Risk analysis and sustainability of the southern rock lobster (Jasus edwardsii) resources in SA
SARDI Food Safety and Innovation
A new stock assessment model is required to improve the estimated time series of recruitment, exploitation, and catchability of lobsters in the South Australian lobster fisheries. This information is needed to (a) on its own quantify the current state of the fishery; (b) develop a reliable simulation model to answer important questions like, “what is the “right” TAC in the southern zone fishery, or the “right” amount of effort in the northern zone fishery to achieve the long term goals of these fisheries?”. These questions cannot be answered at the present time with the current SA assessment methods. Of immediate concern is the lack of a capacity to respond to external threats to the industry. The lobster industry is presently exposed and vulnerable to claims of over-fishing because it cannot respond with a defence of its management strategies and practices based on a formal risk assessment. Because the risk of over-fishing is not quantified, the management committees must adopt the precautionary principle which may be costing the industry and the broader community millions of dollars in revenue from foregone commercial catch as well as substantially reduced recreational opportunities. The industry may not be able to capitalise on opportunities for attracting premium prices for their product through certification of the fishery’s sustainability, and may even face problems meeting Australia’s own (future) export requirements unless it can quantify risk. There is no doubt that the industry will require the proposed assessment tools. Securing the proposed capability can either be pro-active, or it will have to be re-active.
1. Undertake a careful review of appropriate models developed and used in other invertebrate fisheries, including those used in Tasmania and Western Australia.
2. Develop a spatial-, sex-, time- and age-dependent model (or equivalently a spatial-, sex-, time- and size-dependent model), taking advantage, where possible, of model components developed elsewhere.
3. Develop a simulation model based on the outputs from the model in (2).
4. Use the simulation model to evaluate various harvesting strategies to empower the fishing industry and managers to make better informed decisions and respond skilfully to critics.
5. Use the model to forecast catch and abundance for individual areas.
6. Use the model to answer the following questions: How much risk is associated with any particular TAC or level of effort? How much more can fishers gain in revenue terms under alternative harvesting strategies while demonstrating long term sustainability with a quantified risk? Which fishing regime produces a sustainable fishery, while, at the same time, maximises catch and revenue? How does the current harvesting strategy compare with to the optimal harvesting strategy? How much more biological information is gained or lost by adopting various harvesting strategies? What are the implications of lobsters' aggregating behaviour for the assessment of the stock?
7. To develop a modelling option that allows management to produce reports consistent with the ESD reporting framework developed by SCFA.
Principal Investigator: Y. Xiao & J. Prescott