This project was prompted by poor or variable availability of wild commercial scallop spat for fisheries enhancement and farming in southern Australia and by generally poor and variable success of commercial oyster hatcheries in earlier attempts to fill this shortfall.

Scallops from Jervis Bay, routinely sampled for breeding condition over a three year period proved to be a poor and unreliable source of ripe ready-to-spawn scallops for immediate use in the hatchery. This prompted the development of reliable hatchery conditioning techniques that have enabled routine spawning of scallops throughout the year. Improved methods of spawning induction, fertilisation, incubation and larval rearing, have similarly been developed though systematic investigation and experimentation.

Generally low and variable hatchery success experienced with this species of scallop prior to and during the first year of this project was found to be caused by its high susceptibility to vibriosis, a common bacterial disease experienced by bivalve hatcheries throughout the world

Altered rearing equipment in conjunction with improved husbandry developed during this project have been identified as the best method of combating this disease. A trial using a 20 000 l hatchery tank instead of standard 1000 l experimental tanks, resulted in 90% (9 million) of larvae reaching the settlement stage in 14 days. These are the highest growth and survival rates reported for this species.

Satisfactory growth and survival rates have also been achieved using a standard 1 000 1 rearing vessel but with continuous rather than batch feeding and seawater exchange. The validity and reliability of these altered rearing systems are being rigorously evaluated in ongoing research.

A multi-tiered (stacked tray) upwelling nursery system has been developed as an interim cost effective method of producing large (up to 500 000) batches of 10 to 15mm juvenile scallops. These are being used in a follow-up scallop fisheries enhancement project initiated in October 1994.