Port Phillip Bay and Bass Strait scallop research
Final report
During the 3 years of the study, scallop spatfall was observed to occur over a short period (October-December) after the scallops had spawned in spring. Growth was rapid and scallops reached an acceptable harvestable size of 70mm within 16 months. Spatfall one year can therefore be related to recruitment during the next. Years of high and low spatfall were reflected in subsequent differences in recruitment. Though more years' data are required, indices of spatfall provide managers and fishermen with predictive information on likely recruitment strength one year in advance.
Each year the strength of recruitment and the residual stock size were estimated from the results of surveys by SCUBA divers. The results have shown that commercial viability of the fishery is primarily dependent upon recruitment each year. Residual stocks are normally insufficient to support the fishery in the event of poor recruitment.
Estimates of growth and mortality rates determined from tagging and data on seasonal changes in meat yield have been used to develop a mathematical model which can be used to determine number of scallops available each season and yields obtainable from different management strategies. Estimates from annual survey, of stock abundance and mean scallop size at the beginning of each year provide the data for the model.
As a result of the research program, the need to continue monitoring spatfall in Port Phillip Bay and to conduct surveys of recruitment strength each year has been identified. These data are necessary for fisheries managers to maintain the ability to manage the stocks by quota system.
South East Fishery Industry Development Subprogram: facilitation, administration and promotion
People development program: 2014 FRDC Visiting Expert Award- Dr Dan Gwinn
Dan Gwinn is an internationally renowned quantitative ecologist with technical expertise in several key areas that will benefit the management of Australia’s fisheries. Of particular interest to FRDC are his expertise in parameter estimation, monitoring design, and fisheries modeling. Dr Gwinn is experienced in developing innovative estimation methods to specifically deal with the inherent issues with imperfect data as is the case for fisheries and ecological research. Dr Gwinn’s work in this area has focused on the customization of statistical models to account for the specific idiosyncrasies of data sets to best extract biological information and inform the management decision process. Often, this work had included developing innovative analyses of existing data sets to answer new questions. Dr Gwinn also has expertise in use of analysis tools including the application of stochastic simulations for evaluating and optimizing experimental and monitoring designs, which are particularly useful for determining the most fiscally efficient sampling designs for meeting monitoring objectives.
We propose to facilitate a study tour for Dr Gwinn to enable him to meet with fisheries researchers and managers from several jurisdictions to review and discuss key freshwater and marine projects, present to the research and management community on innovative methods being employed in the United States to address common issues, and workshop strategies to enhance adoption of R&D outputs.
We believe that this visit will deliver significant benefit to the future management of Australia's fisheries resources.