Modelling effort levels in a sequential fishery

Abstract

Developing bioeconomic models of sequential fisheries is complicated when the two (or more) fisheries overlap temporally. In such cases, each fishery will be affected by the other, so both cannot be properly modelled as separate activities. This has recently become an issue for the Northern Prawn Fishery, in which bioeconomic modelling is used to set management limits. Modelling has focused on the tiger prawn component of the fishery, which mostly occurs in the second half of the year. However, successful management leading to stock recovery has resulted in this fishery nowoverlapping temporally with the banana prawn fishery, which occurs in the first half of the year. Ideally, an integrated model covering the whole year would be developed, but this is not practical for a numberof reasons. In this study, wemodel the factors driving the level of fishing effort in the banana prawn fishery, which affects, and is affected by, the tiger prawn fishery. As expected, banana prawn fishing effort is driven largely by stock size, fleet size, catch rates, prices, and fuel costs. Effort increases with fleet size, but at a decreasing rate. Further, we find evidence that opportunity cost, namely the ability to fish in the tiger prawn fishery and the price of tiger prawns, also affects the level of effort in the banana prawn fishery.