This project provides the opportunity to develop a new mud crab aquaculture industry for tropical and sub- tropical Australia. It will provide the crablets needed by pioneering farmers to run the first grow-out trials.
Industry has identified the need to commercialise this technology, as can be seen by the involvement of Seafarm and McRobert Aquaculture Systems participation in this project.
Seafarm is determined to secure a reliable supply of crablets for its Queensland operation, following the initial success of the first crop of crablets recently grown and harvested from its ponds. The company has stated its intention to diversify into mud crabs, in addition to its core prawn farming business.
McRobert Aquaculture Systems is aiming to get involved with the supply of crablets to both Australian and international markets, using its new tank system. It is also keen to ensure its new tank system is fully field tested for mud crab larval culture, so that it can be marketed on a sound,scientific basis.
Aboriginal groups across northern Australia have expressed great interest in becoming involved with mud crab aquaculture development. This project will provide for the supply of commercial quantities of mud crablets, which will support their future involvement.
Both the Northern Territory and the Queensland Government agencies are dealing with a steady stream of inquires regarding the availability of crablets and also the release of mud crab farming technology. This project will help meet that demand.
Mud crab aquaculture will be the focus of both industrial scale aquaculture (similar to prawn farming) development and of appropriate, ecologically friendly farming systems for coastal aboriginal communities.
In time mud crab aquaculture will enable the marketing of mud crabs, both for the local and export markets to become consistent, reliable and of an assured quality. It will also provide the opportunity for the development of a range of products including soft shell crab, crabs of a variety of sizes and a range of crab meat products.
Scaling up of research results to commercial hatchery and nursery systems will overcome two of the major obstacles to development of mud crab aquaculture in Australia identified in the draft mud crab industry development plan (which was an attachment to our previous application this year).
This project will support diversification of pond based marine aquaculture in tropical and sub-tropical Australia.
Any animal which is being farmed intensively will encounter a range of health challenges. Identifying disease agents and developing effective management strategies for them is critical. Control of bacteria loading in larval culture was identified in the ACIAR project as a key barrier to overcome in the commercialisation of mud crab culture. This project contains a health component, which will benefit from preliminary work undertaken by Dr John Norton at QDPI Oonoomba over the last few years.
This project is a vital first step in the development of the mud crab aquaculture industry in Australia. Future activities will involve work on digestion, nutrition and grow-out system design to fully commercialise this farming sector.
Final report
Commercially viable techniques for rearing Scylla serrata larvae through to megalops stage have been developed at both the centres involved in the project, the Darwin Aquaculture Centre (DAC) and the Bribie Island Aquaculture Research Centre (BIARC). The methods developed in an earlier ACIAR project (FIS/1992/017) were not generally reliable enough on a larger scale to be considered able to support commercial production, although much valuable information was generated. The methods developed in this project are suitable for use in commercial scale larval rearing of mud crabs and will be able to support the initial development of mud crab grow-out. The techniques were developed throughout the project by carrying out a series of experiments at each centre. These experiments led to the development of an accepted Standard Procedure which has been shown to be a reliable method of producing commercial quantities of mud crab megalops.
The research groups at DAC and BIARC collectively identified three alternate systems of reliably combating catastrophic losses of mud crab larvae that were found to be associated with bacteria during the rotifer feeding phase of crab larval rearing.
The first method is based on the combination of larval rearing vessels that incorporate design features that keep larvae and food continuously well mixed and suspended, combined with strict hygiene requirements. This included daily manual cleaning of tank surfaces and significant water exchange.
Secondly it was demonstrated that the prophylactic use of oxy-tetracycline (OTC) could be used to control bacterial larval disease. Using OTC as a tool, various operational parameters were investigated to optimise production.
Thirdly, a method was developed where the rotifer feeding phase was replaced by the use of decapsulated Artemia cysts as larval feed for the first few days of culture.
Keywords: Scylla serrata, mud crab, aquaculture, larviculture, zoea, megalops, crablets.
