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Coded Wire Tags Successfully Applied to Walleye Pollock 

 The walleye pollock Theragra chalcogramma is a species of enormous commercial importance.  This member of the cod family (Gadidae) is utilized in several markets with most of the harvest being used as processed fish products such as surimi and fish sticks.

  The pollock fishery in the North Pacific and Bering Sea is relatively new and has grown rapidly.  As late as the mid 1970’s walleye pollock were of little importance to North American Fishermen.  In recent years, the total annual catch, most coming from the Bering Sea, averaged 13 billion pounds; the average U.S. catch is 2.9 billion pounds valued at $242 million.

In the fall of 1993, Ray Buckley of the Washington Department of Fisheries, and the biological staff of Northwest Marine Technology, in cooperation with the Point Defiance Zoo Aquarium in Tacoma, WA, began a study to determine: Coded Wire Tag retention, handling induced stress, mortality, and effects of tagging on growth of walleye pollock.

A small trawler, the Brendan S., was chartered out of Port Townsend, Washington to collect the pollock, and arrangements were made to hold the fish at the aquarium in Tacoma.

A total of 34 pollock (T.L. x=123.2 mm) and 12 tomcod Microgadus poximus (T.L. x= 113.4 mm) were used in the study.  The fish were tagged with a single length Coded Wire Tag in the nape musculature  (posterior to the cranium and just off the midline).  A Mark IV injector, equipped with a needle support tube and adjusted to the fixed needle mode, was used to tag the fish.

The tagged pollock grew at a comparable rate to the documented rates the wild.  Tag retention has remained at 91% through 126 days.  No mortality resulted from three subsequent tag retention checks.

Coded Wire Tagging walleye pollock for a Peterson estimate provides a method to collect more accurate information relating to population structure and size, exploitation rates and other data required to better manage the resource.

Such a program would require capturing and releasing large numbers of fish at sea.  Recovering the tags from the harvest would require incorporating automated detection and sorting equipment into the fish processing system; methodology presently used to recover tags from Atlantic herring.

For further information please contact:

R. Buckley, Dept. of Fish and Wildlife,

600 Capitol Way N., Olympia, WA 98501

(206) 902-2828, FAX (206) 902-2944

F. Haw, Northwest Marine Technology, Inc. 

955 Malin Lane SW Suite B,

Tumwater, WA 98501

(360) 596-9400 FAX (360) 596-9405

biology@nmt.us

Northwest Marine Technology, Inc.                   (360) 468 - 3375

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Last edited: 02 Dec 2008