Fish Stock Assessment Report
Quarterly summary of the activities of the national stock assessment enterprise.
NOAA Fisheries uses stock assessments to monitor the condition of over 500 fish stocks and stock complexes (groups of similar stocks managed together). Stock assessments are scientific efforts that involve data collection, data processing, and mathematical modeling to estimate the health and size of a fish stock, measure how fishing affects the stock, and project harvest levels that achieve the largest sustainable long-term yield. This page provides an annual report, broken out by fiscal year (October 1 – September 30) and quarter, detailing NOAA Fisheries’ planned and completed stock assessments. Previous years’ reports are stored in our archive.
Stock assessments provide the scientific foundation of sustainable fisheries management. Fishery managers use the results of assessments to evaluate the status of fish stocks and set annual catch limits (ACLs). An ACL is the largest amount of fish that commercial and recreational fisheries can sustainably harvest from a stock in one year. ACLs help prevent overfishing from occurring and help fishers to catch the maximum number of fish over the long-term. NOAA Fisheries works with its partners in each management area to conduct stock assessments, but cannot assess all managed stocks each year. Each region rotates the stocks it assesses based upon the availability of data, the complexity of available data, the structure and diversity of local fisheries, its available resources, and its processes for scheduling, conducting, and using stock assessment results in management.
NOAA Fisheries sorts stocks into two general categories for tracking and reporting purposes. It tracks the stocks with higher levels of commercial, recreational, or ecological value as components of the Fish Stock Sustainability Index (FSSI). NOAA Fisheries prioritizes FSSI stocks for assessments that make use of the most advanced analysis techniques when available. NOAA Fisheries also conducts stock assessments for many stocks not on the FSSI list (non-FSSI stocks) to provide necessary management advice.
Completed and Planned Assessments
NOAA Fisheries completed 62 stock assessments during the fourth quarter of fiscal year 2023 (July 1, 2023 – September 30, 2023). That total includes 28 assessments of FSSI stocks and 34 assessments of non-FSSI stocks. The tables below show the regional breakdown of this year’s planned and completed FSSI (Table 1) and non-FSSI (Table 2) stock assessments.
Table 1: FY23 Planned and Completed FSSI Stock Assessments
Stock Assessment Model and Type
NOAA Fisheries categorizes stock assessments based upon the data used, the structure of the model, the effort required to complete the assessments, and the final products.
Stock Assessment Models
Stock assessment models evaluate important aspects of fish biology that shape a stock’s current and future condition:
- Abundance – The total amount of fish in a stock, over time
- Reproduction & Growth – The amount of fish and biomass added to a stock each year
- Mortality – The number of fish that die due to natural or man-made causes (e.g., fishing) each year
NOAA Fisheries uses a variety of models to conduct stock assessments. When stock assessment scientists conduct an assessment they identify and develop appropriate models based upon the available data. Those models fit into one of six general categories based upon their data requirements and products:
- Aggregate biomass dynamics
- Virtual population dynamics
- Statistical catch-at-length
- Statistical catch-at-age
Data-limited and index-based methods are the most basic model types used by NOAA Fisheries. They provide simplified catch advice when stock-level data are limited. Data requirements for these methods include the total catch of a stock over time or a survey-based index of total stock abundance. NOAA Fisheries has some level of catch data available for the majority of the stocks it assesses.
The remaining modeling methods are more complex and require additional data such as the length composition (number of fish at each length category) or age composition (number of fish at each age) of a stock. These models incorporate more data and utilize advanced statistical techniques to optimize advice provided to fishery managers, including the determination of whether or not a stock is undergoing overfishing, approaching an overfished state (likely to become overfished in the next two years), or is already overfished and below a healthy level, as well as the selection of harvest targets and control rules.
Stock assessment results can only be used in management after reviewers have evaluated the appropriateness of the methods and data used. When a stock assessment successfully completes review, it is certified as the “best scientific information available”. Occasionally, a stock assessment will fail review, meaning the results are rejected and not suitable for use in fisheries management.
Stock Assessment Types
Stock assessments are scientific processes that analyze available data using statistical models to produce management advice. Assessment results estimate sustainable harvest levels maximizing fishery removals while protecting stocks’ long-term health. Data-limited and index-based models provide advice based upon the analysis of observed trends in catch data or fishery-independent survey data. More advanced models evaluate the current condition of a stock and develop projections that estimate a stock’s future condition. Managers routinely use those projections to update harvest guidance in the years between stock assessments.
Each NOAA Fisheries region updates its portfolio of stock assessment activities annually based upon local priorities and available resources. Those activities fall into one of three general stock assessment types (Figure 3):
- Research Stock Assessments – Efforts that develop or substantially revise a stock assessment data type, method, or stock-specific model. Research stock assessments undergo comprehensive, independent reviews and do not explicitly provide management advice. Activities that substantially update an assessment model and provide management advice are considered both a research assessment and an operational stock assessment.
- Operational Stock Assessments -- Analyses conducted to provide routine scientific advice to fishery managers. These are NOAA Fisheries’ principal assessment-related activities and include first-time uses of newly developed assessment models and efforts that update existing models with the most recent data and potentially include minor modeling method adjustments. At minimum, operational stock assessments make ACL recommendations. Those with more complex models also inform decisions related to stock status.
- Stock Monitoring Updates – Activities that provide stock management advice to fishery managers between operational stock assessments. These analyses involve re-running the latest model (completed during an operational stock assessment) and/or projection with updated catch information to develop new catch advice.
Stock Assessment Program Performance
NOAA Fisheries monitors the performance of its stock assessment enterprise. One major measure of performance is the percentage of FSSI stocks with “adequate” stock assessments. Adequate stock assessments are defined as stock assessments that:
- Provide a model-derived estimate of total stock abundance, and
- Were completed within the last five years
Archive and More Information
To view current and historical records of stock assessments please visit our Stock Status, Management, Assessment, and Resources Trends (Stock SMART) tool.
To view reports on NOAA Fisheries’ stock assessment activities from previous years please visit our reports archive.
To view information on NOAA Fisheries' scientific surveys please visit our research surveys page.
To view information specific to a particular region or science center, please visit its web page:
Northwest Fisheries Science Center (West Coast)
Southwest Fisheries Science Center (West Coast)
Northeast Fisheries Science Center (Greater Atlantic)