2005/029 Factors limiting the resilience and recovery of fishing abalone populations

By Craig Mundy

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.