The South Australian lobster fishery management model

Modelling the rock lobster (Jasus edwardsii) fishery in South Australia was the focus of a three-year data gathering program. In collaboration with fishers, a tool for assisting in the sustainable management of the resource was developed. The goal was to test management policies to allow increases in reproductive output while enhancing economic yield. The model's user interface was developed to an ease of use comparable to commercial software for use by fishers in comanagement of the resource. This paper describes the modelling framework, user interface, and results for management strategies under consideration. The framework is comprised of five principle submodels: catch, effort, growth, economics, and population reproduction, with the lobster population divided into 8 mm length classes by sex and spatial cell. The mortality of lobsters occurs by commercial harvest, natural mortality, incidental release mortality, predation inside pots before retrieval, illegal harvesting, and recreational catch. Five categories of management control scenario were simulated: catch quota, effort regulation (as total pot retrievals), size regulations (allowing minimum, maximum, and mid-range slice length protection), and seasonal and area closures. Model outputs imply that size strategies have limited potential compared with effort limitations and quota.