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Fisheries crews across the Great Lakes basin are gearing up for another season of lake trout stocking. Over a two-month period, millions of lake trout carefully reared year-round in national fish hatcheries will finally make their way back to their home waters.
A comeback for lake trout was half a century in the making when the extra boost from the Great Lakes Restoration Initiative accelerated the recovery of this once-devastated fishery. Thanks to these steady investments, we at the bet365下载ios - along with a network of partners across the Great Lakes waterscape - can begin to celebrate the return of these native fish.
Restoration began as long ago as the 1960s, when lake trout were nearly gone from the Great Lakes after suffering from a combination of overharvest and sea lamprey predation. All that remained were remnant populations in Lake Superior and a small population in Lake Huron.
Today, lake trout are fully recovered in Lake Superior and notably closer to that goal in others. We have been able to reduce stocking lake trout in Lake Huron by 60% over the last 5 years due to natural reproduction success. Over the last 10-15 years, we are also seeing more evidence of reproduction in Lake Michigan, especially in areas where large numbers of lake trout historically gathered during spawning. Evidence of reproduction has been coming more slowly for Lakes Erie and Ontario where recovery is more challenging.
Some crucial components of the restoration program simply would not exist without the Great Lakes Restoration Initiative, particularly the mass marking program. This is a primary way of gathering information on how stocked fish are faring so partners can make well-informed management decisions going forward. The initiative also has made it possible to greatly improve our hatchery facilities so we can raise healthier fish to meet our goal of restoring self-sustaining populations.
It takes a network
Our agency contributes extensive expertise and resources for lake trout restoration. We have a leading role in what is notably the largest freshwater fisheries restoration effort in the world in terms of geographic scope, number of partners involved, number of fish stocked and sustained commitment.
The Great Lakes Fishery Commission, established in 1954, is the main hub for partners鈥 coordination on lake trout and other fisheries conservation. Lake by lake, the commission brings partners together to set fishery restoration benchmarks and monitor progress. Tribes, First Nations, states and provinces make fisheries management decisions for their waters, including where and how many lake trout to stock to meet restoration targets. Our agency鈥檚 role supports this partner network鈥檚 strategic decision-making.
Double trouble
Lake trout were already struggling from overharvest when sea lamprey invaded the lakes and preyed on lake trout en masse. Since 1958, a sea lamprey control program spearheaded by the Great Lakes Fishery Commission, working with the bet365下载ios and the Department of Fisheries and Oceans Canada, has relied on a lampricide called TFM to specifically target sea lamprey in their larval stage. Partners have now reduced sea lamprey by 90% in most areas. Dealing with the sea lamprey threat was a priority to ensure fish stocking could succeed.
Hatcheries to the rescue
Since the 1960s, the lake trout restoration program has relied on stocking hatchery-raised fish to supplement wild populations. We are now releasing 3.7 million hatchery-reared fish every year in the four Great Lakes where lake trout are still charting a comeback.
It all starts with what we call egg takes. Every year, our vessels are out on the Great Lakes for various fisheries surveys. Every 7-10 years during these surveys, we capture a small number of wild lake trout to collect eggs from females and milt from males to create future broodstock broodstock
The reproductively mature adults in a population that breed (or spawn) and produce more individuals (offspring or progeny).
Learn more about broodstock .
Future broodstock are first isolated at our Genoa National Fish Hatchery in Wisconsin to clear health inspections over an 18-month cycle. This allows us to sample for genetic diversity and perform fish diagnostics to help ensure we raise healthy fisheries for future stocking. Five other national fish hatcheries in Michigan, Pennsylvania and Wisconsin will eventually raise lake trout for stocking from these healthy lines.
Our Midwest Fisheries Center in La Crosse, Wisconsin, and our Northeast Fishery Center in Lamar, Pennsylvania, provide fish health services for all the hatcheries that rear lake trout for reintroduction.
Marking our progress
Before lake trout are stocked in the Great Lakes, we mark them with a small fin clip and coded tag so we can continue to learn about their movement, life cycle needs, survival and reproduction. Our fish tagging and lake surveys provide all kinds of information that eventually guides our partners鈥 fisheries management decisions, such as the best locations and how many fish to stock, as well as harvest regulations.
Our Green Bay Fish and Wildlife Conservation Office in Wisconsin travels to all lake trout-rearing hatcheries serving the Great Lakes to mark and tag fish prior to their release. A mass marking/tagging trailer is employed to tag as many as 8,500 lake trout per hour. Our experts in several fish and wildlife conservation offices throughout the Great Lakes basin analyze vital information from recovered mass-marked fish.
Lake trout will be considered restored when stocking is no longer necessary because we see enough populations reproducing sufficiently on their own to remain robust and replenishing. When we reach that goal for this magnificent fishery, the Great Lakes Restoration Initiative will have been a pivotal part of our progress.
