2006/220 Spatial management of Southern Rocklobster fisheries to improve yield, value and sustainability

By Caleb Gardner

This project investigated alternatives to the existing management rules. These rules have a history of providing for sustainable harvests but do not optimize economic yield from the available stock of southern rock lobster (Jasus edwardsii). One of the causes is that there is a mismatch between the scale of management of southern rock lobster across its Australian distribution and the scale of variation in biological traits of lobsters. Various forms of spatial management were considered within the project including regional size limits, incentives to draw effort into deeper water and translocating lobsters between regions. This idea of translocating lobsters between areas arose because lobsters could be caught in abundance in deep water and it was anticipated that their growth and quality would improve if they were shifted to shallow water. In effect, this was a form of sea-ranching where stock was shifted to better quality habitat.

Three approaches to managing a fishery with large-scale geographic variation were evaluated with all appearing to provide opportunity for sustainable increase in the value of harvests. Regional size limits better suited to local growth rates could increase yield, especially in areas that are growth under fished. The use of additional catch as an incentive to drag a portion of the catch into deep water was implemented with some success although record low recruitment into the fishery led to a hiatus in this initiative after two years. Of the options examined, greatest gains appear possible through the translocation of lower yield and value lobsters from deep water to shallow water as evaluated through a large-scale pilot experiment.