Project number: 2008-102
Project Status:
Completed
Budget expenditure: $73,181.68
Principal Investigator: Jeremy Prince
Organisation: Murdoch University
Project start/end date: 29 Nov 2009 - 29 Apr 2010
Contact:
FRDC

Need

Until recently management of prawns in the Joseph Bonaparte Gulf (JBG) has been a “byproduct” of measures designed for other NPF stocks. In recent years, the JBG has been fished with the two seasonal openings (April to June, August to November), however in 2007 this arrangement changed, and fishing has only been allowed August to November. The rationale of this change was to see if average size of prawns, and total value of the catch could be increased. However, no clear objectives, performance measures or monitoring system were established to evaluate whether this was achieved.

Little targeted research has been carried out on red-legged banana prawns (Penaeus indicus), the main JBG species. In recent years only rudimentary catch and effort, and commercial grading data have been collected. Even this has not been subject to systematic analysis. In these circumstances anecdotal accounts of recent trends can be argued to support five plausible explanations with differing management implications:
1. The late season has optimized value of production.
2. Value is being forfeited because the season is too late and peak annual biomass is being missed.
3. Value is being forfeited because poor weather late in the year and other fishing commitments prevent limit boats days in the JBG.
4. The late season intensifies fishing on the aggregated spawning biomass risking recruitment over-fishing.
5. Natural variability has produced lower catches than normal.

The NPF Industry Pty Ltd needs its discussion of management in the JBG, and other localized stocks, to be based on sound scientific data. The immediate need is to provide a scientific basis for discussions about the 2010 season, which will occur in late 2009. The medium term need is for NPF Industry Pty Ltd develop its capacity to conduct cost-effective data collection programs.

Objectives

1. Collect and review all existing data and research results for the JBG red-legged banana prawn stock.
2. Develop a preliminary assessment of the JBG red-legged banana prawn stock focusing on how yields, catch rates and production costs might be optimized in the medium and long term.
3. Conduct an initial sensitivity analysis using the preliminary assessment model to identify critical gaps in the knowledge needed to optimize red-legged banana prawn production in the JBG.
4. Identify data that would be most valuable for industry to collect
5. Present these analyses and findings to an industry meeting to develop a systematic approach to optimising the value of red-legged banana prawns from the JBG.

Final report

Author: Jeremy Prince
Final Report • 2017-09-29 • 2.65 MB
2008-102-DLD.pdf

Summary

To enhance its profitability, NPF Industry Pty Ltd needs to develop its capacity to gather key stock status data for each of its stocks so that simple bio-economic models can be developed and used to assess and potentially optimize the value of component NPF stocks. The NPF Industry Pty Ltd needs its discussion of management policy for localized stocks to be based on sound scientific data. This project started developing the capacity of NPF Industry Pty Ltd to support science based discussions of management by synthesizing the existing data for the red-leg banana prawn (Penaeus indicus) stock in the Joseph Bonaparte Gulf (JBG) and developing initial, simple bioeconomic models for the stock.

Related research

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