A coded wire tag (CWT) is a small piece of stainless steel wire about 1 millimeter long. It is usually inserted into the snout of a juvenile salmonid before it is released from a fish hatchery or juvenile fish trap. A coded wire tag contains a unique code that identifies an individual or group of fish that were released at the same place and time. Hundreds or thousands of juvenile fish in the same group can be inserted with a coded wire tag that has the same code.
When adult salmon or steelhead are caught, return to a hatchery, or return to rivers to spawn, the coded wire tag is recovered with the aid of a coded wire tag detector, which is a device similar to a metal detector. If a coded wire tag is detected, the snout of the fish is sent to a lab for processing.
Coded wire tags are used coast-wide by various agencies to help assess salmonid abundance and catch rates on certain populations of salmon and steelhead. The Washington Department of Fish and Wildlife (WDFW) collects and stores the data that comes from recovered coded wire tags. The coded wire tag data, along with catch and sample data, is eventually submitted to a coast-wide database, the Regional Mark Information System (RMIS). Other agencies from Alaska, British Columbia, Oregon, Idaho, California, Treaty Tribes, and the U.S. all submit coded wire tag information to this important data system. RMIS data is used to inform and administer the terms of the Pacific Salmon Treaty between the U.S. and Canada.
More information about coded wire tags can be found at the following links:
- Regional Mark Processing Center: This is the home page for the RMIS coast-wide database.
- Pacific Salmon Commission: The governing body for administering the terms of the Pacific Salmon Treaty between the U.S. and Canada.
- WDFW-Coded Wire Tag Fish Recoveries: WDFW’s coded wire tag recoveries database output hosted by data.wa.gov and refreshed nightly.
The Coded Wire Tag lookup tool on this page can be used by sport fishers to look up the release information for fish that had a CWT detected by a sport creel sampler. You must know the exact sample number that is provided by the sampler and enter that number into the tool. Example: CWT00012345.
WDFW Coded wire tag lookup
Visit data.wa.gov to view or download the complete Coded Wire Tag Fish Recovery dataset.