Effects of Trawling Subprogram: bycatch weight, composition and preliminary estimates of the impact of bycatch reduction devices in Queensland's trawl fishery
Department of Agriculture and Fisheries (QLD)
Tony J. Courtney
There is a need to assess how bycatch reduction devices (BRDs) are likely to affect the weight and composition of bycatch in the Queensland east coast trawl fishery (QECTF). Mandatory use of the devices has been recently implemented in some sectors and further measures are proposed. There is a need to estimate and compare the weight and composition of bycatch with- and without-BRDs to assess recent and ongoing bycatch reduction initiatives that have been legislated in the Queensland Trawl Fishery Management Plan. Deploying observers or researchers appears to be the only robust approach for undertaking these comparisons. Current estimates of the weight and composition of bycatch from the fishery operating without-BRDs are unknown for most sectors of the QECTF. These will have to be derived in order to facilitate any comparisons with estimates obtained when the fishery is operating with-BRDs. There is also a need for the QECTF to consider the Criteria for Assessing Sustainability of Commercial Fisheries under the Wildlife Protection Act 1984 and the project makes some headway towards addressing these criteria.
1. Describe the bycatch species composition and catch rates under standard trawl net (pre TED and pre BRD) conditions in Queensland's major trawl sectors (eastern king prawn, scallop and tiger/endeavour prawn sectors).
2. Describe the bycatch species composition and catch rates when nets have TEDs and BRDs installed (post TED and post BRD) in Queensland's major trawl sectors.
3. Test and quantify the impact of different combinations of TEDs and BRDs on bycatch and target species against standard nets under controlled experimental conditions using chartered commercial trawlers in the eastern king prawn, scallop and tiger/endeavour prawn sectors.
4. Review the known biology and distribution of all recently approved "permitted fish" species associated with the trawl fishery.
5. Quantify key population parameter estimates, including growth rates, size at maturity, distribution and landings, for all recently approved "permitted fish" species.
6. Apply power analysis to determine how many trawl samples are needed to detect various levels of change in individual bycatch species catch rates.
7. Provide advice on the guidelines and definitions of BRDs and TEDs so that the Boating and Fisheries Patrol can confidently enforce the regulations.
Principal Investigator: A. J. Courtney, J. A. Haddy, M. J. Campbell, D. P. Roy, M. L. Tonks, S. W. Gaddes, K. E. Chilcott, M. F. O`Neill, I. W. Brown, M. McLennan, J. E. Jebreen, C. van der Geest, C. Rose, S. Kistle, C. T. Turnbull, P. M. Kyne, M. B. Bennett and J. Taylor