Project number: 2002-003
Project Status:
Budget expenditure: $336,038.11
Principal Investigator: Ian Potter
Organisation: Murdoch University
Project start/end date: 29 Jun 2002 - 15 May 2006


There is an urgent need to obtain detailed information on crucial aspects of the biology of the above five species so that appropriate management plans can be developed for conserving these species. The importance of conserving these species is demonstrated by the following:

1. Each of the five species makes a very important contribution to the nearshore and boat-based recreational fishery in the region, with the threadfin salmons being the species that are the most sought-after and caught by shore-based recreational fishers;

2. The threadfin salmons are by far the most important component of the catches of the KGBMF;

3. The recreational, commercial and aboriginal fisheries and the charter boat and “fishing safari” operations collectively generate income, jobs and tourism, that are of vital importance to the economies of the small and isolated communities of the region;

4. These species represent the major food source for local aboriginal communities and the threadfin salmons, in particular, are of great cultural significance for these communities.

The development of effective management plans is critical for preventing an escalation of the conflict that exists amongst recreational, commercial, charter and aboriginal fishers. The need for sound biological information to develop those plans has been identified by the members of each of those fishing sectors and by the support of Dr R. Lenanton (Supervising Finfish Scientist, Department of Fisheries WA) and Mr Frank Prokop (Executive Director, RecFishWest) in developing this application.


1. The main objective is to produce the biological data for the blue and king threadfin salmons, estuary rockcod, malabar grouper and mangrove jack in the Pilbara/Kimberley upon which effective management plans may be developed. Specifically, this will involve determining the following:
2. Size and age compositions, sex ratios, growth rates and the sizes and ages at which the first four species change sex.
3. Sizes and ages at which females and males reach maturity, the duration and location of spawning and whether multiple spawning occurs within a breeding season.
4. Batch fecundity and its relationship to body size.
5. Size compositions of fish caught by recreational, commercial, aboriginal and charter fishers.
6. A yield and spawning biomass per recruit assessment and an evaluation of the effectiveness of different legal minimum and maximum sizes.

Final report

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