Great Lakes Fish Tag and Recovery Laboratory
2014 Coded-Wire Tag Extractions Completed
BY KEVIN PANKOW, GREEN BAY FWCO
The Great Lakes Fish Tag and Recovery Laboratory, headquartered at the Green Bay Fish and Wildlife Conservation Office, completed extraction of coded-wire tags (CWTs) from mass marked Chinook salmon and lake trout recovered in the Great Lakes for the fifth season.
The Council of Lake Committees, under direction of the Great Lakes Fishery Commission, in 2005 requested to establish a program to mass mark stocked salmonids in the Great Lakes; thus in 2010 the Great Lakes Fish Tag and Recovery Laboratory was created. The goals of the program are to aid fishery managers in determining the contribution of stocked versus wild fish to the fishery, evaluating the movement patterns and homing of stocked fish, and post-release survival of different strains or from different hatcheries or stocking locations.
To help answer these questions the lab receives snouts containing CWTs from cooperating agencies on lakes Michigan, Huron and Ontario. The snouts are collected by 13 Service funded biological technicians, state agency creel clerks, tribal agencies and anglers. The sources include fishing tournaments and derbies, fish cleaning stations, assessment and creel surveys, weir collections and voluntary returns by anglers. The lab operates four mobile automated tagging trailers that inject the CWT, a 1-mm long stainless steel piece of wire, and adipose fin clip stocked salmon and trout at hatcheries when the Chinook salmon and lake trout are three to five inches in length. The adipose fin clip indicates to collection agencies and anglers the stocked fish has a CWT injected into its snout, and should be collected to send to the lab for processing.
In 2014, the lab processed 18,782 samples, which has been a steady increase from the previous years. This is due to an increase of CWT fish that are tagged and recruiting into the catchable population and an increase in recovery effort. To complete the tag extractions in less than three months, the lab utilized a team of four biologists, four intermittent employees and eleven seasonal bio-technicians. The snouts are dissected to extract the CWT, which is then examined under a microscope to read a 6-digit code that reveals the year class, hatchery of origin and, at times, the stocking site of the individual fish. This information is compiled with biological data collected about the fish and used to help state and federal fishery agencies with stocking decisions and evaluations of the effectiveness of their programs. Since the program’s inception in 2010, the lab has processed over 50,000 samples and extracted 46,000 CWTs.