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Coded wire tagging program

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What is the coded wire tagging program

The Coded Wire Tag (CWT) Program guides the chinook and coho salmon fisheries along the west coast, and is one aspect of Canada’s obligations under the Pacific Salmon Treaty with the United States. The program’s activities aim to rebuild vulnerable salmon stocks and provide harvest opportunities. It includes tagging juvenile fish, collecting heads from fisheries and escapement, dissecting heads to recover CWTs, and providing CWT information for stock assessment and management decisions. The program is one of the largest animal tagging programs in history, and it has been running every year since the 1970s.

Coded wire tags are tiny lengths of metal wire inscribed with a numeric code that are inserted in the snout of some juvenile salmon before they make their way to the ocean. Every year, approximately 50 million juvenile salmon are tagged in Canada and the US. Tags can be recovered when returning fish are caught. This provides important information about their origin, age, growth, run timing, and other characteristics. Data from these tags are critically important to guide the sustainable salmon fisheries along the west coast.

How you can participate

Coded wire tagging program data helps target management

Good management decisions require good information. High-quality CWT data reduce uncertainty and allow for maximum fishing opportunities and the implementation of conservation measures to be targeted to those places that need them most. Reliable information requires high levels of participation in the Salmon Head Recovery Program.

Scientists and biologists use information from CWTs to learn about fish origins, age, and run timing. This information is combined with catch and effort data used to guide sustainable fisheries. Information from CWTs helps managers to target management measures only in areas and time periods that need it, while keeping fishing opportunities open in areas and periods that don’t.

How the coded wire tagging program works

Each year CWTs are applied to hundreds of stocks of juvenile chinook and coho that are released to begin their ocean migration. Each group of fish is assigned a unique code that links to release information such as where and when the fish were released, how many were tagged and all the associated rearing information. Hatcheries externally "mark" their fish by clipping the adipose fin to distinguish them from wild fish and that a CWT may be present. As the fish mature, all fisheries encountering these tagged stocks and the rivers where these tagged stocks spawn are sampled for CWTs. Heads are removed from the fish and dissected in labs where the recovered CWTs are read and data-entered along with supporting catch information. Because CWTs are so small, electronic tag detection and magnification is required to remove and read each tag. Combining recovery data with the release data results in stock-specific information about abundance, distribution and survival. These data are used to make science-based stock assessment and fishery management decisions, as well as negotiating catch allocation between the two countries. All of these data are shared between Canada and the US.

With sufficient CWT recoveries and good quality catch estimates a "picture" emerges of where, when and by how much individual stocks are being harvested and what percentages are surviving to spawn. As more CWTs are recovered the information becomes more reliable allowing for more appropriate and targeted conservation measures.

Because CWTs are applied every year, management decisions, hatchery rearing methods, alternative stock identification and ageing techniques can all be assessed and improved using CWT data. As climate changes and fisheries evolve, having a longstanding tool is very useful for identifying changes in migration patterns, timing, and the abundance of stocks along the entire west coast from California to Alaska.

Head collections

The tags stay in place as fish grow and are recovered after they are caught in fisheries. Heads are removed and sent to a centralized lab for dissection.

This program depends on you

CWTs are recovered from heads of adipose fin-clipped fish that are voluntarily submitted by fishers through head collection programs. This means the program relies on participation from fishers like yourself.

We need more heads

The CWT Program is 'only as good as the data', and is most effective when many tags are recovered. CWTs are often rare in catch and not every marked fish will have a tag. This means the program needs to recover as many heads as possible so that more tags are found. By participating, you are helping to improve scientific advice for salmon management and helping to preserve local fishing opportunities that might be reduced without these data.

If you are unsure of how to participate or have questions about the program, please contact us at 1-866-483-9994.

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