A case study in successful management of a data-poor fishery using simple decision rules: the Queensland spanner crab fishery

Abstract

The Queensland spanner crab Ranina ranina is the target of a relatively data-poor, low-value fishery that has been managed for the last decade by using total allowable catches (TACs) in an individual transferable quota system. Despite the fact that this management system is usually applied to data-rich fisheries, it has been successfully used on this data-poor fishery. The key factor has been the use of harvest strategies that consisted only of simple decision rules that were appropriate given the size of the fishery and knowledge of the resource. These strategies were tested in a management strategy evaluation framework; however, it was not traditional in that (1) the operating model (or “true” resource to be managed) was not conditioned to data but rather was set to parameter ranges seen as appropriate for the resource and (2) the TAC was not set by using a stock assessment model, so the magnitude of the stock biomass was unknown. The important test was whether one could develop harvest strategies that were robust to this large uncertainty in knowledge by using only commercial catch rates. The management system had to be adaptive over time as more was learned about the biology of the species and how the harvest strategies affected the management of the fishery. This meant that the TAC was almost always set using the harvest strategies, but modifications to the decision rules were made on several occasions as more was learned about the fishery. The transparency and simplicity of the rules mean that the industry was empowered to make significant contributions to fine tuning the harvest strategies. As a result, the process does not rely solely on scientific advances but on the pooled knowledge of scientists, industry, and managers in a cooperative environment.