New Zealand sea lion predation on New Zealand fur seals

Abstract

Several sea lion species are known to occasionally hunt fur seals for food, but there have been few reports of New Zealand (Hooker's) sea lions {Phocarctos hookeri) hunting and eating New Zealand fur seals (Arctocephalus forsteri) We describe the first reported incidence of P. hookeri eating A. forsteri pups in mainland New Zealand, and present evidence suggesting that it was active predation rather than scavenging. In late April, early May, and early September 1997 we found three sea lion regurgitations containing the remains of fur seal pups on Otago Peninsula, New Zealand. One contained three plastic tags formerly placed on three different female fur seal pups from a nearby breeding colony. When ingested at least two of the three identifiable pups fell within the lower condition quartile calculated from pups at their natal colony. The incidence of such predation may increase with increasing densities of both fur seals and sea lions in Otago, but the impact on the trends in fur seal populations is, and should remain, low.