Determining the Status of Fish Stocks in Data-Poor Environments and Multispecies Fisheries

This policy brief examines methods for assessing fish stock status in data-poor and multispecies fisheries to inform World Trade Organization (WTO) negotiations on fishing subsidies. It highlights that over 80% of global catches occur in fisheries lacking the data for conventional model-based assessments and proposes the use of data-limited methods, empirical indicators, and adaptive management frameworks like FISHE to identify overfished stocks and trigger subsidy prohibitions.

• A significant majority of global fish catches, exceeding 80%, are from fisheries that lack the infrastructure, resources, and data required to perform quantitative model-based stock assessments to estimate fishing mortality and biomass relative to reference points.
• Conventional stock assessment methods are often unsuitable for tropical fisheries because these fisheries are frequently multispecies, multi-gear, and data-limited, and the models often fail to account for ecosystem interactions.
• In data-poor environments, managers can use empirical indicators—which are measured directly from monitoring data—or model-derived indicators. Examples of empirical indicators include catch per unit effort (CPUE), mean length of fish in the catch, and catch levels.
• The Framework for Integrated Stock and Habitat Evaluation (FISHE) provides an 11-step adaptive management process for data-limited conditions. It allows for the use of 'hidden' data (data collected for non-management purposes, such as reef health surveys) and Productivity-Susceptibility Analysis (PSA) based on expert and fisher knowledge when no formal data exists.
• Multispecies fisheries face the risk of 'serial depletion,' where individual stocks are depleted sequentially. FISHE manages this by organizing species into 'baskets' or 'tiers' and using a representative species from each group to determine if the target species are overfished.
• For WTO fisheries subsidy negotiations, the brief suggests that using 'alternative reference points' beyond Maximum Sustainable Yield (MSY) would provide governments with the flexibility to apply subsidy prohibitions based on the specific data available in their fisheries, such as proxies for reference points or local fishers' knowledge.

APA

Headley, M. (2020). Determining the Status of Fish Stocks in Data-Poor Environments and Multispecies Fisheries. International Institute for Sustainable Development. https://www.iisd.org/system/files/publications/fish-stocks-multispecies-fisheries.pdf

Chicago

Headley, Maren. Determining the Status of Fish Stocks in Data-Poor Environments and Multispecies Fisheries. International Institute for Sustainable Development, 2020. https://www.iisd.org/system/files/publications/fish-stocks-multispecies-fisheries.pdf.

Wikipedia

{{cite report |last1=Headley |first1=Maren |title=Determining the Status of Fish Stocks in Data-Poor Environments and Multispecies Fisheries |publisher=International Institute for Sustainable Development |date=June 2020 |url=https://www.iisd.org/system/files/publications/fish-stocks-multispecies-fisheries.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{headley2020determining, author = {Headley, Maren}, title = {{Determining the Status of Fish Stocks in Data-Poor Environments and Multispecies Fisheries}}, institution = {International Institute for Sustainable Development}, year = {2020}, month = jun, url = {https://www.iisd.org/system/files/publications/fish-stocks-multispecies-fisheries.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }