LANSING, MI – Each year the Michigan Department of Natural Resources assesses lake trout populations in lakes Superior, Michigan and Huron, using a fleet of specially designed Great Lakes research vessels to determine trends in their populations and their status toward being self-sustaining.
The results of the 2015 surveys and outlook for 2016 for each lake are as follows:
Lake trout abundance is monitored through surveys conducted annually in the spring for adult abundance and summer for juveniles. Lake trout abundance in Michigan waters of Lake Superior has remained stable over the past 10 years following a decline from peak abundances in the later part of the 1990s.
Juvenile lake trout numbers in the survey declined following the same trend seen since 2011. Sea lamprey-induced mortality, the major source of lake trout deaths in Lake Superior, continued to remain above the target level as it has since 1992. The 2016 outlook is to expect similar populations of adult and juvenile lake trout in Lake Superior as seen in 2015.
During the 2015 field season, lake trout were sampled in northern and eastern Lake Michigan from May to June, with more than 1,500 fish collected. Overall, survey catch rates were lowest in northern Lake Michigan and higher in Grand Traverse Bay and the eastern shoreline of Lake Michigan. Lake Trout catch rates have been increasing from Arcadia to Naubinway and were above the 10-year average in 2015. Survey catch rates were lower than the 10-year average in southeastern Lake Michigan and Grand Traverse Bay. A broader range of ages and sizes is being seen in northeastern Lake Michigan and Grand Traverse Bay.
Numbers of deposited lake trout eggs remain low but were higher in 2015 compared to the previous two years and there is evidence of natural recruitment in Lake Michigan. Because of reductions in Chinook salmon populations and stable to expanding lake trout populations, the DNR expects to see higher recreational catch rates of lake trout that should include larger fish in 2016.
The 2015 surveys of lake trout populations showed a continued trend to becoming self-sustaining. From the eastern Upper Peninsula to the Thumb coast, the 2015 surveys documented that wild lake trout now comprise 69 percent of the fish under 21 inches and most of the fish under 29 inches. Survey catch rates of wild lake trout have increased dramatically since 2004. Stocked lake trout also were collected and ranged from 3 to 22 years old. Lake trout survey catches also showed a continued rapid expansion of age composition, which indicates a low annual mortality for adult lake trout.
Sea lamprey wounding rates decreased 58 percent from 2014 to only five per 100 fish in 2015, the lowest value since 1970. Survival of stocked lake trout showed a continued decline, reduced by an estimated 81 percent since 2009, and has shown no sign of improvement since the 2003 stocking that coincided with alewife collapse in Lake Huron. The DNR expects to see stable numbers of lake trout in 2016 with a continued decline in the survival of stocked fish and increasing numbers of wild fish in Lake Huron.
“These data indicate that Lake Superior continues to be a self-sustaining lake trout fishery and the other Great Lakes are continuing on that track,” said Gary Whelan, DNR fisheries research program manager. “The data also show anglers should expect continued good fishing for lake trout in our Great Lakes waters in the upcoming season.”
For more information on lake trout in Michigan, visit the Michigan Fish & How To Catch Them web page.