Saucer scallop stock assessment

Chart of Queensland stock assessment biomass estimates and key management actions for saucer scallop

The chart presents the biomass ratio of Ballot’s saucer scallop from 1956 to 2022. The ratio is relative to 1 in 1956. The biomass ratio declined between 1956 and 2016 to 10% unfished biomass, after increasing to 18% in 2018, the biomass ratio in 2022 was estimated at 15%. Data used in the stock assessment includes 67 years of commercial catch data, 392,736 scallops measured and 10 years of survey density data. The various management measures that have been implemented over time are detailed. Before 1987, minimum legal size limits were less than 9cm and since 1987 seasonal minimum legal size limits of 9cm and 9.5cm were applied. Since 1997 spatial closures have applied, including rotational closures from 2001 to 2016 and the current permanent closures. As of November 2021 there is no take of scallops in the southern inshore and central trawl regions.

Chart of estimated retained catch for Queensland saucer scallop from 1956 to 2022

: The chart presents the Ballot’s saucer scallop retained catch taken by commercial fishers from 1956 to 2022. The commercial harvest is from a historical source between 1956 and 1988 and from the logbook program between 1987 and 2022. Before 2022, retained catch estimates from the logbook were greater than 700 tonnes of meat weight per fishing year, and peaked in 1993 at over 1800 tonnes. Since 2011, retained catch estimates were less than 400 tonnes per fishing year.

Why did we assess the Ballot’s saucer scallop stock?

In 2022, Fisheries Queensland completed the fifth stock assessment of Queensland Ballot’s saucer scallop. It used the most current commercial catch and survey data to:

determine the sustainability of the stock
help inform management decisions.

This assessment estimated that the saucer scallop stock level was 15% of unfished biomass with a 95% confidence interval between 10% and 25%.

How was the stock assessment conducted?

The 2023 assessment used an age-structured population model with a monthly time step. The model was based on the methodology from the 2018 assessment.

Next steps for fishery management

Under the Queensland’s Sustainable Fisheries Strategy 2017–2027, 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 stop for a period.

The trawl fishery working group provides advice on the operational aspects of the management of the fishery. The working group includes representatives from commercial and recreational fishing sectors, seafood processors and wholesalers, and the conservation and environment sectors.

Read information on the working group.

More information

Access the Stock assessment of Ballot’s saucer scallops (Ylistrum balloti) in Queensland, Australia, with data to October 2022.

Last updated: 25 Aug 2023