Environmental and fishing effects on the dynamic of brown tiger prawn (Penaeus esculentus) in Moreton Bay (Australia)

TL;DR

This study models the catch dynamics of brown tiger prawns in Moreton Bay, considering factors like fishing effort, power, and behavior changes, revealing how temperature influences prawn availability and fishery productivity.

Contribution

It introduces a delay difference model that integrates multiple factors affecting catchability, providing new insights into prawn fishery dynamics and the impact of environmental and operational variables.

Findings

Targeted catchability is twice non-targeted catchability.

Temperature significantly affects prawn behavior and availability.

Recent decline in fishing effort is discussed.

Abstract

This analysis of the variations of brown tiger prawn (Penaeus esculentus) catch in the Moreton Bay multispecies trawl fishery estimated catchability using a delay difference model. It integrated several factors responsible for variations in catchability: targeting of fishing effort, increasing fishing power and changing availability. An analysis of covariance was used to define fishing events targeted at brown tiger prawns. A general linear model estimated inter-annual variations of fishing power. Temperature induced changes in prawn behaviour played an important role in the dynamic of this fishery. Maximum likelihood estimates of targeted catchability ($3.92 \pm 0.40 \ 10^{-4}$ boat-days$^{-1}$) were twice as large as non-targeted catchability ($1.91 \pm 0.24 \ 10^{-4}$ boat-days$^{-1}$). The causes of recent decline in fishing effort in this fishery were discussed.