Reference point management and the role of catch-per-unit effort in prawn and scallop fisheries
Department of Agriculture and Fisheries EcoScience Precinct
Michael F. O'Neill
Fishery Management Plans are currently being developed for all major fisheries in Queensland. In the next few years, these plans will become the legal framework within which management practices are applied. Limit and target reference points have been developed and put forward as key assessment and management tools in all of these plans. Methods used to estimate the reference points have generally been ad hoc and based on un-standardised catch and effort data. Clearly, there is a strong need to test these reference points. In the Queensland Trawl Fishery Management Plan (east coast - Moreton Bay) 1998-2005, the limit reference points are based on a comparison of the average logbook catch-per-unit-effort from 1988-96 with the relevent year's catch-per-unit-effort. At present, this comparison of CPUEs takes no account of changes in effective effort. However, effective fishing effort continually increases, even though the number of licence holders or total number of days fished each year may remain constant. This continual “effort creep” is characteristic of trawl fleets and is due to fishers adopting technological improvements in fishing practices, such as GPS and plotters. A recent study of the northern prawn fishery indicates that when GPS and plotters are used concurrently, relative fishing power increases by 7% over boats without such equipment (Robins et. al. in press). We propose to standardise the effort of the trawl fleet, which is capital intensive and would therefore be most affected by technology advances. Two major trawl fleets operate within the Queensland region, the Torres Strait trawl and the Queensland East Coast trawl licensed fleet. In terms of value, the most important species captured by these vessels are tiger prawns, eastern king prawns and saucer scallops. AFMA and the Torres Strait Scientific Advisory Committee see a priority need that catch rate analysis of the Torres Strait tiger prawn fishery be undertaken. The prawn Working Group for Torres Strait has discussed this issue of possible changes in effective effort and the managers are of the opinion that this issue needs to be investigated. The small size of the fleet will simplify analysis compared to analysing the full Queensland tiger prawn fishery. In summary, therefore, effective reference points must be clearly defined and relate to a management system that uses a catch-per-unit effort series adjusted for changes in fishing power.
1. Produce an in-depth description and catalogue of the gear and technological improvements of a representative sample for the a) Torres Strait tiger prawn, b) Queensland eastern king prawn and c) south-east Queensland saucer scallop fisheries for the period 1970 to present.
2. Establish a standardised catch-per-unit effort series of the above fisheries.
3. Compare present Management Plan reference points with the standardised and unstandardised catch-per-unit effort series.
4. Investigate and establish robust reference points and response mechanisms through simulation modelling.
5. Disseminate results to TrawlMAC, the QFMA trawl fishery manager and fishers.
Principal Investigator: Michael F. O`Neill, Anthony J. Courtney, Norm M. Good, Clive T. Turnbull, Kate M. Yeomans, Jonathan Staunton-Smith and Celeste Shootingstar