Usage and Scope of CWT

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Many State, Federal, Tribal and private reporting agencies in the United States and Canada participate in a massive coastwide coded wire tagging effort to provide essential data for effective conservation and management of Pacific salmonid stocks.  This information provides the basis for monitoring the fisheries, allocating harvest rights among competing domestic users, improving productivity of hatchery stocks, establishing escapement goals, and satisfying Tribal treaty obligations.  These data also play a key role in the U.S. - Canada Salmon Treaty allocations and management of transboundary stocks.

Over 50 million juvenile salmon and steelhead are now tagged annually.  Chinook tagging levels are the highest (~ 40 million), followed by coho (~ 9 million).  The remaining species including steelhead, chum, pink, and sockeye salmon tagging levels comprise ~ 1.0 million tags.

This massive tagging effort represents approximately 1,200 new tag codes each year.  Hundreds of separate studies are involved, many of which include replicate groups as part of the basic design.  Total cost is in excess of 7.5 million dollars annually.  The cost per individual fish ranges between 12 and 15 cents, depending on local labor costs, logistics of tagging, and number of tags purchased for a given code.

Mass marking involves marking hatchery fish to enable them to be visually identified.  This is usually done by removing the adipose fin from hatchery reared salmonid fish to differentiate them from wild or naturally produced fish.  This enables the administration of mark-selective fisheries, in which only hatchery reared fish bearing the adipose fin clip are retained, and unmarked (presumably wild) fish, if caught, are released.  The management goal of mark-selective fisheries is to reduce the harvest of naturally produced fish and therefore conserve wild fish populations.

An additional 9-10 million dollars is expended annually coastwide for tag recovery programs in U.S. and Canadian commercial and recreational fisheries.  Tag recoveries from returning adult fish are on the order of 300,000 per year.

Salmon and steelhead feed in the ocean from one to five years, depending on the species, before returning to spawn in their natural streams.  Consequently, many millions of tagged fish from a number of brood years are present in the Pacific Ocean at any given time.  As such, the multiplicity of tagging studies today represent a long term, multi-million dollar investment by State, Federal, Tribal, and private sector entities.