There are three commercial Vongole fisheries in South Australia: Port River (Section Bank), Coffin Bay, and the West Coast (Streaky, Smoky, and Venus Bays). Total catch is ~70 t per year, with a value of ~$2.5 M annually. The Port River fishery is closed due to very low stock abundance and recovery has not occurred despite a 10-year closure since 2011. Based on biomass surveys in 2020/21 the Coffin Bay fishery, which has fishing areas that have historically contained Vongole that grow quickly and can be readily harvested, had a 20% quota reduction in 2021/22 in response to the low abundance of Vongole above the minimum legal length. Although, in 2021/22, this fishery has since recovered and is classified as sustainable.
In the Coffin Bay and West Coast fisheries, three Katelysia species are harvested: greys, yellows, and whites. In both fisheries, commercial fishers have reported areas with Vongole density so high that it might be supressing growth and productivity due to competition for space and resources. Vongole in these high-density areas seldom reach the legal minimum length of 30/35 mm and are rarely fished. The commercial Vongole fishery has therefore highlighted the need to understand factors influencing growth rates and to test whether translocation of sub-legal Vongole from these high-density areas can be used to increase Vongole growth and productivity within these areas, and improve less productive fishing grounds elsewhere, thereby raising overall fishery profitability.
Our study aims to 1) assess the viability of translocating sub-legal Vongole in Coffin Bay from areas with high densities of Vongole to areas with low/no densities of Vongole using two release and two tagging methods, and comparing predation, growth, and survival of relocated/translocated animals to provide fishers with the knowledge and tools underpinning translocations; 2) build on existing cost-benefit analysis knowledge and tools (i.e. FRDC 2005-217, FRDC 2008-076, FRDC 2016-213, FRDC 2020-116) to quantify the economic/productivity outcomes of Vongole translocation; and 3) build fisheries research capacity and capability through a 'supplemental’ student project. The aims of the ‘supplemental’ student component (PhD, Flinders University) are to assess the biological aspects of Vongole recruitment (e.g. size of maturity, egg production, viability of larvae) and evaluate environmental triggers that influence Vongole recruitment, metamorphosis of eggs to larval phase, and larval substrate settlement.
This project directly addresses the Vongole industry’s high-priority research needs and will showcase the potential for translocation to increase fishing yield, value, and profitability. The ‘supplemental’ student project will evaluate Vongole recruitment and will occur in parallel with, but independent from, the core project.
