King threadfin stock assessment—Queensland Gulf of Carpentaria

Chart of 2019 Queensland Gulf of Carpentaria stock assessment biomass estimates and key management actions for king threadfin

© Queensland Government

Chart of estimated harvest for Queensland Gulf of Carpentaria king threadfin from 1945 to 2019

© Queensland Government

Why did we assess the king threadfin Gulf of Carpentaria stock?

In 2020, Fisheries Queensland completed a stock assessment using the most current biological data, and commercial and recreational catch data to:

  • determine the sustainability of fish stocks
  • inform management decisions
  • inform the development of a harvest strategy.

This assessment estimated that the number of adult king threadfin (spawning biomass) was around 5% of unfished levels in the Gulf Regions in 2019. The current assessment estimates that after a period of rebuilding the stock can maintain a harvest of 229 t/year while maintaining the 60% target biomass.

How was the stock assessment conducted?

The 2019 assessment used a stock assessment model called Stock Synthesis, one of the most widely used and tested stock assessment models in the world and is currently used by CSIRO and other Australian fisheries jurisdictions.

A lack of data available for the 2002 assessment caused biomass models to fail and used commercial harvest to produce a management target of 236 t for the Gulf of Carpentaria. The 2019 stock assessment included up to date data on recreational and commercial catch and effort, as well as biological data such as fish length and age.

Findings from the independent review

As best practice, Fisheries Queensland conducts independent reviews of stock assessments and other scientific reports on a regular basis.

An independent review of the king threadfin stock assessment was conducted by Dr Neil Klaer, a former CSIRO fisheries scientist. The reviewer supported the conclusions of the stock assessment results and agreed that the assessment has been competently constructed and is suitable given the available data. He made some suggestions for improvements, including alternative options for catch rate calculations and handling the way king threadfin catchability (the proportion of the stock taken by an operator per day) may be changing over time. The authors have considered these recommendations and will address them in future assessments.

Next steps for fishery management

Under the Queensland Harvest Strategy Policy, rebuilding strategies are required for stocks below 20% biomass. The first preference is to rebuild the stock with restricted targeted fishing, providing it can be achieved within a specified timeframe. However, if this cannot be achieved, fishing for the affected species may be ceased for a period.

The Gulf of Carpentaria inshore fishery working group has been formed to provide advice on the operational aspects of the management of the fishery in the Gulf of Carpentaria inshore fishery. The working group includes representatives from commercial, recreational and charter sectors; seafood processors and wholesalers, Indigenous representatives and the conservation sector.

Read more information on the working group.

The working group will have its first meeting in early 2022. The working group will:

  • review and provide advice on the fishery management framework, including management and reform options and fishing rules
  • develop a harvest strategy for this fishery consistent with the principles of the Queensland Harvest Strategy Policy and the Sustainable Fisheries Strategy 2017-2027.

Broad public consultation is planned for 2022 to allow all stakeholders, including commercial, recreational, charter and traditional fishers, environmental groups and other interested stakeholders, to provide comments to inform a final decision on management action to rebuild this important fishery.

More information

Access the Stock assessment of king threadfin in Queensland report, review and response to the review.