Fisheries science: Overview

Fisheries science: Data to decision

Fisheries science brings together ecology, mathematics and statistics, population dynamics, and marine biology to better understand fish stocks and fisheries so that they can be sustainably managed.

Under the Fisheries Act, “fish” also includes other species such as shellfish, crustaceans, and marine mammals.

An infographic depicting the Data to Decision process which includes data collection, stock assessment, science advice, and fisheries management decisions. Data to decision: How fisheries science informs and contributes to sustainable fisheries management. Data Collection: Data can be fishery dependent (e.g. from industry fishing activities), or fishery independent (e.g. from targeted surveys). Output: Indicators of abundance, biological information, catch from multiple sources (commercial, recreational, Food, Social and Ceremonial). Stock assessment: Data are analyzed using statistical methods and mathematical models to learn more about the fish stock. Output: Estimates of the Limit Reference Points, stock status, evaluation of harvest control rules. Science advice: Science advice is peer-reviewed through DFO's Canadian Science Advisory Secretariat. Output: Science Advisory Reports, projections of potential future stock status under different catch levels. — Infographic 1: Data to decision.

Video: Data to Decision of Fisheries Science

Fisheries and Oceans Canada is responsible for fisheries science and fisheries management in Canada. Fisheries management decisions are informed using the Data to Decision process which is made up of four steps:

Step 1: Data collection. Information about a fish stock, such as length, weight, age, and average catch.

Step 2: Stock assessment. Analyzes the collected data to learn more about a fish stock. This helps us understand:

the estimated stock abundance
the estimated level of fishing pressure on the stock
effects of environmental conditions on the stock
how potential decisions or events might affect those stocks

Step 3: Science advice. Advice based on the stock assessment analysis or other scientific information. This advice can include estimates of stock abundance, life history information such as growth or maturity, and information on environmental conditions affecting the stock.

Step 4: Fishery management decision. This sets out the management measures for a specific fishing season. It can include opening and closing dates, size restrictions, and Total Allowable Catch or quota. Over the longer-term, science advice also informs the development of fisheries management planning documents, like Integrated Fisheries Management Plans and Rebuilding Plans.

In addition to science advice, the Minister of Fisheries and Oceans also considers information provided by other groups, such as industry, Indigenous communities and coastal communities to make fishery management decisions.

Fish stocks

Fish stocks are not the same as fish populations. A population is a group of fish of the same species that reproduce together, but a fish stock can be a population, a smaller subset of one population or can include more than one population. Fish stocks are often identified by management area, which are defined, geographical regions. When we assess a fish stock, we are estimating how many fish are in a management area in a given period, as well as the expected impacts and benefits of proposed fisheries management measures for that stock. They are typically fish of the same species. Individual fish in different stocks might mix or migrate between different areas.

Information from stock assessments help us make decisions about management measures for a given fish stock. Management measures are rules or directions to follow for specific management areas or fisheries.

Stock vs population

A population of Atlantic Mackerel can be found along the coast from Labrador to North Carolina. However, the Atlantic Mackerel stock managed by Fisheries and Oceans Canada only includes the fish found in parts of Canadian waters from Labrador to Nova Scotia.

Taking a precautionary approach

The Sustainable Fisheries Framework establishes a precautionary approach to fisheries management. A precautionary approach means:

being cautious with decisions when scientific information is uncertain
not using the absence of adequate scientific information as a reason to postpone or fail to take action to avoid serious harm to the resource

Fisheries science is one source of information that helps us implement the different parts of the fishery decision-making framework incorporating the precautionary approach. Fisheries science includes establishing or providing advice on:

reference points
stock status
evaluation of harvest decision rules
consideration of uncertainty and risk

Together, these help to inform management decisions for a stock.

Reference points

Reference points are used as benchmarks to evaluate the biomass (a measure of fisheries abundance) or harvest rate for a stock. Reference points can represent the following for biomass or harvest rate:

targets and thresholds – to achieve desired states for the stock and fishery
limits – to avoid undesired states where the stock is at increased risk of serious harm

Targets, thresholds, and limit reference points can be used to compare the status of a stock relative to conservation and other fishery objectives, and to provide advice on the likelihood of which management measures could meet those objectives.

Stock status

Stock assessments can be used to estimate where stock abundance or biomass is in relation to:

limits
targets
the three stock status zones
- critical
- cautious
- healthy

This is important to keep track of how stock abundance or biomass changes over time.

More information about reference points can be found in A Fishery Decision-making Framework Incorporating the Precautionary Approach. More information on the current status of fish stocks is available on the Sustainability Survey for Fisheries webpage.

Evaluation of harvest strategies with harvest decision rules

A harvest strategy is the approach to managing the harvest of a stock. Key components of a harvest strategy include

pre-agreed harvest decision rules
management actions for each stock status zone

We provide advice to help evaluate harvest decision rules to see if they will help to achieve conservation and other fishery objectives. This can be done:

before they are put into practice using simulations of how the stock might respond to different management measures, and/or
after they have been in use for some time to check how well they are working.

Consideration of uncertainty and risk

Scientific uncertainty is present in all steps of the Data to Decision process, as well as in the implementation of a harvest strategy or management approach. Whenever possible, scientific uncertainty is taken into account within the stock assessment and science advice.

Fisheries science also provides advice on the potential consequences or risks of different options for management measures, and how likely the options are to achieve objectives. The results of these evaluations help inform evidence-based decision making to promote sustainable fisheries.

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