Summer foraging areas for lactating New Zealand sea lions Phocarctos hookeri

Abstract

The overlap between marine mammal species and fisheries is a source of ongoing conflict and concern. This study used satellite telemetry to examine the foraging patterns of 26 lactating female New Zealand sea lions Phocarctos hookeri from the Sandy Bay colony, Enderby Island, Auckland Islands (50°50'S, 166°28'E), over 4 consecutive austral summers from 2001 to 2004. Animals were fitted with satellite-linked platform transmitting terminals (PTTs), which yielded 9200 filtered foraging locations at sea. Trips lasted a mean of 66.2 h (SE = 4.2, n = 183). Mean return travel distance per trip was 423 km (SE = 43.9, max. = 1087, n = 183). There was a high level of variation in individual foraging parameters, and evidence of individual preference and partitioning in foraging locations among individuals within the colony. New Zealand sea lions exhibited preferential use of the continental shelf and its edge and this pattern was consistent among years. Female foraging locations overlap temporally and spatially with the operation of the sub-Antarctic arrow squid trawl fishery. Here we identify the key foraging areas for female New Zealand sea lions from Sandy Bay, show how these overlap with the operational areas of the squid fishery and discuss the importance of these findings to the management of New Zealand sea lions and the sub-Antarctic squid fishery. © Inter-Research 2005.