UW Aquatic & Fishery Sciences Quantitative Seminar

André Punt

UW School of Aquatic and Fishery Sciences

Incorporating economics into reference points and control rules: An Australian Example

Abstract

The Australian Northern Prawn fishery (NPF) is one of the few that has adopted a dynamic version of a ‘maximum economic yield’ (MEY) target, and on this
basis the fishery is undergoing a process of substantial stock rebuilding. This talk outlines the ‘real time’ bioeconomic model that is used to manage the NPF, through changes in effort units given by total (and tradable) gear length in the fishery, both in terms of the MEY target and the path to MEY. It combines the stock assessment exercise for two species of tiger prawns (brown and grooved tiger prawns) with a specification for discounted economic profits, where the harvest function in the profit equation is stock dependent. Results for the NPF show a substantial ‘stock effect’, indicating the importance of conserving fish stocks for profitability. MEY thus occurs at stock levels that are larger than stock at maximum sustainable yield, giving a ‘win-win’ for both industry (with added profitability at MEY) and the environment (larger fish stocks). Sensitivity results add to this effect by showing that changes in the MEY target are much more sensitive to changes in the price of prawns and the
cost of fuel, and far less so to the traditional effect of changes in the rate of discount.