Coded Wire Tag Information
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. The coded wire tag (CWT) is widely used by fisheries agencies on the West Coast as a major information collection tool for stocks of salmon and steelhead (Oncorhynchus spp.).
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.
Resource management projects include hatchery contribution studies, differential treatment studies, fishery contribution studies, and a variety of other related studies which are important for fisheries management and research.
Coded-wire tags help inform the below management and research questions:
Management
(Basin-wide implications, on-going marking)
- How many fish survived to adults?
- Where do the fish go? Should they be there?
- When are they there?
- How many and where are fish caught?
- In a particular area where fish are caught, where did they come from?
- Who caught the fish and how many?
- Are enough of the right fish returning to reproduce the next generation?
- What is going to happen next year? Can we make changes to affect it?
- Over time, are these fish runs increasing or decreasing?
Hatchery Evaluation
(Site-specific, on-going marking)
- How many fish survive to adulthood?
- Where do they go?
- Who catches them?
- Where do they spawn?
- Are these fish fulfilling the reasons for which they were produced?
- Is the hatchery program effective at producing the quality (age, size, weight) and number of fish needed?
- Are these fish increasing or decreasing in numbers over time?
- Are population characteristics changing (age, size of adults, male/female ratio, number of jacks, etc.)
- What other fish are returning that don’t belong there?
Experimental Marking
(fixed time studies)
- Are fish being released at the right time?
- Are fish being released at the right place?
- Are fish getting the right diet?
- Are there better ways to control disease?
- Can we change things at the hatchery that:
- Result in more adult fish?
- Affect where the fish go?
- Are there better ways to mark fish?
- Is the right strain of fish being used?
Habitat Evaluation
- Does the habitat produce quality smolts and the number of adults needed?
- Over time, do habitat improvements result in more adult fish returning?
- What other fish are showing up in the habitat that do not belong there?
Wild Tagging
- Is it OK to use hatchery fish to evaluate a wild stock (specific locations)?
- Do wild fish behave differently?
- Do wild fish survive differently?
Publications
A subset of CWT publications are grouped by topics of higher interest to the RMCT and CWT users. Click the button to navigate to one of the topics.
All CWT related documents are also accessible in the document table at the bottom of this page as well as under the Resources section of this website.
Click the below buttons to navigate to Northwest Marine Technology, Inc and Pacific Salmon Commission external webpages that house CWT related documents.
Overview of Coded Wire Tag Program including Applications in Fisheries Management and Research
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.
The invention of micro-sized coded wire tags (up to 1.5 mm length) that could be easily implanted into the tough nasal cartilage of juvenile salmonids (see figure) greatly changed marking studies because of the numerous advantages over fin clipping.
- 1960’s, the first tags were developed and carried a dozen different colors and up to five longitudinal stripes allowing identification of different fish release groups.
- 1971, binary coded tags were by Northwest Marine Technology, Inc. which replaced the color coded tags. Binary tags had improved readability and large number of available codes.
- 1990s, the new decimal coded tags were introduced further increasing the availability of unused codes while improving accuracy and readability.
Millions of juvenile salmon and steelhead are tagged annually. Chinook tagging levels are the highest (~ 50 million), followed by coho (~ 7 million). The remaining species including steelhead, chum, pink, and sockeye salmon tagging levels comprise ~ 3.0 million tags.
This massive tagging effort represents approximately 900 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.
Million of dollars are 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 hundreds of thousands 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.
Some benefits of the CWT program:
- One of the best ways to evaluate wild/natural stocks and their interactions;
- Reliable method to evaluate harvest contribution rates, distribution, survival trends;
- Management decisions based on CWT data acquired in real time activities can be evaluated with immediate results;
- Changes in environment, hatchery practices, and harvest practices can be effectively tracked and factored into management decisions;
- Contributes to resolution of tribal and international harvest allocation issues;
- ESA concerns can be more effectively addressed;
- CWT is currently the only stock identification tool which is Pacific coast-wide in scope and provides information for the entire life cycle of fish.
