2 results

Relative efficiency of fishing gears and investigation of resource availability in tropical demersal scalefish fisheries (NDSF)

Project number: 2006-031
Project Status:
Completed
Budget expenditure: $581,744.00
Principal Investigator: Stephen J. Newman
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 29 Sep 2006 - 29 Nov 2010
Contact:
FRDC

Need

There is an urgent need for fishery independent data to improve and calibrate abundance measures of tropical demersal finfish species derived from commercial catch data that underpins quota setting processes. More specifically, species specific catchability measures are required for the main target species in the NDSF and other similar fisheries, to determine how the landed catch of each species relates to the overall biomass of the stock in the fishery region. At present the limited understanding of the catchability relationship is leading to the management need to set conservative risk-averse effort quota levels which are allegedly constraining the development of this fishery. This project will use ‘baited remote underwater video’ (BRUVs) and research vessel trawl surveys to directly assess the size composition and abundance of relevant fish species in trap and line fishing areas to generate the necessary data on catchability for each fishing method. The trawl survey derived size composition data for target species will also be used to meet the need for unbiased population samples in the stock assessment models, and will be designed to be replicated in the future (at an appropriate temporal scale). The successful completion of this project will meet the requirement for more precision in the stock size estimates and therefore meet industry’s requirement for an optimal and possibly less constraining approach to effort quota setting in the NDSF and similar fisheries.

Objectives

1. Determine the relative catching efficiency of trap and line fishing gears in the NDSF
2. Determine the availability and spatial distribution of fish resources harvested by the NDSF
3. Develop a long-term monitoring program for the NDSF that incorporates fishery independent monitoring

Biological parameters for managing the fisheries for blue and king threadfin salmons, estuary rockcod, malabar grouper and mangrove jack in north-western Australia

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

Need

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.

Objectives

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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