Since the 1970s the SWFSC has collaborated with American Fishermen's Research Foundation (AFRF) in tagging studies of albacore. Through these studies we have learned that juvenile albacore (2 to years of age) make trans-Pacific migrations in their younger years between Japan and the West coast of North America. To date over 24,000 albacore have been tagged with conventional dart tags and 1,245 of these have been recovered.
In Spring of 2001 AFRF and the SWFSC began a pilot project to learn more about the migration habits of North Pacific albacore, Thunnus alalunga in an effort to allow the incorporation of detailed migration movements into stock assessment models. Archival tags are a recent technical innovation that are being used to collect daily locations (through light level data recorded by the tag), internal temperature of the fish's abdomen, ambient water temperature, and depth.
The archival tags used in this study are the Lotek LTD2310 and the Wildlife Computers TDR-Mk9.
Download and view a new version of the tagging procedures in WMV format (Windows Media Video) by clicking here (3.6MB).
The overall objective of the project is to understand North Pacific albacore movements well enough to be able to use them effectively in stock assessment modeling or for management guidelines. To achieve this goal it is estimated that we will need to recapture at least 50 archival tags over a five year period. In the first two years of the project we sought to develop appropriate tagging procedures, and develop deployment methods to best meet the objectives of the project. In those first years, 43 “dummy” tags which are plastic tags of the same size and shape as the archival tags, but lack the electronics, were deployed. Five hundred and four true electronic archival tags have since been deployed in albacore off the west coast.
A $500 reward is offered for the return of an albacore tagged with one of these archival tags to the SWFSC. An anchor worm parasite is often mistaken for these tags. View a comparison of the tags and parasite to see the differences.
In October, 2003 the first tag recovery was made from an albacore at liberty for nearly 12 weeks. The fish was tagged July 27 2003 aboard the San Diego based sport boat SHOGUN during a tagging trip sponsored by the Tagging of Pelagic Predators (TOPP ) project. The tag was recovered October 18, 2003 onboard the San Diego based sport boat PEGASUS. This is only the second recovery of an archival tag for this species. The data demonstrated that the fish forayed into deep water, down to nearly 300 meters, and the diving activity occurred primarily during daylight hours.The following figures show the data recovered from the tag including a record of depth, water temperature, peritoneal cavity temperature and light level for the entire deployment and detailed data for October 3-4, 2003.
The tags record ambient ocean temperature every 60 seconds. From these measurements we can generate a thermal profile of the water through which the fish swims.