Historical and modern distribution and abundance of the New Zealand sea lion Phocarctos hookeri

This paper describes both the modern and the pristine distribution, breeding range, and relative abundance of the New Zealand sea lion (Phocarctos hookeri). Archaeological data and historical references were used to determine the pristine status of the sea lion, and its present status was determined from recent scientific studies and observations. The sea lion had a substantially more widespread distribution before the arrival of humans in New Zealand than it does today. The species used to range along the whole length of the coast, from the north of the North Island through to Stewart Island and the subantarctic islands. Although we have no direct estimate of pristine abundance, the present population size is clearly reduced. Subsistence and commercial killing of sea lions is the most likely cause of historical changes in distribution and abundance. Their pristine breeding range extended at least as far north as Nelson and may have extended to the North Island. The present breeding range is restricted to the Auckland Islands and Campbell Island. Within the last 10 years a few individuals have started to breed on mainland New Zealand and Stewart Island, which may reflect a slow recolonisation of earlier breeding grounds. Pup production at Sandy Bay, Enderby Island, has been stable for at least the last three decades, and no major changes in pup production at Dundas Island and Figure of Eight Island are apparent.