Quantitative Stock Assessment in Fisheries Management

Quantitative stock assessment underpins modern fisheries management by estimating the abundance and productivity of fish populations and forecasting their response to different levels of fishing pressure. These assessments combine catch records, survey indices, life-history traits and environmental covariates within mathematical and statistical models to derive key reference points such as maximum sustainable yield (MSY), fishing mortality at MSY (FMSY) and biomass at MSY (BMSY). In data-rich contexts, age-structured models assimilate detailed catch-at-age and effort data, whereas data-limited stocks often rely on simpler surplus-production or catch-only approaches calibrated by priors on growth rates and resilience. By quantifying uncertainty through sensitivity analyses or closed-loop simulation (management strategy evaluation), managers can appraise trade-offs between yield, risk of overfishing and rebuilding time. Advances in computation and open-source software now allow rapid testing of harvest control rules, ensemble modelling of multiple assessment methods and explicit treatment of process and observation error. Globally, quantitative assessments inform quotas, spatial closures and rebuilding plans, providing a scientific basis for sustainable exploitation that balances food security, economic livelihoods and ecosystem conservation.

Research from Nature Portfolio

Recent studies have applied simulation-based frameworks to evaluate the performance of catch-only methods under varying fishing scenarios for data-limited stocks. One investigation focused on European anchovy in northwest African waters, comparing five catch-only models against a true life-history reference. All models tended to underestimate biomass relative to BMSY, especially under constant fishing mortality, but a state-space catch-only model demonstrated greater resilience in recovering overfished status. The work highlights the need for methodological benchmarking via simulation and the potential of state-space formulations to improve robustness of single-species assessments in regions lacking comprehensive data.

Quantitative Stock Assessment in Fisheries Management publication trend

The graph below shows the total number of articles in quantitative stock assessment in fisheries management across all publications each year (not limited to Nature Index journals).

Technical terms

Maximum sustainable yield (MSY): The largest long-term average catch that can be taken from a stock under prevailing environmental and fishing conditions without impairing future productivity.

Catch-only methods (COMs): Assessment techniques that use historical catch time series and life-history information, but lack direct abundance indices, to infer stock status.

Surplus-production model: A population model that relates aggregate biomass growth to fishing removals, estimating key parameters such as intrinsic growth rate and carrying capacity.

Management Strategy Evaluation (MSE): A simulation framework that tests proposed harvest control rules under uncertainty by linking operating, estimation and implementation models in a closed-loop fashion.

State-space model: A statistical approach that separates observation error from process variability by modelling true stock dynamics and observed data as linked stochastic processes.

References

1. A simulation-based option to assess data-limited fisheries off West African waters. Scientific Reports (2023).
2. Method evaluation and risk assessment: A framework for evaluating management strategies for data‐limited fisheries. Fish and Fisheries (2023).
3. Assessment of Seabream Fisheries Stock of Oman Using the Monte Carlo Catch Maximum Sustainable Yield and the Bayesian Schaefer Model Methods. Sustainability (2023).
4. Status and rebuilding of European fisheries. Marine Policy (2018).