Filling knowledge gaps on Giant Mud Crabs (Scylla serrata) in Queensland

Abstract

The Giant Mud Crab is an iconic and major fishery species in northern Australia, with approximately 65% of the Australian harvest coming from Queensland waters. Conservative management (male only harvest, 150 mm carapace width minimum legal size) has been a long-term strategy of this Queensland fishery, with an output control (a total allowable commercial
catch) introduced in 2021. Recent research (FRDC 2019-062) measured population parameters (e.g., genetic connectivity, size-at-maturity, reproductive seasonality, and female insemination rates) across multiple regions to inform the fishery’s Harvest Strategy. Results indicated that there are small differences in regional biology, and that despite high fishing mortality on legal males in some regions, there is no strong evidence that this is a threat to the sustainability of Giant Mud Crab populations in Queensland. Results also indicated that most mature females were in their first mature intermoult and concurs with the paradigm that the offshore female spawning migration has likely high natural mortality, which may need consideration in
jurisdictions where females are subject to harvest.