Evidence-based fisheries management relies on the availability of objective and reliable data. Catch rates are rarely validated and can be influenced by factors such as fishing power changes and hyper-stability. This makes traditional metrics, like annual harvest and catch rates less reliable for assessing stock status. Biological parameters offer critical insights for monitoring sustainability. Fishery-dependent programs can collect biological data efficiently and effectively but how is this possible when the catching and packing happens can be over 600 km and point of sale can be 2,000 km in a straight line from Fisheries Queensland’s researchers based in Cairns and Brisbane?
For 25 years, Fisheries Queensland has partnered with commercial fishers and processors in the Gulf of Carpentaria to collect biological data on their commercial harvest. A "choose-your-own-adventure" approach is employed to source measurements and samples at various stages, including at point of capture, during filleting, product transfer, packing, and at point of sale. The determining factors are what is possible and most suitable for the data provider (fisher or fish processor).
Applying this flexible approach has proved successful. Between 2000 and 2024, 39,849 barramundi were measured, and 13,204 otoliths aged. From 2016 to 2024, 9,533 king threadfin were measured, with 3,746 aged. In 2024, the inaugural year of grey mackerel sampling, 1,959 were measured, and 598 aged.
Measuring fish size, determining sex, and collecting otoliths for age estimation are the backbones of the program. These data are used to derive length-frequency distributions, growth patterns, maximum size and age, sex-specific differences or sex reversal size or age, age frequencies, year-class-strength, growth parameters and recommend sample size. Opportunities are leveraged to collect fishery intel to add context to the results and collect samples for research partners (e.g. genetic and reproduction).
Despite the challenges of remote areas and voluntary participation this ongoing time series provides invaluable insights into stock dynamics, including fecundity predictions, fishing selectivity, and stock biomass estimation. This collaborative effort underscores the importance of flexibility, innovation and partnership in addressing the challenges of monitoring in remote locations like the Gulf of Carpentaria.