Fish Stock Sustainability

Fish Stock Sustainability Index

The Fish Stock Sustainability Index is a quarterly index that measures the performance of U.S. federal fisheries. Currently, the index includes 175 fish stocks selected for their importance to commercial and recreational fisheries. These 175 stocks represent over 80 percent of total U.S. fishing catch.

The index score increases when NOAA Fisheries determines the status of a stock and when a stock's status improves (either no longer subject to overfishing, no longer overfished, and stock size increases to at least 80 percent of target or is rebuilt).

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Index Scoring Methodology

Each quarter, NOAA Fisheries calculates an Fish Stock Sustainability Index score, incorporating information from new stock assessments and stock status determinations. The index is calculated on a 1,000 point scale using the following methodology:

Step 1: Assign weighted criteria points for each stock based on the following:

* Stocks rebuilding from a previously overfished condition are not awarded the fourth point until they reach Biomass Maximum Sustainable Yield, as mandated by the Magnuson-Stevens Act. After they have been fully rebuilt, they may fluctuate within the 80% parameter and retain the score of 4 like the other non-rebuilding stocks. This point is in addition to the point awarded for being above the “overfished” level.

Step 2: Calculate the sum of criteria points for all index stocks.

Step 3: Calculate maximum criteria points possible: multiply number of index stocks (175) x maximum criteria points per stock (4 points).

Step 4: Calculate a raw total point score: divide sum of criteria points / maximum criteria points possible.

Step 5: Convert raw total point score to a 1,000 point scale: total raw point score*1,000.

History of the FSSI

Developed in 2005, the first index reported on 230 stocks managed under federal fishery management plans, including domestic stocks we manage solely within the U.S. Exclusive Economic Zone and international stocks we manage jointly under international agreements. The first version of the index had a maximum of 920 possible points. In 2015, we introduced index version 2.0. We removed international stocks from the index to better reflect U.S. fishery management performance. This resulted in 199 stocks and a revised maximum possible score of 1,000 points.

In 2020, to make sure the index continues to focus on the most important commercial and recreational stocks, we revised the list of stocks to 175 in version 3.0.

NOAA Fisheries tracks the status of all international and domestic stocks contained in federal Fishery Management Plans whether or not they meet criteria for inclusion in the index. By focusing on domestically important stocks, the index is a stronger performance measure of U.S. fishery management. 

Read the historical summary (PDF, 9 pages) of all the index stocks over time. 

Status Determinations

The Magnuson-Stevens Fishery Conservation and Management Act requires that a fishery management plan specify objective and measurable criteria, or reference points, for determining when a stock is subject to overfishing or overfished. A scientific analysis of the abundance and composition of a fish stock (stock assessment) evaluates the stock against its reference points.

Stock assessments use the best information available, which may include data from fishery landings, scientific surveys, and biological and ecological studies. A stock assessment typically undergoes peer review by independent scientists before it is accepted as the best scientific information available.

Generally, NOAA Fisheries uses the stock assessment and the reference points to determine whether the stock is subject to overfishing or overfished. Information from the stock assessment is used by the regional fishery management council to recommend the annual catch limit for the stock.

NOAA Fisheries’ stock assessments are key to sustainable fisheries management. A number of NOAA Fisheries resources can help you learn more. 

• Learn more about the science behind stock assessments.

Rebuilding Plans

When NOAA Fisheries determines that a stock is overfished, the relevant regional fishery management council (council) must implement a plan to rebuild it to the level that can support maximum sustainable yield (MSY). A typical rebuilding plan allows fishing to continue, but at a reduced level so that the stock will increase to the target level that supports MSY.

The graph below helps illustrate the concept of a rebuilding stock. A stock that is declared overfished—with a population size below the blue line—must have a rebuilding plan in place. The goal of that plan is to grow the stock to its target size—the orange line. The time between when the rebuilding plan goes in place and reaching the orange line is the stock’s rebuilding period. The time to achieve a rebuilt status will vary, depending on the individual stock.

 

For questions or concerns on this topic, please contact Karen E. Greene.