Area closure is the only management action yet to be attempted to reverse the declining performance of the eastern zone abalone fishery (see Section B2). However, the socio-economic cost of closures in large areas of the fishery would be significant, and would create considerable tension among researchers and stakeholders. Importantly, area closures have not been successful as a management action to rebuild the Californian and British Columbian abalone fisheries. Therefore there is a need to identify tools to promote rapid and long term recovery, and better alternatives to full closure.
It is likely that the key factors responsible for ensuring population recovery will be the same factors that ensure populations maintain resilience. This proposal thus also meets the need to determine the most effective and efficient means of preventing future stock depletions.
Stock enhancement has been the subject of a North American symposium on rebuilding abalone stocks, and the focus of two major FRDC funded research programs (1994/005; 2001/033). Restocking of populations by releasing larvae and/or abalone seed (juveniles) was ineffective in Australia, Japan and North America, and is also prohibitively expensive. On the other hand, translocation of mature individuals may provide substantial benefits over the release of larvae and juveniles, and if successful, would be considerably more cost-effective (Tegner 2000; Campbell et al 2000). Translocation of mature abalone into depleted populations would also allow us to fast-track the recovery process.
In addition to testing translocation of mature abalone as a tool for rebuilding depleted abalone populations, there is a clear need to understand the scale of influence of a translocation exercise. For example, if we were looking to facilitate recovery along a 50km length of coastline, would translocation of animals to one location in the middle serve to seed the entire area, or would we have to translocate animals to five locations spaced 10km apart, or 50 locations at 1km apart? The scale of influence of a translocation event would therefore be a crucial component of assessing translocation as a management tool.
Understanding the key ecological processes limiting stock recovery will enable management strategies to be implemented that either remove impediments to recovery, or trigger stock recovery. The improved governance of wild fisheries addresses FRDC CHALLENGE 1: Improve the sustainability of natural resources supporting wild-catch and aquaculture.
Knowledge of recovery processes is required if the abalone fishery is to be managed sustainably, and is to continue to provide an important economic resource to Australia’s rural coastal populations. Knowledge of ecological processes such as those underpinning stock recovery are clearly identified in the Australian National Research Priorities - An Environmentally Sustainable Australia - Sustainable use of Australia’s biodiversity.
By understanding the key processes of reproductive success, recruitment and early survival, the proposed research addresses the Australian Marine Science and Technology Plan Program 1 – Understanding the Marine Ecosystem, by contributing to Objective 6 - Understand the biological processes in Australia’s oceans and Objective 7 - To understand the dynamics of Australia’s marine habitats and ecosystems. This research also addresses Program 6 – Using and caring for the Marine Environment, specifically Objective 6 - To improve the productivity and sustainability of the wild harvest fisheries, and to improve understanding of the relationships between fished stocks and the ecosystems that support them.
This project covers three of the high priority tasks in the current Tasmanian Abalone Strategic Research Plan (2005-2009): Recruitment, Stock Recovery and Stock Enhancement. The dynamics of stock recovery was identified as the highest priority research issue in 2004 by the Abalone Research Advisory Group.
References cited:
Campbell A (2000) Review of northern abalone, Haliotis kamtschatkana, stock status in British Columbia. In: Campbell A (ed) Workshop on rebuilding abalone stocks in British Columbia. NRC Canada, Nanaimo, BC, pp 41-50.
Campbell A, Lucas BG, Parker G (2000) Discussion on an Experimental Approach for Northern Abalone Stock Rebuilding in British Columbia. Fisheries and Oceans Canada.
Tegner M (2000) Abalone (Haliotis spp) enhancement in California: what we’ve learned and where to from here. In: Campbell A (ed) Workshop on rebuilding abalone stocks in British Columbia. NRC Canada, Nanaimo, BC, pp 61-71.
Final report
The aims of this project were to:
- Determine the efficacy of translocation of mature abalone for stock rebuilding
- Identify key ecological processes that limit stock recovery
- Quantify the scale of 'spillover' from translocated populations
- Cost-benefit analysis of rehabilitated habitat
Approximately 2000 reproductively mature abalone were successfully translocated to each of three sites in a depleted region of the Tasmanian Eastern Zone fishery. The success of the translocation provides clear demonstration that translocation of abalone can be achieved easily, and at a relatively low cost. Intensive monitoring of abalone at paired Translocation and Control sites over 24 months demonstrated that Translocation of mature abalone as a tool for rebuilding local populations is a feasible and relatively low cost activity, with high levels of survival easily achieved with appropriate handling and transport of abalone.
Surveys of abalone density and movement at the three translocation sites revealed the translocated abalone responded differently at each site, with increased and earlier emigration of the translocated abalone at the sites and areas with low habitat complexity. Larval recruitment to collectors was found to be highly variable among sites, and through time. Investigation of connectivity at different spatial scales using population genetic tools strongly demonstrated that recruitment is highly localised, with very high levels of self-recruitment to sites or populations. Translocation of wild abalone can only be used if there is an adequate source of mature abalone that are surplus to the requirements of the fishery. For this reason, it is expected that the circumstances where translocation of wild abalone for the purposes of stock rebuilding can be undertaken will rarely occur.
