Colony growth and pup condition of the New Zealand fur seal (Arctocephalus forsteri) on the Kaikoura coastline compared with other east coast colonies
L. J. Boren A B , C. G. Muller A and N. J. Gemmell AA School of Biological Sciences, University of Canterbury, Christchurch, New Zealand.
B Corresponding author. Present address: New Zealand Department of Conservation, Marine Conservation Unit, 186 Bridge Street, Nelson, New Zealand. Email: lboren@doc.govt.nz
Wildlife Research 33(6) 497-505 https://doi.org/10.1071/WR05092
Submitted: 19 October 2005 Accepted: 11 July 2006 Published: 4 October 2006
Abstract
Abstract. Since its near extermination by sealing, the New Zealand fur seal (Arctocephalus forsteri) has been recolonising areas of its former range throughout New Zealand and Australia. This study examined fur seal population growth over four breeding seasons spanning 2002–05 at the Ohau Point and Lynch’s Reef colonies in Kaikoura and the Horseshoe Bay and Te Oka Bay colonies on Banks Peninsula, on the east coast of New Zealand. Estimates of pup numbers were made using mark–recapture techniques and condition indices were used to assess the body condition of pups in each colony. We found that the Ohau Point and Te Oka Bay colonies are growing exponentially (32% and 47% per annum respectively), reaching nearly 600 pups at Ohau Point and 300 pups at Te Oka Bay, whereas Horseshoe Bay appears stable. Pups born at Ohau Point are consistently heavier and in better condition than their Banks Peninsula counterparts despite the faster rate of growth observed at Te Oka Bay. An El Niño event in 2003 coincided with a drop in mass and condition at the Banks Peninsula colonies, but not at the Kaikoura colony. This discrepancy between colonies in response to environmental conditions suggests that colony-specific variables at Kaikoura may provide more favourable conditions for rearing pups than on Banks Peninsula.
Acknowledgments
The authors thank the Department of Conservation for logistical assistance with this project, and the Banks Peninsula land owners, Nicky Hutchison and Gerald Harper, for access to the Horseshoe Bay and Te Oka Bay seal colonies. We also acknowledge the numerous field assistants who helped on field trips, as well as Melinda Fowler (Sonoma State University), Abigail Caudron, Sacha Dowell, Bruce Robertson and Jim Briskie (University of Canterbury), Kerry Barton (Landcare Research, Nelson), Robert Harcourt (Macquarie University, Sydney) and Simon Goldsworthy (PIRSA-SARDI, South Australia) for their input on earlier versions of the manuscript. Two anonymous reviewers and Dr Camilla Myers (CSIRO) also provided invaluable feedback on the manuscript. Thanks go to Corey Bradshaw (Charles Darwin University) and Mike Morrissey (Department of Conservation, Kaikoura) for access to historical data. Financial assistance was provided by the Minority International Research Training Program, Canterbury University Doctoral Scholarship and the Whale and Dolphin Adoption project. Research was carried out under Department of Conservation Permit: Per/10/2002/01.
Arnould, J. , and Warneke, R. (2002). Growth and condition in Australian fur seals (Arctocephalus pusillus doriferus) (Carnivora: Pinnipedia). Australian Journal of Zoology 50, 53–66.
| Crossref | GoogleScholarGoogle Scholar |
Benoit-Bird, K. , Würsig, B. , and McFadden, C. (2004). Dusky dolphin (Lagenorhynchus obscurus) foraging in two different habitats: active acoustic detection of dolphins and their prey. Marine Mammal Science 20, 215–231.
| Crossref | GoogleScholarGoogle Scholar |
Boren, L. J. , Gemmell, N. J. , and Barton, K. J. (2002). Tourist disturbance on New Zealand fur seals, Arctocephalus forsteri. Australian Mammalogy 24, 85–96.
Carey, P. W. (1998). New Zealand fur seals (Arctocephalus forsteri) at the Snares Islands: a stabilised population? New Zealand Journal of Marine and Freshwater Research 32, 113–118.
Chilvers, B. , Wilson, K. , and Hickling, G. (1995). Suckling behaviours and growth rates of New Zealand fur seal, Arctocephalus forsteri, at Cape Foulwind, New Zealand. New Zealand Journal of Zoology 22, 263–270.
Goring, D. G. , and Henry, R. F. (1998). Short period (1–4 h) sea level fluctuations on the Canterbury coast, New Zealand. New Zealand Journal of Marine and Freshwater Research 32, 119–134.
Harcourt, R. (2001). Advances in New Zealand mammalogy 1990–2000: pinnipeds. Journal of the Royal Society of New Zealand 31, 135–160.
Pitcher, K. W. (1986). Variation in blubber thickness of harbor seals in southern Alaska. Journal of Wildlife Management 50, 463–466.
Shaugnessy, P. , Gales, N. , Dennis, T. , and Goldsworthy, S. (1994). Distribution and abundance of New Zealand fur seals, Arctocephalus forsteri, in South Australia and Western Australia. Wildlife Research 21, 667–695.
| Crossref | GoogleScholarGoogle Scholar |
Taylor, R. , Barton, K. , Wilson, P. , Thomas, B. , and Karl, B. (1995). Population status and breeding of New Zealand fur seals (Arctocephalus forsteri) in the Nelson–northern Marlborough region 1991–94. New Zealand Journal of Marine and Freshwater Research 29, 223–234.
Troy, S. , Mattlin, R. , Shaughnessy, P. , and Davie, P. (1999). Morphology, age and survival of adult male New Zealand fur seals, Arctocephalus forsteri, in South Australia. Wildlife Research 26, 21–34.
| Crossref | GoogleScholarGoogle Scholar |
Wynen, L. , Goldsworthy, S. , Guinet, C. , Bester, M. , Boyd, I. , Gjertz, I. , Hofmeyr, G. , White, R. , and Slade, R. (2000). Postsealing genetic variation and population structure of two species of fur seal (Arctocephalus gazella and A. tropicalis). Molecular Ecology 9, 299–314.
| Crossref | GoogleScholarGoogle Scholar | PubMed |