New Zealand Journal of Ecology (2009) 33(2): 97- 105

Distribution, pup production and mortality of New Zealand sea lion Phocarctos hookeri on Campbell Island / Motu Ihupuku, 2008

Research Article
Andy Maloney 1
B. Louise Chilvers 2*
Marie Haley 3
Chris G. Muller 4
Wendi Roe 5
Igor Debski 2
  1. 11 Koromiko Rd, Highbury, Wellington 6012, New Zealand
  2. Aquatic & Threats Unit, Department of Conservation, PO Box 10-420, Wellington 6011, New Zealand
  3. PO Box 26, Akaroa 7542, New Zealand
  4. PO Box 51-287, Pakuranga, Auckland, New Zealand
  5. New Zealand Wildlife Health Centre, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand
*  Corresponding author

Surveys were undertaken at Campbell Island / Motu Ihupuku during January and February 2008, to determine the distribution and pup production of New Zealand sea lions (NZ sea lion; Phocarctos hookeri). In addition, necropsies were performed at the main breeding site of Davis Point to determine the principal causes of early mortality for NZ sea lion pups. In total, 397 pups were tagged and 186 untagged pups were found dead, giving a minimum pup production of 583 pups and a one month of age mortality estimate of 40%. This represents a higher pup production than previous estimates from Campbell Island (although survey techniques are not comparable), and equates to 21% of the total pup production for NZ sea lions in the 2007/08 season. Early pup mortality was high (40%) at Campbell Island, with trauma, starvation, and drowning in rock pools and peat mires the major causes of death. Pups were concentrated in two colonial breeding sites: Davis Point on the north shore of Perseverance Harbour (76%) and a newly recorded breeding site (Paradise Point) on the southern shore of Perseverance Harbour (21%). Non-colonial breeding or single pups occurred around the southern parts of the island from sea level to 400 m; however, these only contributed 3% of the known pup production.