What is a fish stock?

A biological fish stock is a group of fish of the same species that live in the same geographic area and mix enough to breed with each other when mature. ‘Stock’ may also refer to a multispecies complex that is managed as a single unit.

Why do we assess stocks?

NOAA Fisheries’ stock assessments provide high-quality science information needed by managers to support sustainable fisheries as components of resilient ecosystems, communities, and economies. Assessments provide the scientific basis for determining if a stock is overfished or experiencing overfishing, calculating a sustainable harvest rate, and forecasting catches that correspond to that rate.

What is a stock assessment?

A stock assessment is the process of collecting, analyzing, and reporting demographic information to determine changes in the abundance of fish stocks in response to fishing and, to the extent possible, predict future trends of stock abundance.

What is an adequate assessment?

Assessments are considered adequate when they use modeling approaches that are able to address long-term population dynamics of the stock (i.e. assessment level of 3 or above according to the 2001 Marine Fisheries Stock Assessment Improvement Plan, have been updated within five years, and are recommended as best scientific information available through respective peer review processes. The definition of an adequate assessment will change as NOAA Fisheries finalizes and implements the new Stock Assessment Improvement Plan (draft expected in mid-FY16).

What data are used in stock assessments?

Stock assessments are based on models of fish populations that are calibrated by three primary categories of observational data: catch, abundance, and biology. Additional data, such as ecosystem and socioeconomics information, can also be included in assessments. Assessment data must be accurate and timely to ensure the highest quality stock assessments and the best scientific information for resource managers.

How is NOAA Fisheries working to improve data collection programs?

Good stock assessments require high quality data inputs. Here are some of the things NOAA is doing to ensure we continue to provide the best scientific information available to resource managers:

  • Expanding the use of electronic data collection and facilitating rapid access to data
  • Attaching advanced monitoring equipment to traditional sampling gear to collect environmental data concurrently during fish surveys
  • Conducting visual surveys in complex (i.e. non-trawlable) habitats using imaging systems on robotic and autonomous underwater vehicles (AUVs - click here to read more about AUVs from one of our Teachers at Sea)
  • Utilizing non-extractive methods for abundance sampling, such as hydroacoustic technology
  • Using electronic fish tags, genetic analyses, and research on the chemical composition of otoliths (fish ear bones) to better define stock boundaries, habitat use, and fish movements

What is ecosystem data?

Factors other than fishing can have an important role in determining the health and abundance of fish stocks. Ecosystem factors such as predator-prey interactions among species, changes in marine coastal habitat, and constantly changing ocean conditions may all influence fish stock dynamics. Examples of ecosystem data that may inform stock assessments include:

  • Time series of physical or environmental data (e.g., ocean temperatures, currents, etc.) that help scientists understand fluctuations in fish stocks and improve calibration of surveys that monitor stocks
  • Information on the effects of large-scale climate processes (e.g. El Niño) and climate change (Read more about the Fisheries and the Environment program)
  • Information on species habitat utilization, the quantity and quality of marine habitats, and the impacts of fishing on habitat (Read more about the Habitat Science program)
  • Predator-prey and other studies (e.g., toxins, parasites, diseases, etc.) that provide more accurate values for important stock assessment parameters such as natural mortality

Where can I find stock assessment results and more information pertaining to status of assessed stocks?

The Species Information System Public Portal provides access to the most up-to-date assessment results and status of stocks contained in the Fish Stock Sustainability Index (FSSI).

Why does the schedule of planned assessments change?

The schedule of planned assessments is provided by each region at the beginning of the fiscal year and updated as new information becomes available. Changes to the schedule may occur as the feasibility and time needed to conduct assessments are refined, and as assessment needs are updated in coordination with our regional and international partners. Changes in timelines are common for stocks previously unassessed or for assessments using innovative methods.