All Coded Wire Tag related documents including links to scientific publications, agency reports, and Northwest Marine Technology Inc. documents.
Subset of these documents appear under the topic specific categories at the top of this page.
| File | Description | File Date |
|---|---|---|
| Coded-Wire Tag Sampling: The Case for Electronic-Field Detection | A clipped adipose fin served as an effective external mark indicating presence of a coded-wire tag (CWT) in salmon (Oncorhynchus spp.) from the 1960s until the mid 1990s when hatcheries in the Pacific Northwest began mass marking released fish with an adipose fin clip, but not necessarily a CWT. Since then, many CWT sampling programs of commercial fisheries have transitioned to electronic-field detection, while others are still visual-field only, examining snouts from all adipose-clipped salmon, even those without CWTs. Because some CWT salmon are released from hatcheries without any external marks, visual-field only programs also fail to sample these CWTs. In 2012, we used electronic tag detection at a processing plant in Kodiak, Alaska, to scan 1,201 Chinook salmon (O. tschawytscha) caught as bycatch in the US North Pacific groundfish fisheries in the Gulf of Alaska (GOA). Chinook salmon bycatch were also electronically scanned in partnerships with private industry: 3,713 salmon in the 2013–2016 US rockfish fishery in the central GOA, and 611 salmon in testing of salmon excluder devices in 2013 in the central GOA groundfish fisheries. Electronic-field detection increased CWT recovery rates by 20–24% over visual-field detection of adipose-clipped Chinook salmon, and an estimated 64–74% of adipose-clipped Chinook salmon sampled had no CWTs. Visual-field only CWT sampling programs may unnecessarily process large numbers of untagged, adipose-clipped salmon while also recovering fewer CWTs than comparable electronic sampling programs. Citation Michele M. Masuda and Adrian G. Celewycz "Coded-Wire Tag Sampling: The Case for Electronic-Field Detection," Northwest Science 93(2), 102-111, (25 September 2019). https://doi.org/10.3955/046.093.0202 Note: Public access is provided with approval of the Managing Editor of Northwest Science because this research was conducted by federal employees and there is no copyright restriction. Article: https://doi.org/10.3955/046.093.0202 | 2019 |
| Preliminary Review of Fiscal Year 2003 Mainstem and Systemwide Proposals (ISRP 2002-13) | This report provides preliminary comments and recommendations of the Independent Scientific Review Panel (ISRP) and Peer Review Groups on Mainstem and Systemwide projects submitted for Fiscal Year 2003 funding. The Mainstem and Systemwide review is the final segment of the rolling review process, which began in the spring of 2000 and covers all projects funded through the Columbia River Basin Fish and Wildlife Program. This preliminary report provides project sponsors and the public an opportunity to respond to ISRP concerns before the ISRP makes its final recommendation to the Council on October 23, 2002. This report also provides information to the Columbia Basin Fish and Wildlife Authority (CBFWA) for its use in project prioritization and the National Marine Fisheries Service (NMFS) and the Action Agencies’ (U.S. Army Corps of Engineers, U.S. Bureau of Reclamation, and the Bonneville Power Administration) Research, Monitoring and Evaluation Group in its project review and potential revision efforts. | 2002 |
| PSC Workshop on Hatchery CWT Methodology (Regional Information Report1 No. 1 J95- 12) | Preliminary summary edited and condensed by Norma Jean Sands. This workshop on hatchery coded-wire-tag (CWT) methodology was sponsored by the Pacific Salmon Commission (PSC); its purpose was to compare methods currently used in producing CWT data, to review uses of the data, and to make recommendations for standardizing and improving technologies where possible. The workshop was attended by 40-60 people each day with almost 100 different people in total, coming from Alaska, the Yukon, B.C., Washington, Oregon, Idaho, and California. A schedule of the meeting is attached. The last half of the third day consisted of panel workgroups with participation by interested audience members as well as panel participants. There were spirited discussions in all workgroups and each workgroup put together a summary of findings, discussions, and recommendations. These summaries, along with summaries of each panel talk, will be will be compiled in a workshop proceeding which will be published through the PSC | 1995 |
