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Objective 1. Measure spatial and temporal trawl frequency of scallop grounds using VMS data. This will provide a relative measure of how often individual undersized scallops are caught and put through a tumbler 2. Estimate discard mortality and growth rates for saucer scallops using cage experiments. 3. Evaluate the current management measures, in particular the seasonal closure, rotational closure and seasonally varying minimum legal sizes using stock assessment and management modeling models. Recommend optimal range of management measures to ensure long-term viability and value of the Scallop fishery based on a formal management strategy evaluation. Outcomes acheived to date: 1. Improved understanding of the survival rates of discarded sub-legal scallops; 2. Preliminary von Bertalanffy growth parameters using data from tagged-and-released scallops; 3. Changing trends in vessels and fishing gear used in the Queensland scallop fishery and their effect on scallop catch rates over time using standardised catch rates quantified; 4. Increases in fishing power of vessels operating in the Queensland scallop fishery quantified; 5. Trawl intensity mapped and quantified for all Scallop Replenishment Areas; 6. Harvest Strategy Evaluations completed.

In the Queensland, Australia, scallop fishery, the scallop catch is graded at sea using a specially designed grading machine called a "tumbler." Experiments were conducted to determine the effect of repeated trawl capture, grading, and discarding on the survival of sublegal saucer scallops Amusium balloti. Scallops were caught within an area closed to commercial fishing and known to contain dense scallop beds. The trawled scallops were randomly divided into 2 groups, tumbled and control, and subjected to up to 4 tumbles and/or trawls before being caged for 2.5 days adjacent to the trawl grounds. Increased levels of both trawling and tumbling were found to decrease significantly the survival of sublegal scallops. Although 83% of scallops survived repeated intensive trawling (4 consecutive tows), survival fell to 64% when scallops were also graded using a commercial tumbler. Survival was high for both tumbled and control sublegal scallops after 1 trawl (97% and 98%, respectively).