Developing a cost-effective monitoring regime and stock assessment for Sand Flathead in Tasmania
Sand Flathead account for well over half of the total catch (by numbers) taken by marine recreational fishers in Tasmania and represent the mainstay of Tasmania's recreational fishery. Furthermore, since the recreational catch of sand flathead is more than 20 times the commercial catch, trends in commercial catch and catch rates are of little value in inferring changes in stock status. This has meant that fishery independent or novel assessment methods are required. To date, IMAS has implemented a research program focused on sand flathead in the south-east of the state that provides a spatially restricted, perspective and semi-quantitative evaluation of stock condition. Given the significance of the species and a status of 'depleting' in the latest stock assessment report, there is a need to implement a more comprehensive stock monitoring approach throughout the state that can support the development of a spatially explicit quantitative stock assessment model. There is also a need to determine the appropriate spatial resolution to apply to the stock assessment model. As such, there is a need to understand the extent of adult movement and ontogenetic connectivity of regional sub-populations of sand flathead throughout Tasmania. In addition, by collation of biological data sets from historical studies and surveys conducted around Tasmania the extent and direction of potential changes in population size structures, and life history characteristics will be investigated. Where possible collated biological data will be used to assess spatial and temporal changes in life history characteristics to assess the implications of selective excessive fishing pressure and/or past and future climate change effects for this species.
Recreational Southern Rock Lobster tagging program – assessing current data and modelling assumptions and approaches to establish a robust estimate
Victorian recreational lobster catches are increasing in many areas due to a range of issues including population growth in coastal communities and efforts to promote fishing through initiatives such as "Target 1 million". Understanding these catches which in some areas is on par with commercial catches is critical for sustainable management of the fishery (for both sectors) and informing resource allocation discussions. The Victorian Fisheries Authority (VFA) has been conducting a recreational tagging program to estimate recreational southern rock lobster catches for the last two seasons. Uptake and compliance with tagging has been high, however reporting of tag usage has been more problematic with the fate of 30,419 of the 92,326 tags issued in the first (2017/18) season remaining unknown. This project will run a recreational diary/phone survey (as used in Tasmania) in parallel with the upcoming 2019/20 tagging season to calibrate the tagging program and provide a comparison of the methods. This will enable a calibration of the tagging based catch estimate and guide management as to the future applicability of both methods.
Incorporating recreational catch estimates in stock assessment models remains challenging due to i) a lack of catch estimates prior to the commencement of surveys and ii) potential reporting biases in survey results. This project will develop a protocol for incorporating recreational catch estimates in a robust manner that specifically addresses these concerns and is aimed at increasing model accuracy and robustness to future changes in recreational catch whilst promoting stakeholder confidence in the utilised approach.
A disadvantage of conventional tagging systems is the requirement of issuing plastic tags and the consequent costs and environmental impacts. In consultation with VFA and stakeholders this project will investigate alternative smart-phone based 'tagging' systems that avoid this issue and develop a guide for future implementation of such a system.