DULUTH – Minnesota Sea Grant fish experts are offering anglers a quicker, easier way to tell the difference between rainbow trout and coho salmon, two similar fish caught in Lake Superior and its tributaries.
Sea Grant has a free sticker explaining the visual differences between fish that can often be caught at the same time, in the same locations, and with the same lures across much of the big lake.
It is important for anglers to know the difference. While Lake Superior anglers can legally raise up to five salmon per day in Minnesota and Wisconsin waters, they may be able to raise only one wild steelhead or none at all.
Contributed / Minnesota Sea Grant
Sea Grant officials, based at the University of Minnesota Duluth, developed the decal with input from members of the Minnesota Steelheader and Minnesota Trout Unlimited organizations and staff from the Minnesota Department of Natural Resources. The fish images are by Joseph Tomelleri, a nationally acclaimed fish illustrator.
The stickers began going up along the North Coast in 2022 for anglers to stick on their boat windows or tackle boxes. They are now available online for a quick reminder. You can download a digital copy of the sticker for easy reference on your phone, or request a printed copy at seagrant.umn.edu/programs/fisheries-and-aquaculture-program/steelhead-v-salmon.
In Wisconsin’s Lake Superior waters, anglers are only allowed to keep one rainbow trout per day and it must be at least 26 inches long. In Minnesota’s Great Lakes waters, anglers must release all wild-caught rainbow trout. Only hatchery-raised and stocked rainbow trout with an adipose fin trimmed on the upper rear portion of their backs may be kept in Minnesota.
Contributed by Nick Peterson/Minnesota DNR
And because Lake Superior coho salmon historically were not very large and taste delicious, many misidentified steelhead under 26 inches are preserved. Biologists point out that it doesn’t do much good to have protective rules for rainbow trout if fishermen raise them thinking they are coho salmon.
Misidentification of trout and salmon has always been a problem at some level in the Great Lake and its tributary rivers. But it may be a bigger problem as an increasing number of novice Lake Superior anglers venture into the big lake and have less experience catching Great Lakes trout and salmon.
Wild steelhead hold their own in the western end of Lake Superior. While they are below their peak population of 50 years ago, they are breeding well in some North Shore streams and Wisconsin’s Bois Brule River.
Minnesota’s wild steelhead catch-and-release regulation has been in place since 1997 to protect wild steelhead and allow them to spawn in an attempt to boost their abundance after their numbers plummeted. The regulation has been successful in halting the decline of steelhead along the North Coast.
Contributed / Michigan Sea Grant
“The availability of a digital version on the Minnesota Sea Grant website should help ensure the continued successful rehabilitation of wild steelhead in Minnesota’s portion of Lake Superior,” said Davin Brandt, president of Minnesota Steelheader.
While the misidentification problem probably isn’t enough to reduce steelhead numbers, it still happens often enough to warrant increased education for anglers, said Don Schreiner, a Minnesota Sea Grant fisheries expert and former Minnesota DNR fisheries biologist. Fishery surveys by DNR fisheries staff and checks by Minnesota DNR conservation officers show that quite a few anglers are still making the mistake.
“Although the catch-and-release regulation for rainbow trout has been in place for more than 25 years, many anglers still misidentify and inadvertently catch rainbow trout,” Schreiner said. “We wanted to develop a tool that was readily available on the water to protect wild rainbow trout from unintentional and/or illegal take.”
Fin tips, tail (and mouth)
Schreiner says the safest method to distinguish steelhead from salmon is by pinching their rear or anal fin. When compressed, the steelhead’s most pronounced fin will touch the body beyond the base of the fin. The shorter, less pronounced coho tail will compress to touch the body of the fish in the middle of the fin base.
Contributed / Minnesota Sea Grant
Veteran Lake Superior anglers often identify a steelhead by its general appearance. Rainbow trout caught in the big lake are usually large, over three pounds, and almost always jump during the fight.
Coho salmon typically weigh 3 pounds or less and don’t jump as much. But, thanks to a record harvest of cisco and smelt salmon for salmon and trout consumption, coho salmon have been getting bigger over the past two summers, well over 3 pounds in many cases, including new Minnesota state records set in September 2023 and, tentatively, again in May of this year.
Those larger coho salmon may confuse the issue even more, Schreiner said.
“I don’t think fishermen can be reminded of this too many times. It may be especially important this year with the large number of coho caught weighing over three pounds,” Schreiner said.
Another tip: Unlike salmon, steelhead do not easily lose their scales when dropped on the floor of the boat or handled. Coho sheds scales most of the time.
You can also check the queue. Steelhead have a mostly straight, flat or square trailing edge on the tail. Cohos have a more pronounced fork or V shape at the back of their tail.
Another way to quickly identify a rainbow trout is to check the color of the inside of its mouth. The inside of a rainbow trout’s mouth is white. The inside of the mouth of any coho or Chinook (king) salmon is dark gray or black.
“The mouth and tail fin criteria are good if you have both fish in your hand and can compare them side by side, as they are both somewhat subjective… What part of a fork is a fork?” he said. Schreiner. But what if you just caught one? The anal fin is always revealing, he said. “When compressed against the body, does the tip extend to or beyond the base, in the case of rainbow trout, or does it fall into the base, in the case of salmon?”
Lake Superior Fishing Regulations
- Wild, unclipped rainbow trout – just catch and release.
- Stocked rainbow trout, cutfin rainbow trout, rainbow trout, or Kamloops trout: daily and possession limit of three, minimum size 16 inches.
- Brook trout and river trout: daily and possession limit of one with a minimum size of 20 inches.
- Brown trout: Daily and possession limit of five, with only one over 16 inches.
- Lake trout: daily and possession limit of three.
- Salmon: daily and possession limit of five, all types.
- Walleye: Daily and possession limit of two, minimum length 15 inches.
You must have a Minnesota fishing license and a trout stamp to fish Minnesota’s Lake Superior waters. For complete regulations, visit dnr.state.mn.us and search for fishing regulations.
- Trout (steelhead, brown, brook or splake trout): Daily and possession limit of five, of which only one can be a rainbow trout and only one can be a brook trout. The minimum size for rainbow trout is 26 inches and for brown trout and splake is 15 inches.
- Lake trout: Daily and possession limit of three, minimum 15 inches and only one may be larger than 25 inches.
- Salmon (all types): Daily and possession limit of five.
- Walleye: Daily and possession limit of five, minimum size 15 inches and only one may be larger than 20 inches.
You must have a Wisconsin fishing license and trout stamp to fish in Wisconsin’s Lake Superior waters. For complete regulations, visit dnr.wisconsin.gov/topic/fishing/regulations.
