Thesis: Determining variation in catchabiity of the western rock lobster (Panulirus cygnus)
This study will investigate and quantify the environmental and biological factors that affect the catchability of the western rock lobster, Panulirus cygnus. Field surveys complemented by expert knowledge and laboratory experiments, will elucidate the significant factors affecting lobster catch rates. Thorough statistical analysis will quantify the effects of these factors so that they can be built into fisheries stock assessment models. This research will be conducted in conjunction with the Fisheries division of the Department of Primary Industries and Regional Development. Broadly, the research aims to standardise, and therefore increase the accuracy of western rock lobster stock assessments. These assessments are an integral tool, informing the majority of management decisions regarding the fishery. By improving their accuracy we can assure both the sustainability and profitability of this economically important resource.
Why my research is important
The western rock lobster fishery a quota-based fishery and is Australia’s most valuable single species fishery, worth around $400 million dollars annually. The annual quota is informed by an annual stock assessment which relies heavily on fishery independent data inputs. As highlighted in recent assessment of the fishery (de Lestang et al. 2016), there are significant catchability factors which are not adequately accounted for in the generation of these independent indices and hence reduce the robustness of the model assessment. Changes to the TAC in either direction, based on unaccounted for biases associated with catchability, can adversely impact on this valuable fishery. Setting the quota too low would affect the industry’s profitability, while setting them too high would affect the spawning stock and risk the sustainability of the fishery. Accounting for the biases impacting on abundance indices used to drive the stock assessment model, and therefore improving the accuracy of the model, will allow the fishery to maintain fishing at an appropriate level, thus achieving maximum economic yield and maintaining a healthy spawning stock. This study will also provide novel insight into the behaviour of P. cygnus that, beyond benefiting the fishery, will increase our understanding of the species and may even benefit similar rock lobster species fisheries and research.