Project number: 1998-152
Project Status:
Completed
Budget expenditure: $114,594.93
Principal Investigator: Stephen J. Newman
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 21 Jun 1998 - 21 Jul 2004
Contact:
FRDC

Need

Trawling in waters west of the 200m isobath is managed by AFMA as part of the NWSTF. AFMA's draft Management Plan for the NWSTF does not encompass fishing for finfish, and this omission has been the main impediment to implementing the Plan to date. In order for the Plan to fully cover all fishery resources within the NWSTF area, knowledge of the distribution of demersal scalefish and their relative abundance is urgently needed.

In the waters east of 120oE, a fishery already exists which covers the slope for line and trap fishing, though no formal discussions have been held with the Commonwealth regarding trawling for the same fish resource in that area. Clearly the jurisdictional arrangements need to be reviewed. The capability of the State-managed and the Commonwealth-managed fishing methods to utilise the resources at different depths form part of the basis for this review.

There is a need for information on the type of resource available to fishers, the relative abundance of those species which have either commercial potential or current market acceptance in the Indo-Pacific and the relative catchability of each of the fishing methods (fish trawl vs. fish trap vs. line). Furthermore, there is a need for biological information (eg. longevity, natural mortality, reproductive biology) about the key species available to fishers in order to begin to understand the population dynamics of these species and hence to assess their vulnerability to fishing pressure. The information that will be provided by this project will form the basis for reviewing the current OCS arrangements between the State and the Commonwealth and will assist in developing management plans for the sustainable exploitation of the demersal fish resources of the North West slope.

Objectives

1. To determine the species distributions and composition of demersal scalefish resources on the NW slope and to examine industry collected catch and effort data to determine an index of relative abundance.
2. To assess the viability of exploiting the demersal scalefish resource of the North-West Slope using (a) fish trawls, traps and lines in the western zone (west of 120 degrees longitude) and
(b) traps and lines in the eastern zone (east of 120 degrees longitude).
3. To gather biological information on the major species (eg. to investigate longevity, natural mortality and aspects of their reproductive biology).

Final report

ISBN: 1 877098 23 X
Author: Stephen Newman
Final Report • 2003-08-29 • 1.87 MB
1998-152-DLD.pdf

Summary

The nature and extent of demersal finfish resources in deep slope waters (>200m) off the northwest coast of Western Australia are poorly understood.  Existing fish trawl, trap and line fishing effort is concentrated in shallower waters (<200m), while trawling in deep slope waters (>200m) exclusively targets crustaceans.

Despite significant initial levels of interest in this project, poor commercial catches contributed to fishers returning to grounds in shallower waters on the shelf.  As a consequence of the lack of significant commercial catches in the deep slope region there was a very low level of industry participation in the project.  To date there is little evidence to indicate the existence or otherwise of significant demersal fish resources in the deep slope region.

A number of high value species were landed from the survey and include; lenko snapper (Dentex tumifrons), ruby snapper (Etelis carbunculus), flame snapper (Etelis coruscans), eight bar cod/grouper (Epinephelus octofasciatus) and Tang snapper (Lipocheilus carnolabrum).

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