Testing electronic archival tags in Alaska salmon
Exxon Valdez Oil Spill (EVOS) Project

Derek R. Wilson, Phil Richards and Dr. Jennifer L. Nielsen

Background

Pacific salmon life histories have been extensively studied.  However, many questions still persist concerning the early distribution of smolts and post-smolts in the marine environment. The first year in a marine environment is the most dangerous and difficult for young salmon and its affects are crucial to the development of healthy adult salmon stocks.  With the aid of archival tags, we can document critical marine habitats and their relationship to the health and survival of salmonids in their first year at sea.  Newly designed archival tags are small enough to be surgically implanted into the body cavity of young salmon. These tags record temperature, pressure, and light data from the surrounding habitat.  These data can be used to define critical habitat and plot movement patterns of Pacific salmon in the marine environment. 

Coho salmon have been chosen as the pilot species to test this new technology because of high rearing success in hatcheries and the tendency of males to return as jacks after only 6 months at sea.  A minimum size of 180 mm is recommended to effectively tag juvenile salmon with internal archival tags and 150 mm for soft VI-alpha tags (Visible Implant Alphanumeric).  Coho between 150 mm to 300 mm will be tagged, observed for 2-4 weeks, and released into their natal stream during normal coho smolt out-migration.  Recovery of the archival tags is dependant on a strong sports fishery, commercial fishery, and a fish weir below spawning grounds at the release stream.

Project Goal: 

Test the effectiveness of archival tags in collecting habitat data in marine environments from salmonids in Alaska.

Objectives:

1. Raise hatchery coho to a minimum size of 150 mm prior to smoltification. 

2. Tag each coho salmon for individual identification and record retention rate. 

3. Implant archival tags into a sub-sample of juvenile coho. 

4. Release coho smolts into Ship Creek, spring 2001, 2002, 2003. 

5. Collect archival and I.D. tags from summer 2001 through fall 2004. 

6. Plot coho movements in Cook Inlet by correlating tag data with sea surface temperatures, bathymetry, and geolocation estimates. (Objective will be met in 2002).

(continued to Objective 1)

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