Sufficient pure ciguatoxin (0.5 mg of CTX-1) has been isolated from moray eel viscera to allow the immunisation of mice and screening of antibodies to ciguatoxin. It is determined that in vivo immunisation techniques were most likely to yield antibodies using related toxins as models of ciguatoxin. The model toxins used included brevetoxin, okadaic acid and tetrodotoxin. Using the same approach it was determined that the in vitro immunisation techniques investigated were inappropriate. It appears essential that ciguatoxin be conjugated to a carrier protein to allow production and screening of antibodies to ciguatoxin. The use of unconjugated toxin, either for immunisation or screening, appears inappropriate. The conjugation of ciguatoxin to a carrier protein has not been achieved despite considerable effort. Consequently, it was not possible to achieve the overall goal of the project. Until it is confirmed that ciguatoxin possesses the functional groups that allow the toxin to be conjugated to a carrier protein, work towards the development of antibodies to ciguatoxin cannot proceed.

During this project 595 potentially toxic fish samples were tested for toxin content. This included numerous samples of moray eel viscera and numerous portions of fish involved in ciguatera in Australia.

During this project two new ciguatoxins (CTX-2, 0.3 mg; CTX-3, 0. 1 mg) were also isolated from moray eel viscera. These toxins were determined to be less oxidised forms of ciguatoxin. Analysis of moray eel toxicity indicated that these fish may excrete ciguatoxin over time.

Using mouse bioassay, the efficiency of extraction of ciguatoxin was determined to be > 50% in fish flesh spiked with ciguatoxin. Mouse assay is not suitable to detect low toxicity fish flesh samples but is useful as a confirmatory assay for fish with a toxicity high enough to demonstrate moderate to severe clinical effects.

Future studies are required to resolve questions on the chemistry of ciguatoxin. These studies are presently underway. With this information the project can proceed to the production of antibodies to ciguatoxin using the procedures and protocols developed during this project.

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.

The aim of this project was to farm, on a pilot commercial scale, two indigenous species of marine fish: snapper, Pagrus auratus; and mulloway, Argyrosomus hololepidotus.

The project involved:

• development of hatchery techniques;
• intensive rearing of larvae;
• transport of live fish;
• design, construction and testing of seacages for research;
• grow-out of juvenile fish in tanks and seacages;
• identifying and treating disease outbreaks in seacages;
• obtaining production data; and
• obtaining preliminary marketing information.

The project sought to provide information on the possibility of enhancing wild stocks of mulloway by the release of fish originating from a hatchery.

The First Australasian Scallop Workshop was held in Taroona, Tasmania in July 1988 and was attended by 51 participants from Australia, New Zealand and Japan.

It proved to be a very valuable forum for exchange of ideas on scallop biology, management and culture. The organisers of that workshop, Mike Dredge, Will Zacharin and Lindsay loll, along with Richard McLoughlin must be thanked again for taking the initiative in organising the second Australasian Scallop Workshop at the East Coaster Resort, Triabunna, Tasmania, 23-25 March 1993.

Support for the second Australasian Workshop has been provided by the Fishing Industry Research and Development Corporation, the Commonwealth Department of lndustry Technology Employment and Commerce, state departments responsible for fisheries in Queensland, Western Australia and Tasmania, and the CSIRO Division of Fisheries. Thanks for this support are extended to each of those bodies, in the context of both the workshop and publication of the proceedings.

Scallop resources are notoriously difficult to manage because of wide fluctuations in recruitment and problems with harvesting technology; this emphasises the need for workshops of this nature to obtain maximum benefit from dissemination of knowledge and experience in scallop biology and management.

Recently we have seen progress towards more rational management of scallop resources in this part of the world and for the first time in southeastern Australia there appears to be a cooperative and constructive approach to scallop fishery management. While scallop stocks in Victoria and Tasmania have been in decline in recent years, the saucer scallop fisheries in Western Australia and Queensland have stabilised or are expanding. The background to such variation, and of the associated problems of recruitment variability in scallops from W.A. to Tasmania are discussed in some detail.

It is pleasing to note also that an appropriate time allocation has been made towards considering the impact of our scallop harvesting technology, both on the scallops themselves and on the environment which sustains them. It is clear that the industry cannot afford to continue using inefficient and destructive fishing gear if better technology is available.

The workshop was perfectly placed in Triabunna to explore recent progress in scallop culture and reseeding. Free exchange of ideas on methodology and technology relating to these activities shows promise that scallop enhancement may achieve its full potential in the coming years. The enhancement project in Tasmania has been operating since 1987 and all types of difficulties from appropriate gear to aspects of marketing are still being researched by the company.

This workshop provided an opportunity for biologists, managers, marine farmers, fishers and others with an interest in scallops to expand their understanding of scallops and pass on some of their hard earned knowledge and experience to others.

The make-up of this workshop is unusual, to say the least, in that organisers have brought together so many facets of industry and have recognised the importance of marketing to the scallop fisheries.

Finally, some public health issues associated with scallop fisheries around the world have been brought to the workshop's attention. Such issues, largely associated with dinoflagellate-derived toxins, have not been a major issue in Australia to this time. Their significance in an international context, and their potential to affect scallop marketing and fisheries in Australia, is a major consideration for the future.