The monitoring and assessment of prawn populations in New South Wales (NSW), Australia, has been identified as a continuing research priority by both the fishing industry and the fisheries managers. This dissertation presents a series of dynamic population models developed to evaluate the status of the eastern king prawn (Melicertus plebejus) and eastern school prawn (Metapenaeus macleayi) populations within NSW and to analyse the relative performance of a number of alternative management strategies involving the three fisheries that target these species. Monthly commercial prawn catch and effort data from 1984 to 2006 were used to calibrate the stock assessment models. Where possible, the results of previous research were used to develop the structure of the model and to provide estimates of biological parameters. A process of increasing model complexity, including the addition of physical processes, such as river discharge events and economic considerations, was undertaken in an attempt to develop the most appropriate model for the analysis of management strategies. The first model presented was used to undertake a single-species assessment of the eastern king prawn stock and was based on a delay-difference population model with four different representations of recruitment. This model was calibrated to observations using the Bayesian sampling/importance re-sampling method and used to test the effect of significant changes in the future catch on the stock. The second model presented is a size-based metapopulation model which incorporated the dynamics of school prawns over three habitats, being harvested by three different fishing methods. This model was used to test the effect of alternative climate variability scenarios on the stock. The third model presented is a multi-species, multi-fishery bio-economic model. This model was used to examine the impact of nine alternative economic scenarios, incorporating various combinations of input costs and product prices. The results from the use of these models indicated that neither of the prawn population appeared to be over-exploited. The analyses also indicated that none of the alternative management strategies were found to stand-out enough to justify a move away from the current management strategy of input controls and spatio-temporal closures, even under a range of future scenarios including climate change and large movements in input costs and product prices.

The monitoring and assessment of prawn populations in New South Wales (NSW), Australia, has been identified as a continuing research priority by both the fishing industry and the fisheries managers. This dissertation presents a series of dynamic population models developed to evaluate the status of the eastern king prawn (Melicertus plebejus) and eastern school prawn (Metapenaeus macleayi) populations within NSW and to analyse the relative performance of a number of alternative management strategies involving the three fisheries that target these species. Monthly commercial prawn catch and effort data from 1984 to 2006 were used to calibrate the stock assessment models. Where possible, the results of previous research were used to develop the structure of the model and to provide estimates of biological parameters. A process of increasing model complexity, including the addition of physical processes, such as river discharge events and economic considerations, was undertaken in an attempt to develop the most appropriate model for the analysis of management strategies. The first model presented was used to undertake a single-species assessment of the eastern king prawn stock and was based on a delay-difference population model with four different representations of recruitment. This model was calibrated to observations using the Bayesian sampling/importance re-sampling method and used to test the effect of significant changes in the future catch on the stock. The second model presented is a size-based metapopulation model which incorporated the dynamics of school prawns over three habitats, being harvested by three different fishing methods. This model was used to test the effect of alternative climate variability scenarios on the stock. The third model presented is a multi-species, multi-fishery bio-economic model. This model was used to examine the impact of nine alternative economic scenarios, incorporating various combinations of input costs and product prices. The results from the use of these models indicated that neither of the prawn population appeared to be over-exploited. The analyses also indicated that none of the alternative management strategies were found to stand-out enough to justify a move away from the current management strategy of input controls and spatio-temporal closures, even under a range of future scenarios including climate change and large movements in input costs and product prices.

Thesis by publication. / Thesis (PhD)--Macquarie University (Division of Environmental & Life Sciences, Graduate School of the Environment), 2007. / Bibliography: p. 267-303. / General introduction -- Redescription of two species of wobbegongs (Chondrichthyes: Orectolobidae) with elevation of Orectolobus halei Whitley 1940 to species level -- Using recreational scuba-divers to survey the relative abundance and distribution of wobbegong sharks (Family: Orectolobidae) in New South Wales, Australia -- Observations of localised movements and residence time of wobbegong sharks (Orectolobus halei) at Fish Rock, New South Wales, Australia -- Length-frequency distribution, length-length, mass-mass and mass-length relationships of wobbegong sharks (Genus Orectolobus) commercially fished in New South Wales, Australia -- Quantitative diet assessment of wobbegong sharks (Genus Orectolobus) in New South Wales, Australia -- Reproductive synchrony of three sympatric species of wobbegong shark (Genus Orectolobus) in New South Wales, Australia -- Age and growth of wobbegong sharks (Genus Orectolobus) in New South Wales, Australia. / In New South Wales, Australia, wobbegong sharks (Orectolobidae) have been commercially targetted by the Ocean Trap and Line Fishery since 1991. A catch decrease of ca. 50% in a decade lead to concern over the sustainability of the fishery and to wobbegongs being listed as vulnerable in NSW under the World Conservation Union Red List assessment. The aim of this research was to investigate wobbegong biology and ecology in relation to its fishery to provide essential data and information for sustainable management of the woggegong fishery. Biological data was obtained from 904 wobbegongs collected from commercial fishing boats, using setlines and lobset pots and by scuba diving. previously two species of wobbegongs were known to occur in NSW: the spotted wobbegong (Orectolobus maculatus) and the ornate wobbegong (O. ornatus). This study discovered a new species (O. halei) described as a subspecies by Whitley (1940), but which had been syonymised with O> ornatus due to a lack of taxonomic investigation. / Mode of access: World Wide Web. / 307 p. ill., some col., maps