It has become apparent to commercial divers within the NSW abalone fishery that previously productive areas of reef are now supporting high densities of sea urchins, and correspondingly low densities of abalone. This change has contributed, together with pressure from the commercial and recreational fishery, illegal poaching, disease and pollution, to a decline in the sustainable yield from the population. The current development of the sea urchin fishery in NSW provides the opportunity to re-establish populations of abalone on once productive areas of reef over a large spatial scale. Natural recolonisation of areas of reef will be limited because of the restricted dispersal of larvae from their parents.
A variety of techniques are already being used to help re-establish populations of abalone on depleted areas of reef in NSW. These include the clearance of sea urchins to allow natural recovery, together with the transplantation of broodstock to help increase the speed of recovery. All these techniques are very labour-intensive. The deployment of seed produced from wild abalone provides a significantly more powerful technique to rapidly enhance populations of abalone on depleted reefs over a large-scale. Protocols for the conditioning, spawning and rearing of blacklip abalone are already well established and provide the framework for the year-round production of seed. Techniques for the large-scale deployment of seed have been developed in other states, but recent advancements in our knowledge of settlement substrates suggest further improvements can be made. Similarly, deployment techniques will need to be adapted for the unique conditions on reefs in NSW, and particularly the presence of the sea urchin, Centrostephanus.
With the development of techniques to allow the successful, large-scale release of abalone seed to coastal reefs in NSW, there are likely to be significant benefits to the associated fisheries. In particular, the potential exists for increases in the sustainable yield of the fishery of up to several hundred tonnes per year, or several million dollars.
Final report
Several critically important steps to achieving the central long-term aim of this project namely, cost-effective enhancement of abalone fisheries using hatchery produced seed stock, were achieved. The first was year-round controlled temperature conditioning and spawning of captive broodstock. This provided impetus for funding and guidance for practical implementation of a complementary R & D project (FRDC 2000/204) to refine and improve this technology in relation to blacklip and greenlip abalone. This controlled breeding technology is in turn providing a number of important flow-on benefits to the abalone aquaculture industry in southern Australia. Most importantly it is facilitating an industry-wide selective breeding program through facilitated synchronisation of spawning that will enable pair crossing and identification of specific genes for faster growth.
Key Words: Abalone, Fishery, Aquaculture, Hatchery, Broodstock, Production, Deployment, Rehabilitation, Reseeding, Enhancement
