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.