| Coded-Wire Tag Loss Study (WDFW Technical Report No. 65) | Author: Lee Blankenship For each year from 1973 thru 1978, the Washington Department of Fisheries (WDF) has published a report documenting the estimated catch of WDF’s coded-wire tagged (CWT) fish. These have been published as part of the WDF Progress Report series and provide estimated catch by fishery, area and time for each tag group with one or more tag recoveries during that year (WDF, 1976, 1976; Rasch 1977, 1978; Rasch and O’Connor, 1979; and O’Connor, 1980). These reports have treated tag loss inconsistently (tag loss refers to the shedding of CWT’s which had been implanted in the snout of fish). In the 1974 report, a 15% tag loss was used to adjust release figures. The studies in this report were conducted to gain insight into tag loss rates, factors affecting tag loss, length of time over which tag loss occurs, and the numerical significance of naturally occurring adipose fin marks. | 1981 |
| Comparative Injury, Adipose Fin Mark Quality, and Tag Retention of Spring Chinook Salmon Marked and Coded Wire Tagged by an Automated Trailer and Manual Trailer at Carson National Fish Hatchery | Authors: William R. Brignon, Rod O. Engle, David M. Hand, Jesse Rivera, and Douglas E. Olson The United States Fish and Wildlife Service’s Columbia River Fisheries Program Office has been marking and tagging salmon with automated trailers consistently since 2006, in addition to the historically used manual trailers. Some hatchery managers have expressed concern that automated trailers may cause injuries at rates higher than historic marking and tagging techniques. To begin addressing these concerns, in 2006 we evaluated the two types of marking trailers at Warm Springs National Fish Hatchery, Oregon. To complement the study at Warm Springs National Fish Hatchery, in 2008 spring Chinook salmon at Carson National Fish Hatchery were adipose fin marked and coded wire tagged using both an automated and manual marking trailer | 2008 |
| Regional Overview of Coded Wire Tagging of Anadromous Salmon and Steelhead in Northwest America (updated from 1989 version) | Author: J. Kenneth Johnson. Coded wire microtags (CWTs) were introduced in the Pacific Northwest in the late 1960s as an alternative to fin clipping and external tags for identification of anadromous salmonids in the region, particularly those of hatchery origin. Coastwide use of CWTs quickly followed, and fisheries agencies in Alaska, British Columbia, Washington, Oregon, and California established ocean sampling and recovery programs. Now, 54 federal, provincial, state, tribal, and private entities release over 50 million salmonids with CWTs yearly. Regional coordination of these tagging programs is provided by the Regional Mark Processing Center operated by the Pacific States Marine Fisheries Commission. The ‘Mark Center’ also maintains a centralized database for coastwide CWT releases and recoveries, as well as for associated catch and sample data. CWT data are provided to users via interactive on-line data retrieval. | 2004 |
| Overview of the Coded Wire Tag Program in the Greater Pacific Region of North America | Authors: George F. Nandor, , James R. Longwill, and , and Daniel L. Webb. The coded wire tag (CWT) was introduced in the greater Pacific region (Alaska, British Columbia, Washington, Idaho, Oregon, and California) in the late 1960s as an alternative to the fin clip and external tag for identification of anadromous salmonids – particularly hatchery origin fish. Coastwide use of the CWT quickly followed, and fisheries agencies in Alaska, British Columbia, Washington, Oregon, and California established ocean sampling and recovery programs. In 2009 47 Federal, Provincial, State, Tribal, and private entities released more than 50 million salmonids with the CWT yearly. Regional coordination of these tagging programs is provided by the Regional Mark Processing Center (RMPC) operated by the Pacific States Marine Fisheries Commission (PSMFC). The center also maintains a centralized database for coastwide CWT releases and recoveries, as well as for associated catch and sample data. CWT data are provided to users through an interactive on-line data retrieval system. An expert panel review of the CWT system in 2005 identified specific problems with the CWT system. In 2008, a CWT workgroup developed a response and an action plan to address those problems. | 2009 |
