Sixth Season of Mass Marking Lake Trout Begins
BY KEVIN PANKOW, GREEN BAY FWCO
Credit: Kevin Pankow, USFWS
Beginning in July 2015 with an expected finish in early October, lab staff will tag and fin clip more than six million lake trout at six hatcheries throughout the Great Lakes basin. The team will begin tagging at Michigan Department of Natural Resources Marquette State Fish Hatchery and then move operations to three Service hatcheries including Pendills Creek National Fish Hatchery (NFH) in Brimley, Michigan, Jordan River NFH in Elmira, Michigan, and Iron River NFH in Iron River, Wisconsin. Those four hatcheries rear all the lake trout stocked into lakes Michigan and Huron. For lake trout that are stocked into lakes Erie and Ontario the team will again be tagging at the Service’s Allegheny NFH in Warren, Pennsylvania and for the first time this year, at the Dwight D. Eisenhower NFH in North Chittenden, Vermont.
The lab operates four automated tagging systems contained in 44-foot mobile trailers that inject coded-wire-tags (CWT) and remove the adipose fin of hatchery reared fish. The CWT is a 1-mm long piece of stainless steel wire etched with a six-digit code that is unique to batches 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, identify fish movement within and among the lakes, and assess the resultant contributions to regional fisheries. Biological data collected will also help to evaluate the health of the populations by providing growth rates and age composition of the fish at time of capture. In addition, the tag recoveries allow managers to determine post-release survival of various strains, hatcheries, and stocking locations providing the ability to evaluate the performance of hatchery rearing and stocking practices.
Since the program’s inception in 2010, nearly 48 million fish stocked into the Great Lakes have been mass marked by the Lab. The program is currently funded by the Great Lakes Restoration Initiative.