Critical to the Harvest Strategy for the Qld Mud Crab Fishery are processes for monitoring and assessing fishery performance. Currently, the empirical and estimated indicators for this fishery are based on non-validated harvest and effort. Proposed fishery reforms (i.e., prior reporting of landings and 'market' tagging of harvested crabs) should improve harvest data reliability. Qld GMC are effectively a data-limited species because they cannot be reliably aged, associated effort data is incomplete and potting is a passive fishing technique. Commercial CPUE may not represent changes in population abundance due to variable catchability, hyper-stability and serial depletion. Additionally, there is no index of female abundance nor a male:female ratio to inform spawning-recruitment relationships. It is generally assumed that conservative management of GMC ensures their sustainability. However, evidence from the Northern Territory Western Gulf of Carpentaria suggests that GMC are vulnerable to environmental events (drought + heat = 2015 cohort failure). Gaining a rudimentary understanding of critical aspects of the GMC life cycle in Qld would be prudent (i.e., female abundance, spawning vicinities).
A Total Allowable Catch (TAC) is a key aspect of reform to Qld fisheries. The initial TACs for Qld GMC were informed by a modified catch-MSY analysis (Northrop et al., 2019). Catch-MSY is widely applied in Australian fisheries to data-limited species (FRDC 2017/102). The assessment was performed at large spatial scales (East Coast and Gulf). However, this fails to capture regional variability in spawning-recruitment processes that impact on harvestable biomass e.g., larval dispersal due to oceanic circulation patterns and survival of juvenile crabs due to regional rainfall, flow, temperature, and sea level variations. The proposed research is needed (in the short-term) to gather appropriate quantitative biological information and to develop (for the long-term) a means to cost-effectively monitor Qld GMC populations to support a data-moderate stock assessment approach. The research also aims to address some of the critical knowledge gaps in GMC life history that have been unresolved for over 40 yrs.