Theme B: Modelling and assessing the effectiveness of releases for fisheries management and conservation
15. STOCK ENHANCEMENT IN GREENLIP ABALONE: POPULATION AND ECOLOGICAL EFFECTS
Anthony M. Hart, Frank Fabris, Lachlan Strain, Mark Davidson, Jamin Brown
Western Australian Fisheries and Marine Research Laboratories,
PO Box 20, North Beach, Western Australia, 6920, Australia
Anthony.hart@fish.wa.gov.au
Stock enhancement experiments were carried out on Haliotis laevigata populations. Methodologies included a large-scale BACI experiment (42 sites), a carrying capacity experiment, which involved a high-density release at 2 sites, and a detailed survey of abalone populations and ecological parameters. Increased densities were detected for most age classes, although fishing mortality began obscuring the effect by age 5+. Age 4+ animals showed the clearest result, with no difference between enhanced and control sites at 6, 12, and 18 months post-release, and then a 300% increase at enhanced sites at 30 months post-release. Overall, this single release of Age 1+ animals in May 2006 had doubled the total density by November 2008. In the carrying capacity experiment, densities initially increased rapidly (by up to 800%), however had stabilised at a 400% increase after 2.5 years (2 to 8 per m2), with the enhanced cohort representing 50% of the population. A PERMANOVA analysis of ecological similarity detected no effect of enhancement, although changes in algal % cover were detected at both control and enhanced sites. Overall our study suggests that, as long as release densities are controlled within natural limits, successful stock enhancement can be attained for this species, with minimal ecological impacts.
Call For Papers