Testing abalone empirical harvest strategies, for setting TACs and associated LMLs, that include the use of novel spatially explicit performance measures
CSIRO Oceans and Atmosphere Hobart
Recent declines in Eastern Tasmania (Tarbath & Gardner, 2012) and Tiparra Reef in South Australia (Chick & Mayfield, 2012) suggest a potential for changes in productivity. Further challenges to successfully managing abalone include periods of poor recruitment in some areas, rising Australian east coast temperatures, the Victorian virus outbreak, toxic blooms in Tasmania, and mortality events in Tasmania. All these challenges to current management indicate the need for more detailed and rapidly reactive and defensible management of Australian abalone stocks. The management strategy evaluation (MSE) framework from FRDC 2007/020 “Biological Performance Indicators for abalone fisheries”, focussed on the utility of classical performance measures. However, the Multi-Criterion-Decision-Analysis Harvest Strategy (MCDA-HS) being developed in Tasmania will integrate classic fishery Performance Measures (PMs) with new Spatial PMs, and include local complexity in growth (the latter are important for the TAC/LML debate). Now GPS data loggers have become compulsory within the Tasmanian fishery (2006/029 – “Using GPS technology to improve fishery-dependent data collection in abalone fisheries”), the need to test these new empirical harvest strategies, that include spatial PMs, is becoming urgent. The MSE framework, therefore needs modification to successfully simulate the new spatial performance measures and then test the performance of the novel harvest strategies. South Australia introduced a non-spatial MCDA-HS without testing and an array of unintended consequences is becoming apparent. To retain confidence in the application of formal harvest strategies with associated decision rules testing the harvest strategies as they are developed remains important. Novel harvest Strategies need to be tested to determine by how much they improve the setting of TACs and associated LMLs. There is a recognized need to interact with FRDC 2011/201: “Implementing a spatial assessment and decision process to improve fishery management outcomes using geo-referenced diver data” so both projects can benefit from each other.
1. Review objectives and logic of having and setting Legal Minimum Lengths in abalone fisheries and how these interact with TAC levels.
2. Conduct Manager/Industry workshops to inform, identify issues, and to select LML/TAC scenarios within particular harvest strategies for testing by Management Strategy Evaluation..
3. Develop new modules for the present Abalone MSE Framework for testing LML/TAC harvest strategies containing multiple empirical performance measures (MCDA) that use spatially explicit PMs.
4. Use the modified MSE framework to test new Multi-Criteria Decision Analysis Abalone Harvest Strategy under development in FRDC 2011/201.
The management of abalone stocks is difficult for many reasons including their high value and the exceptional levels of spatial structuring found in their stocks. In Tasmania, for example, suggestions to change such things as a legal minimum length or introduce a formal harvest strategy to replace the current relatively informal process, always engender high levels of sometimes heated debate. An aim of this work, conducted by Malcolm Haddon and Craig Mundy of CSIRO and the University of Tasmania respectively, was to formally examine the implications of changing legal minimum lengths and the importance of such LML to the management of abalone. This was in the context of using management strategy evaluation to test alternative potential harvest strategies for use, in the first place, within the Tasmanian abalone fisheries. With the advent and growth of more public scrutiny of wild fisheries a need for a more defensible, repeatable, and publically available process for setting abalone TACs had become urgent. This project aimed to contribute to the development of such formal harvest strategies that would both successfully generate workable management advice and be defensible under anyone’s scrutiny.Keywords: Blacklip Abalone, Haliotis rubra, formal harvest strategies, MSE, management strategyevaluation, LML, MLS, legal minimum length.