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Lake Trout Restoration Program
Program Contact: Aaron Woldt (Aaron_Woldt@fws.gov)
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The lake trout, Salvelinus namaycush, is one of the few native deepwater predators found in the Great Lakes. Their populations in Lake Huron and Lake Michigan were decimated in the 1950's by over-fishing and predation by the exotic sea lamprey. Many management agencies are currently involved in efforts to restore lake trout in Lake Huron.
The Alpena NFWCO provides Service leadership for lake trout restoration activities in Lake Huron and provides Service coordination for the following coordinated lakewide lake trout studies being conducted in Lake Huron:
Lake trout studies are conducted by marking hatchery raised lake trout in the snout with small wire tags called coded-wire tags (CWT). The fish are then stocked into the lake, grow to harvestable size, and captured by commercial or sport fisheries or during fishery surveys conducted by state, federal, or tribal management agencies. The snout and head of captured fish are examined and the CWTs are removed and examined for the unique code.
View the study plan.
Since 1994, Alpena NFWCO has recoverd CWTs from all sport harvested lake trout in U.S. waters of Lake Huron, all tribal commercial and assessment fisheries, as well as from our own assessment activities in Lake Huron. In addition the office provides assistance the Michigan DNR for CWT recovery from the assessment fisheries in Lake Huron. Alpena NFWCO also provided leadership for the development of a standardized CWT database that houses all tag recoveries from Lake Huron.In 1985, studies were initiated in U.S. waters of Lake Huron to evaluate comparative plantings of several strains of lake trout. The experimental lots of lake trout were reared in National Fish Hatcheries, marked with CWTs for later analysis of differential performance, and stocked at specified locations. By stocking various strains and comparing their performance, it was hoped that a strain(s) could be identified which performs better than others, both in terms of establishing spawning populations on historically important reefs and surviving the presence of sea lamprey.
Two locations were chosen for the experiments, a mid-lake reef complex called Six Fathom Bank and a nearshore site along the south shore of Drummond Island in northern Lake Huron - the Northern Refuge. Both sites contain extensive areas of habitat suitable for lake trout reproduction. To eliminate bias associated with harvest, the sites had to be relatively free of fish extraction. The remoteness of Six Fathom Bank (approximately 35 miles from the nearest shore access) provided such protection. As the lake trout population at Six Fathom Bank grew and expanded, additional protection was warranted. In 1997 the State of Michigan and Ontario Ministry of Natural Resources designated Six Fathom Bank as the first international lake trout refuge in the Great Lakes. The Northern Refuge was designated a state lake trout refuge and closed to fishing harvest in order to provide protection from fishing pressure.
This study was completed in 2004 and the results of the study were published in the North American Journal of Fisheries Mangement (Madenjian et al. 2004). View the abstract.Calculation of harvest limits (HL) in northern Lake Huron has suggested that there is substantial south to north movement of stocked lake trout from MH-2 to MH-1. Such movement significantly complicates mortality and HL estimates. In an effort to quantify movement patterns, the Lake Huron Technical Committee (LHTC) requested four lots of CWT fish (60 K each) from the federal hatchery system. In the spring of 1992 lots of 60,000 lake trout (1991 year class) were stocked at Adams Point, Middle Island, Sturgeon Point, and Point Aux Barques. Stocking coordinates were selected and provided to the federal hatchery system. Three year classes (1993, 1995, 1997) of similarly marked fish were stocked in alternate years at those locations as replicates of the 1992 study fish. A repeat of the study, commencing with the stocking of the 2000 year class in 2001, added a fifth site in Ontario waters of the southern main basin of Lake Huron near Point Clark. Due to the proposed development of a rotating pulse stocking strategy, periodic updates to the movement matrix will be essential for monitoring of lake trout stock status in regions of Lake Huron.The National Fish Hatchery system has altered its program to improve the quality of lake trout stocked in the upper Great Lakes. To improve the quality of the product fewer fish are being raised in the hatcheries, and they are being fed optimum rations throughout the hatchery cycle. As a result of the change, larger and fewer (35 percent) yearling fish are available for stocking in each of the lakes. It is hoped that improved quality will result in significantly better survival, and consequently in no net loss to lake wide abundance. The proposal was made to the LHTC in July 1994 and the endorsed recommendation passed on to the Lake Huron Committee where it was approved. To evaluate the change, the LHTC has designed a study to compare the new hatchery product with the historical "standard". The study is part of the movement study previously discussed.