| ISRP Response to BPA Project (198201302) Annual Stock Assessment – Coded Wire Tag Program (ODFW) | Response by BPA Project Sponsors to ISRP comments in the preliminary review of Fiscal Year 2003 Mainstem and Systemwide Proposals (ISRP 2002). Questions addressed related to stock selection, mass-mark selective mortality, tagging quality and time tagged groups are held prior to release. | 2003 |
| Random-Sampling Design to Estimate Hatchery Contribution to Fisheries | American Fisheries Society Symposium 7:691-707, 1990 Author: Robert R. Vreeland The results from this case study illustrate some important points that may be relevant to a wide variety of mark-recapture experiments. The sampling effort required to produce reasonably precise parameter estimates was very high. However, the required precision of such estimates depends on the purpose of the study and the intended use of its results. If a lower level of precision is adequate, the required sampling effort can be reduced. [Note: document includes information on tag retention.] | 1990 |
| Vreeland Tag Loss memo 1977 | Memo from Robert R. Vreeland to Kenneth Johnson. Table to help determine the number of fish to sample for wire tag retention. | 1977 |
| Nason Tag Loss memo 1999 | Memo from Kristin Nason to Ron Olson. Subject: Detecting a difference in tag loss rate. This memo is in response to the request for an estimate of the sample size needed to test whether or not there is a difference in the tag loss rates of the clipped and unclipped groups of either a coho or chinook double index tag group. | 1999 |
| Newman Tag Loss memo1987 | Memo from Ken Newman to Ron Olson. Subject: Review of Bob Vreeland's memo on sample size for tag loss estimation | 1987 |
| Planning and Conducting Projects Using Coded Wire Tags (published by NMT) | Written by D. J. Solomon & G. E. Vander Haegen (Northwest Marine Technology, Inc). This document describes all aspects of the deployment of the Coded Wire Tag (CWT) and ancillary equipment. It is primarily aimed at new and potential users, but experienced users may also find it a useful reference if they are considering tagging new species or tagging under different conditions. This manual is not intended to replace the user manuals for each piece of equipment, but rather to complement them to help in the design and execution of overall tagging programs and the selection of the most appropriate equipment. It contains many hints and suggestions for tagging, tag recovery, tag reading, and data handling. Additional resources are available on the NMT website (www.nmt.us). | 2017 |
CWT Retention Resources
| File | Description | File Date |
|---|---|---|
| Preliminary Review of Fiscal Year 2003 Mainstem and Systemwide Proposals (ISRP 2002-13) | This report provides preliminary comments and recommendations of the Independent Scientific Review Panel (ISRP) and Peer Review Groups on Mainstem and Systemwide projects submitted for Fiscal Year 2003 funding. The Mainstem and Systemwide review is the final segment of the rolling review process, which began in the spring of 2000 and covers all projects funded through the Columbia River Basin Fish and Wildlife Program. This preliminary report provides project sponsors and the public an opportunity to respond to ISRP concerns before the ISRP makes its final recommendation to the Council on October 23, 2002. This report also provides information to the Columbia Basin Fish and Wildlife Authority (CBFWA) for its use in project prioritization and the National Marine Fisheries Service (NMFS) and the Action Agencies’ (U.S. Army Corps of Engineers, U.S. Bureau of Reclamation, and the Bonneville Power Administration) Research, Monitoring and Evaluation Group in its project review and potential revision efforts. | 2002 |
