New Zealand sea lions Phocarctos hookeri and squid trawl fisheries: bycatch problems and management options

Abstract

The New Zealand (NZ) sea lion Phocarctos hookeri is one of the world's most rare and highly localized pinnipeds. NZ sea lions only breed on New Zealand's subantarctic islands, with 86% of breeding occurring on the Auckland Islands (50°S, 166°E). In 1995, the sea surrounding the Auck- land Islands out to 12 nautical miles (n miles) was declared a Marine Mammal Sanctuary, primarily to protect the breeding area of this species. Subsequently, in 2003, this area became a concurrent no- take Marine Reserve. Both protection measures ban commercial trawl fishing within this area. Trawl- ing is the predominant anthropogenic impact upon this species, both through direct (mortality as a result of bycatch) and potential indirect (resource competition) effects. However, despite this area- based protection and the fisheries management measures in the surrounding waters, the species, which numbers less than 12 000 ind., has shown a 30% decline in pup production over the last 8 yr. In this paper, I review the biology, foraging ecology and management of NZ sea lions in relation to the subantarctic arrow squid Nototodarus sloanii fishery to explore alternative management options within the framework of current legalisation in New Zealand. Management options need to afford better protection for this declining species, while still allowing profitable commercial fisheries operations for arrow squid in New Zealand waters.