Fisheries biology of the giant crab (stage 2)
Deakin University Geelong Waterfront Campus
The development of this proposal is strongly supported by the Australian Southern Rock Lobster Council who want sustainable development. The council realises the need for research, monitoring and extension, so that future management issues inherited with the OCS transition can be addressed. Issues such as limitation of access, pot numbers, sustainable yield, compliance with regulations and optimisation of product value, will all require a firm knowledge base for consideration. The major problem is to establish the intermoult period so that growth rates can be established. In terms of population structure we have a reasonable picture so far, however the price differential for the crabs indicates product value could be optimised by selective harvest of a range of smaller sizes. This option could not be initiated without real time data on population structure. Given the current history of depletion in some areas of the fishery, the consideration of this option in the absence of such information, would lead to overfishing and mismanagement. The crabs wide geographic distribution (straddling 11 management areas), the changeover in jurisdictional responsiblity, its status as a developing fishery and its $11 million per annum value are justification for a continued effort on the species. It would be foolish to squander an Australia-wide effort involving industry, scientists and government, at the time when states are working to formalise managment of the fishery; to discontinue research when information is most needed. Managers will not have the advice they need if the resource is handled peicemeal by the new array of jurisdictions, however this project offers an existing cost effective network and an overview that will provide most of the information needed to deal with the fundamental issues. The future of the Giant Crab fishery is a national resource development issue.
1. To determine intermoult period and complete the essential information needed to establish growth rates.
2. To determine the continuing effects of fishing on population structures an implications for sustainability.
3. To determine the effects on yield per recruit of moult timing and therefore the catch available to the commercial fishery.
4. To model the fishery using two methods a)an individual based model b)a spatial dynamic fishery population model patterned after the rock lobster model of SA.
5. To assess moult timing and the development of a condition index as a layman's guide for selection of premoult crabs from the wild harvest for holding in sea cages for a single moult to value add.
6. To improve genetic analysis of giant crab populations using DNA rather than protein based techniques to provide information of high resolution.
7. To continue to document the development of the fishery and its realtionship with the southern rock lobster fishery.
8. To oportunistically conduct preliminary modelling of the spiny crab (hypothallassis amata) in regard to size, sex, reproductive state and shell state, coincident with giant crab catch sampling in southern WA.
9. To oportunistically build an experiment with seafloor collectors to determine effectiveness of catching giant crab larvae.
Principal Investigator: A. Levings, B. D. Mitchell, R McGarvey, J Mathews, L Laurenson, C Austin, T Heeron, N. Murphy, A. Miller, M Rowsell and P. Jones