Fish and Aquatic Conservation

 artwork of a Lake trout

Fish illustration by Laury Zicari, USFWS, Retired

Lake trout

My Scientific Name

Salvelinus namaycush

By the Numbers

We can be up to 3 feet in length and weigh up to 40 pounds. The longest one on record is 50 inches and the heaviest on record is 102 pounds.

How to Identify Me

As adults, we have a big round head and large mouth, a deeply forked tail, and light spots on a dark green to grey body.

Why I Matter and What's Been Happening

Back in the 1800’s and early 1900s people would fish for us, then sell us to the public for eating.

By the 1950’s, we were almost eliminated because of overfishing, pollution and an invasive* species called the sea lamprey. The United States and Canada have been working together to improve water quality in the Great Lakes and make sure lake trout don’t become overfished again. People also are working to reduce the numbers of sea lamprey in the Great Lakes, which definitely helps us out.

My Status

Good News! Our populations in Lake Superior are doing well. And our numbers in Lake Huron and in areas of Lake Michigan also are improving.

* A native species is a species that has always occurred in an area naturally, and was not introduced by humans. An invasive species is not native to an area and can cause harm to native plants and animals.

did you know image
  • Lake trout are native* only to northern North America, from Alaska to Nova Scotia, and throughout the Great Lakes. They were introduced in states west of the Rockies where they are not native (Figure 1).
  • They prefer to live in cold (48-52⁰F) deep lakes greater than 50 feet, and you can find them at depths well over 200 feet too!
  • They are the largest trout in the Great Lakes. Lake trout begin reproducing at 6 to 7 years of age, and can live over 25 years.
  • The oldest lake trout on record was 70 years old.
  • Lake trout are fast-swimmers! Young lake trout eat plankton, insects and small invertebrates, while adults eat smaller fish.
  • Lake trout are a top predator in the Great Lakes. They help maintain balance between all the other species, which helps maintain food and space for everything in the Lake.
  • They are quite exciting to catch, and they are delicious to eat.
  • Our national and state fish hatcheries are a big help in raising fish and stocking them back into our Great Lakes!

a map of USA and Canada, showing the range of lake trout

Figure 1 – Where lake trout are currently found.
Credit: Atlas of North American Freshwater Fishes.

More About Us image

a close up of lake trout head

This lake trout was raised at a National Fish Hatchery and stocked into our lakes to help boost local populations. Lake trout don’t reproduce until they are at least 6 to 7 years old, so it takes a long time for populations to rebuild themselves when their numbers are really low. Fish hatcheries help by raising and stocking fish, until they can maintain healthy populations on their own.

a lake trout body with an open wound caused by sea lamprey

The invasive sea lamprey preys upon other fish by latching onto their body and “sucking” body fluids from the host fish. Along with pollution and overfishing, the sea lamprey were responsible for drastic declines in lake trout populations in the Great Lakes. We now have better ways of controlling sea lamprey which is helping the lake trout to rebuild their populations.

hands holding a lake trout above the water

Lake trout can be real wanderers traveling many miles in search of food. And some return to the same spawning sites each year. This lake trout has a tag just behind its dorsal fin. Tagged fish help biologists understand more about lake trout migration behavior and where they prefer to live and breed. Biologists monitor their growth over time which tells us how well the lake is supporting lake trout.

Learn more about Lake Trout!


How you can help statement: Get to know me, if you don’t already. Help make me visible to people who don’t have the chance to see me by sharing your stories about me. Get involved in efforts to help conserve my habitat and maintain my populations into the future.