| PSC Workshop on Hatchery CWT Methodology (Regional Information Report1 No. 1 J95- 12) | Preliminary summary edited and condensed by Norma Jean Sands. This workshop on hatchery coded-wire-tag (CWT) methodology was sponsored by the Pacific Salmon Commission (PSC); its purpose was to compare methods currently used in producing CWT data, to review uses of the data, and to make recommendations for standardizing and improving technologies where possible. The workshop was attended by 40-60 people each day with almost 100 different people in total, coming from Alaska, the Yukon, B.C., Washington, Oregon, Idaho, and California. A schedule of the meeting is attached. The last half of the third day consisted of panel workgroups with participation by interested audience members as well as panel participants. There were spirited discussions in all workgroups and each workgroup put together a summary of findings, discussions, and recommendations. These summaries, along with summaries of each panel talk, will be will be compiled in a workshop proceeding which will be published through the PSC | 1995 |
| Coded-Wire Tag Loss Study (WDFW Technical Report No. 65) | Author: Lee Blankenship For each year from 1973 thru 1978, the Washington Department of Fisheries (WDF) has published a report documenting the estimated catch of WDF’s coded-wire tagged (CWT) fish. These have been published as part of the WDF Progress Report series and provide estimated catch by fishery, area and time for each tag group with one or more tag recoveries during that year (WDF, 1976, 1976; Rasch 1977, 1978; Rasch and O’Connor, 1979; and O’Connor, 1980). These reports have treated tag loss inconsistently (tag loss refers to the shedding of CWT’s which had been implanted in the snout of fish). In the 1974 report, a 15% tag loss was used to adjust release figures. The studies in this report were conducted to gain insight into tag loss rates, factors affecting tag loss, length of time over which tag loss occurs, and the numerical significance of naturally occurring adipose fin marks. | 1981 |
| Comparative Injury, Adipose Fin Mark Quality, and Tag Retention of Spring Chinook Salmon Marked and Coded Wire Tagged by an Automated Trailer and Manual Trailer at Carson National Fish Hatchery | Authors: William R. Brignon, Rod O. Engle, David M. Hand, Jesse Rivera, and Douglas E. Olson The United States Fish and Wildlife Service’s Columbia River Fisheries Program Office has been marking and tagging salmon with automated trailers consistently since 2006, in addition to the historically used manual trailers. Some hatchery managers have expressed concern that automated trailers may cause injuries at rates higher than historic marking and tagging techniques. To begin addressing these concerns, in 2006 we evaluated the two types of marking trailers at Warm Springs National Fish Hatchery, Oregon. To complement the study at Warm Springs National Fish Hatchery, in 2008 spring Chinook salmon at Carson National Fish Hatchery were adipose fin marked and coded wire tagged using both an automated and manual marking trailer | 2008 |
| ISRP Response to BPA Project (198201302) Annual Stock Assessment – Coded Wire Tag Program (ODFW) | Response by BPA Project Sponsors to ISRP comments in the preliminary review of Fiscal Year 2003 Mainstem and Systemwide Proposals (ISRP 2002). Questions addressed related to stock selection, mass-mark selective mortality, tagging quality and time tagged groups are held prior to release. | 2003 |
| Random-Sampling Design to Estimate Hatchery Contribution to Fisheries | American Fisheries Society Symposium 7:691-707, 1990 Author: Robert R. Vreeland The results from this case study illustrate some important points that may be relevant to a wide variety of mark-recapture experiments. The sampling effort required to produce reasonably precise parameter estimates was very high. However, the required precision of such estimates depends on the purpose of the study and the intended use of its results. If a lower level of precision is adequate, the required sampling effort can be reduced. [Note: document includes information on tag retention.] | 1990 |
| Vreeland Tag Loss memo 1977 | Memo from Robert R. Vreeland to Kenneth Johnson. Table to help determine the number of fish to sample for wire tag retention. | 1977 |
| Nason Tag Loss memo 1999 | Memo from Kristin Nason to Ron Olson. Subject: Detecting a difference in tag loss rate. This memo is in response to the request for an estimate of the sample size needed to test whether or not there is a difference in the tag loss rates of the clipped and unclipped groups of either a coho or chinook double index tag group. | 1999 |
