Scallops - research information sheet

A ‘boom or bust’ pattern is typical of scallop fisheries the world over including fisheries for the commercial or ‘Tasmanian’ scallop (Pecten fumatus) throughout southern Australia. For example, the fishery in Jervis Bay, NSW, can produce up to 2,800 tonnes of scallops (current value approx. $4 million), however, this only occurs about once every ten or twenty years. If consistently high scallop production is to be established in NSW, the problem of low and variable recruitment of juvenile scallops must be addressed. Otherwise, a substantial scallop farming industry will need to be established.

Japan has been a world leader in enhancing the yields of wild scallop fisheries having raised fisheries production from about 20,000 to 200,000 tonnes per annum. Juvenile scallops, caught from the wild, are grown to a size of about 40 mm in pearl and lantern cages before being released on the sea bed. Unfortunately, attempts to catch scallop spat in the wild in Australia have been highly variable in their success and in NSW, particularly poor. Cheap reliable hatchery and nursery rearing techniques are therefore needed if our natural fisheries are to be enhanced to provide consistently high yields or if new aquaculture industries based on this species are to be developed in NSW.

Three years of intensive research by NSW DPI supported by a Fishing Research and Development Corporation grant, from 1992 to 1994 led to the development of reliable cost effective hatchery production of scallops. This technology overcomes previous problems of unreliable hatchery production and poor and inconsistent supply of spat from the wild over the subsequent three years (1995 to 1997), hatchery produced scallop seed stock from the Port Stephens Research Centre was used in bottom seeding and farming trials in Jervis Bay. A total of more than four million scallop spat were produced for seeding and farming trials and over 250 000 scallops ranging in size from 20-60 mm were released into Jervis Bay. Major achievements were as follows:

• Reliable, cost efficient techniques for nursery production and suspended fanning of commercial scallops in NSW were successfully developed as was a modified glue attachment suspended culture technique that offers significant advantages over conventional cage and ear-hanging culture methods. Techniques to combat predation, spionid worm infection and biofouling of scallops in suspended culture were also developed.
  
• Cost effective deployment of scallops in Jervis Bay could not be demonstrated due to very diverse and intense predation of juvenile scallops up to and beyond 50 mm shell height at most release sites and to the confounding effects of very rapid dispersion of released stock. Nevertheless results did demonstrate very high survival and acceptable growth rates when naive scallops are deployed under predator proof canopies of cheap lightweight plastic netting originally developed for protecting horticultural crops from moths and birds.

Much of the technology developed in this project has already been commercially implemented in Tasmania.