BY KEVIN PANKOW, GREEN BAY FWCO
The Great Lakes Fish Tag and Recovery Lab, headquartered at the Green Bay Fish and Wildlife Conservation Office, has concluded mass marking the 2015 year class of lake trout. The team mass marked 5,032,941 lake trout with a coded wire tag (CWT) and adipose fin clip. These fish, destined for Lakes Michigan and Huron, are raised at three FWS Region 3 National fish hatcheries (NFH) and one Michigan Department of Natural Resources State Fish Hatchery (SFH).
The 2015 season began at Marquette SFH where over 218,000 lake trout were mass marked July 10th to 12th. During August 4th to September 2nd, mass marking operations resulted in 1.15 million lake trout completed at Pendills Creek National Fish Hatchery (NFH); operations at Jordan River NFH from August 5th to September 26th yielded 2.39 million mass marked lake trout; and 1.36 million lake trout were mass marked at Iron River NFH September 23rd to October 7th.
To accomplish this monumental task, the lab operated four mobile tagging trailers that automatically inject a CWT and remove the adipose fin of hatchery reared fish with little human handling. The CWT is a 1.1-mm long piece of stainless steel wire etched with a six-digit code that is unique to a batch of fish, referring to its year class, strain, stocking location and hatchery origin.
The information gained from CWT returns provides the Service and its partners the ability to estimate levels of natural reproduction, evaluate post-release survival of various strains, identify fish movement within and among the lakes, assess the contributions of the hatchery reared fish to regional fisheries, and to evaluate the performance of various hatchery rearing and stocking practices. Biological data collected from tagged fish will also help to evaluate the health of the populations by providing growth rates and age composition of the fish at time of capture.
Since the program’s inception in 2010, over 54 million fish stocked into the Great Lakes have been mass marked by the Lab. The program is currently funded by the Great Lakes Restoration