| Newman Tag Loss memo1987 | Memo from Ken Newman to Ron Olson. Subject: Review of Bob Vreeland's memo on sample size for tag loss estimation | 1987 |
CWT Program Resources
| File | Description | File Date |
|---|---|---|
| Regional Overview of Coded Wire Tagging of Anadromous Salmon and Steelhead in Northwest America (updated from 1989 version) | Author: J. Kenneth Johnson. Coded wire microtags (CWTs) were introduced in the Pacific Northwest in the late 1960s as an alternative to fin clipping and external tags for identification of anadromous salmonids in the region, particularly those of hatchery origin. Coastwide use of CWTs quickly followed, and fisheries agencies in Alaska, British Columbia, Washington, Oregon, and California established ocean sampling and recovery programs. Now, 54 federal, provincial, state, tribal, and private entities release over 50 million salmonids with CWTs yearly. Regional coordination of these tagging programs is provided by the Regional Mark Processing Center operated by the Pacific States Marine Fisheries Commission. The ‘Mark Center’ also maintains a centralized database for coastwide CWT releases and recoveries, as well as for associated catch and sample data. CWT data are provided to users via interactive on-line data retrieval. | 2004 |
| Overview of the Coded Wire Tag Program in the Greater Pacific Region of North America | Authors: George F. Nandor, , James R. Longwill, and , and Daniel L. Webb. The coded wire tag (CWT) was introduced in the greater Pacific region (Alaska, British Columbia, Washington, Idaho, Oregon, and California) in the late 1960s as an alternative to the fin clip and external tag for identification of anadromous salmonids – particularly hatchery origin fish. Coastwide use of the CWT quickly followed, and fisheries agencies in Alaska, British Columbia, Washington, Oregon, and California established ocean sampling and recovery programs. In 2009 47 Federal, Provincial, State, Tribal, and private entities released more than 50 million salmonids with the CWT yearly. Regional coordination of these tagging programs is provided by the Regional Mark Processing Center (RMPC) operated by the Pacific States Marine Fisheries Commission (PSMFC). The center also maintains a centralized database for coastwide CWT releases and recoveries, as well as for associated catch and sample data. CWT data are provided to users through an interactive on-line data retrieval system. An expert panel review of the CWT system in 2005 identified specific problems with the CWT system. In 2008, a CWT workgroup developed a response and an action plan to address those problems. | 2009 |
| Random-Sampling Design to Estimate Hatchery Contribution to Fisheries | American Fisheries Society Symposium 7:691-707, 1990 Author: Robert R. Vreeland The results from this case study illustrate some important points that may be relevant to a wide variety of mark-recapture experiments. The sampling effort required to produce reasonably precise parameter estimates was very high. However, the required precision of such estimates depends on the purpose of the study and the intended use of its results. If a lower level of precision is adequate, the required sampling effort can be reduced. [Note: document includes information on tag retention.] | 1990 |
| Planning and Conducting Projects Using Coded Wire Tags (published by NMT) | Written by D. J. Solomon & G. E. Vander Haegen (Northwest Marine Technology, Inc). This document describes all aspects of the deployment of the Coded Wire Tag (CWT) and ancillary equipment. It is primarily aimed at new and potential users, but experienced users may also find it a useful reference if they are considering tagging new species or tagging under different conditions. This manual is not intended to replace the user manuals for each piece of equipment, but rather to complement them to help in the design and execution of overall tagging programs and the selection of the most appropriate equipment. It contains many hints and suggestions for tagging, tag recovery, tag reading, and data handling. Additional resources are available on the NMT website (www.nmt.us). | 2017 |
