortality (36%) at Campbell Island for approximately the
first 2 months after birth is higher than the 17% reported for the Auckland
Islands for approximately the same period in 2003, but is similar to unusually
high levels of mortality (20-30%) reported at the Auckland Islands in recent
years. It was not possible to determine the cause of death of the 138 dead
pups owing to scavenging and decomposition. Pups were found over the whole
Island, with the exception of its northern end. Male pups were significantly
heavier and faster growing than female pups over the same period.
Keywords Phocarctos hookeri; subantarctic; sea
lion; New Zealand; Campbell Island; survey; breeding; distribution; abundance;
pup growth
M04151; Online publication date 17 June 2005 Received 2 November 2004;
Accepted 28 January 2005
New Zealand Journal of Marine and Freshwater Research, 2005, Vol. 39:
889-898
0028-8330/05/3904-0889 © The Royal Society of New Zealand 2005
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