Moreton Bay mud bug stock assessment
Assessment charts
© Queensland Government
© Queensland Government
Why did we assess the mud bug stock?
In 2023, Fisheries Queensland completed the first stock assessment of the east coast mud bug stock.
The 2023 mud bug assessment used a delay-difference biomass model based on previous stock assessments. The assessment used the most current biological, survey and commercial catch data to estimate the:
- biomass of the biological stock
- fishing pressure on the biological stock.
In the 2023 assessment for mud bugs, 13 model scenarios were run, covering a wide range of modelling assumptions. Seven scenarios had convergence problems, or diagnostics that indicated issues.
The non-target nature of the fishery combined with fishery-dependent catch rates being the primary data set for model tuning makes assessment difficult. The status of the mud bug stock is undefined. The general trajectory across the 13 scenarios shows the biomass experienced a decline from the period of 1968 until the mid-1980s, then slowly recovered since that time.
Stock assessment project team
The project team had a wide range of skill sets and included:
- managers, scientists, monitoring and data specialists from the Department of Agriculture and Fisheries
- 3 industry representatives
- an external scientist.
The team operated under a terms of reference (PDF, 207.9KB) to ensure a transparent and evidence-based approach.
We thank the project team for contributing their time and knowledge, and engaging constructively over the course of a 16-month project.
We acknowledge the significant time commitment and deep operational and technical expertise of our industry representatives. The project has benefited greatly from their input. Future assessments should continue to engage with industry members to further enhance assessments and build collaboration between industry and government.
Next steps for fishery management
Under the Queensland harvest strategy policy (PDF, 1.46MB) and Trawl fishery harvest strategies 2021–2026, management strategies are applied to keep stocks above the limit reference point (20% biomass) and set a target reference point to manage stocks toward.
The trawl fishery working group:
- provides advice on implementing the fishery harvest strategy
- considers what management changes may be needed to respond to the stock assessment
- may suggest future research or monitoring activities to improve the confidence of the stock assessment.
The working group includes representatives from harvest, post-harvest and conservation sectors.
More information
Read the Stock assessment of Moreton Bay bugs (Thenus australiensis and Thenus parindicus) in Queensland, Australia report—with data to December 2021.