What is an appropriate spatial scale for ecosystem based fishery management of kōura, spiny lobster Jasus edwardsii, in the Hauraki Gulf Marine Park, Aotearoa New Zealand?

Abstract

Ecosystem based fishery management (EBFM) remains an aspiration in Aotearoa New Zealand where single species fisheries assessments at large quota management area (QMA) spatial scales are standard. This review of the available information for the spiny lobster or kōura (Jasus edwardsii) in the Hauraki Gulf Marine Park (part of the CRA2 QMA) indicates that the present large scale fisheries assessment violates the modelling assumption of a unit stock because of smaller scale spatial patterns of puerulus settlement, juvenile and adult movement, abundance, ecological interactions, and fishing. While EBFM at the reef scale would be consistent with the limited movement of juvenile and adult kōura among adjacent reefs, high information requirements at this small scale demand a stepped transition from the QMA scale. Assessments of the CRA2 kōura stock based on six subregions would allow the identification of routes for population rebuilding in each sub-region and the development of EBFM of kōura at scales more relevant to its biology, ecology and fisheries as well as the communities with a stake in its sustainability. Management at these scales will require using existing fine-scale data where it exists and consideration of new ways to collect the required data at a suitable spatial scale to help fill the information gaps.