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Title:

Understanding environmental and fisheries factors causing fluctuations in mud crab and blue swimmer crab fisheries in northern Australia to inform harvest strategies

Project Number:

2017-047

Organisation:

Department of Agriculture and Fisheries EcoScience Precinct

Principal Investigator:

Julie B. Robins

Project Status:

Current

FRDC Expenditure:

$161,433.33

Program(s):

Environment, Industry

Need

The work is needed to: (i) critically review the available literature on environmental factors influencing crab fisheries; (ii) update analytical relationships between catch and environmental factors to include the extreme climate events experienced in the past 10 years in the GoC, and for a broader range of environmental factors than previously considered; (iii) expand jurisdictional stock modelling to a more biologically appropriate scale and support cross-jurisdictional collaboration; (iv) test the ability of model results to inform management of the relative importance of fishing pressure compared to environmental factors; (v) develop reference point concepts suitable for adaptive harvest strategies for crab fisheries in northern Australia. The project will provide information at a broad spatial scale (i.e., GoC) for crab species with different life histories and potentially different responses to environmental factors. It will compare the declining catches of mud crabs with the anecdotally reported increasing catches of blue swimmer crabs in the GoC. Recent increases in blue swimmer crab catches in the GoC needs to be investigated to clarify which species are present and to assess their vulnerability to fishing. The adaptation of an existing crab population model will be a case study that potentially could be applied to the Queensland east coast and other crustacean species. The current work will assist in determining whether the NT GoC mud crab fishery warrants management intervention as a consequence of environmental factors. The recent closure of blue swimmer crab fisheries in WA highlights the potential of environmental factors to seriously impact a stock to the point where fishing needs to be removed (Johnston et al 2011).

Objectives

1. Evaluate the role of a broad range of environmental drivers on catch variation in Northern Territory and Queensland crab fisheries of the Gulf of Carpentaria.

2. Explore the relative importance of fishing pressure compared to environmentally driven variability using a population model of the GoC mud crab fishery.

3. Provide advice to support the development of harvest strategies appropriate for crab fisheries in northern Australia.