Fish Stock Assessment Report

Overview

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 38 stock assessments during the fourth quarter of fiscal year 2024 (July 1, 2024 – September 30, 2024). That includes 11 assessments of FSSI stocks and 27 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: FY24 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:

1. Data-limited
2. Index-based
3. Aggregate biomass dynamics
4. Virtual population dynamics
5. Statistical catch-at-length
6. 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.

Proportion of each model type used in operational stock assessments and stock monitoring analyses of FSSI and non-FSSI stocks completed in fiscal year 2024.

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):

1. 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.
2. 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.
3. 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.

Proportion of stock assessment types for FSSI and non-FSSI stocks completed in fiscal year 2024.

Stock Assessment Program Performance

NOAA Fisheries monitors the performance of its stock assessment enterprise and transitioned to a new tracking measure in fiscal year 2024. Its old measure tracked performance as the percentage of FSSI stocks with “adequate stock assessments.” It considered only FSSI stocks, and tracked the proportion of them that obtained estimates of total stock abundance from stock assessment models within the last five years.

Its new measure is the Fish Stock Assessment Target Index (FSATI) and it increases the scope and specificity of performance tracking for the stock assessment enterprise. The FSATI considers all FSSI and non-FSSI stocks when tracking performance and measures their frequency and data input levels against stock-specific goals that are established and maintained by the appropriate Fisheries Management Council (FMC).

Frequency Scores

Stock frequency targets range between one and 10 and are set as recommended number of years between operational stock assessments. Stocks with lower frequency targets require more frequent assessments and typically include stocks with higher social, economic, or cultural value or those in poor condition (overfished or subject to overfishing). Stocks with higher frequency targets typically include those with minimal, if any, directed harvest.

Frequency scores range between zero and three points. Stock receive a full three points when operational stock assessments are completed at rate that matches or exceeds their target frequency. Stocks receive fewer points if they exceed their target frequency and become overdue. Stocks exceeding their frequency target by 50% or less receive two points, stocks exceeding it by between 50% and 100% receive one point, stocks exceeding it by between 100% and 150% receive half a point, and those exceeding it by more than 150% receive no points. In addition, stocks more than 10 years old automatically receive no points, regardless of their frequency target.

Current frequency score for all FSSI and non-FSSI stocks.

Data Input Scores

NOAA Fisheries tracks stock assessment data inputs across five categories: abundance, catch, composition, life history, and ecosystem considerations. Each category has six data levels within it that range from zero (no information used) to five (comprehensive information used). Their specific definitions are available in the 2018 Next Generation Stock Assessment Improvement Plan.

Stocks receive up to one performance point for each data category, for a total of five points across all data categories. Stocks receive a full point for each data category where data inputs meet or exceed their target, they receive half a point for each data category where data inputs are one level below their target, and they receive no points for data categories where data inputs are two or more levels below their target.

Current data input levels compared to data target levels for all FSSI and Non-FSSI stocks. Data levels for stocks with operational stock assessments that are 10 or more years old are reported as “Expired” because they are no longer valued for performance tracking purposes.

Fish Stock Assessment Target Index

The Fish Stock Assessment Target Index (FSATI) is a composite index calculated from the assessment frequency and data input scores of all FSSI and Non-FSSI stocks. The index value ranges between zero and 1,500. FSSI stocks receive increased consideration in the index relative to Non-FSSI stocks, with two thirds of index points based upon the attainment of FSSI stocks and one third based upon Non-FSSI stocks’ attainment.

Individual stocks receive between zero and eight points, meaning that there are 1,400 points attainable across all 175 FSSI stocks and 3,144 points available across all 393 Non-FSSI stocks. To calculate the current value of the FSATI, the ratio of points attained to attainable points for FSSI and Non-FSSI stocks is multiplied by the respective number of index points (1,000 points for FSSI stocks and 500 points for Non-FSSI stocks) to get a current index attainment value. The FSATI is generally reported out as the percentage of attained index points. The FSATI score for quarter 4 of fiscal year 2024 is 49.5%.

The number of FSSI stock assessments completed by NOAA Fisheries annually between fiscal years 2010 and 2023 (blue bars) and the total number of planned and completed operational stock assessments for fiscal year 2024 (green bar) and 2025 broken out by quarter (stacked, pattern bars). The old performance index of FSSI stocks with adequate assessments is shown as the solid red line (diamond data points), and FSATI attainment is shown as a blue line (circle data points). Fiscal year 2025 FSATI estimates are preliminary. Click here to download a table listing the most recent assessment information and performance level all FSSI stocks.

Click here to download a table listing the most recent assessment information and performance level for all non-FSSI stocks.

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:

Alaska Fisheries Science Center

Northwest Fisheries Science Center (West Coast)

Southwest Fisheries Science Center (West Coast)

Pacific Islands Fisheries Science Center

Northeast Fisheries Science Center (Greater Atlantic)

Southeast Fisheries Science Center