In November 1992, this project commenced with the development of methods for the evaluation of striped trumpeter (Latris lineata) larvae cultured by the Finfish Development Program (FDP). The first year was spent in the selection of digestive enzymes for investigation and the modification of methods for their detection. In addition to the digestive enzymes selected, lipids and glycogen deposits were also studied to provide an indication of the status of larval energy uptake and storage. The project used the observation and measurement of samples of larvae to provide an assessment of growth, development and the general health of larvae. The methods developed by the project have been detailed in a Technical Report published by the DPI&F.

Preserved samples of larvae were processed, thin-sectioned and stained to provide information on the development of the swimbladder and the gut with its associated organs, as well as the presence of digestive enzymes at different stages of growth. The timing and method of swimbladder inflation, as well as the development of the digestive tract prior to metamorphosis, was investigated, providing valuable basic biological information on the species. This information was used to modify larviculture systems and techniques and resulted in the successful culture of juvenile striped trumpeters, banded morwong and greenback flounder in the 1994 rearing season.

The overall goal of the present project was to establish a long term puerulus settlement monitoring program for the southern rock lobster (Jasus edwardsii) in Tasmania. Exploratory sampling was conducted throughout much of the Tasmanian coastline to determine key sites suitable for long term monitoring. Experiments were also conducted to determine guidelines for the use of collectors and to determine whether individual sampling stations could provide a representative indication of inter-annual variation in settlement throughout a larger area.

Exploratory sampling around Tasmania found both small and large scale spatial variation in settlement levels. In general settlement rates obtained on the west coast were considerably lower than on the east. Distinct seasonality of settlement was also observed and differences existed in the timing of settlement between areas. Two peaks in settlement occurred each year on the east coast, these being winter (June to September) and summer (November/December). The timing of peaks on the south coast were similar to the east coast except that the summer settlement often occurred one to two months later. On the west coast, the primary period of settlement appeared to be from January to April.

Because of differences in the timing of settlement between the east, south and west coasts, it was considered important that long term monitoring be conducted within each of these regions. A total of 8 site were established for long term monitoring. This comprised 4 sites on the east coast (Bicheno area), 1 site in the south east (South Arm), 2 site in the south (Recherche Bay) and 1 site on the west coast (King Island). The number of collectors currently in use will allow inter-annual settlement declines of between 30 and 50 percent to be detected as being significant on the east, south east and south coasts, but on the west coast, declines would need to be nearly I 00% to be detected as being significant. The number of collectors required to detect changes was highly dependant on catch rates with lower numbers of collectors being required at sites with high catch rates.