Water temp is key to locating Great Lakes trout, salmon

If there’s one absolute about how water temperatures affect salmon movement in the Great Lakes, it’s that there is absolutely no magic formula for homing in on the hottest bite.

That’s the consensus of charter captains and other longtime big-water experts from Wisconsin, Michigan, Illinois, and Indiana who agree that many factors contribute to when and where you’ll catch trout and salmon.

Decades ago, it was common to hear that you had to look for 50- to 55-degree water to score on chinooks and cohos. While that’s still a decent range, some of the biggest midsummer kings will be caught in water 10 degrees colder than that off some ports and nearly 10 degrees warmer at others.

Great Lakes author and charter captain Dan Keating, of Antioch, Ill., agrees that there’s a wide range of water temperatures where salmon can be caught, but he still has his favorites.

In May, when water temperatures can range from the upper 30s to low 50s – depending on the lake, port, and prevailing winds – Keating looks for the warmer near-shore waters.

That’s where cohos are smacking flies, spoons, and crankbaits off the northern Indiana and Illinois and southern Michigan and Wisconsin ports.

Come summer, cohos can be found scattered and suspended higher in the water out deep or moving up the shoreline, often sticking near bottom to find the cooler water.

“I like 50 to 54 degrees for cohos,” Keating said. “Come summer, the group that seems to work its way up the shoreline might be in water as warm as 62 degrees, but they’re hard to catch other than first and last daylight.”

Keating said the spring coho fishery has been excellent again this year, with big numbers of 2- to 4-pound fish, a few 5-pound-plus specimens, and an occasional trophy pushing 10 pounds.

“The cohos have had a good number of 2- to 4-inch alewives in them,” Keating said.

Only a few chinooks have been reported so far, but May typically brings in a nice mix of salmon and trout species as the lake gradually warms up.

Speaking of kings, Keating said he prefers cold water – 42 to 48 degrees – for summer chinooks. While they can be caught from water colder or warmer than that, that’s his favorite range for the most aggressive trophies.

Keating said some ports, especially Milwaukee and Waukegan, can have water 10 degrees warmer at the same depth that he’s catching fish at in Winthrop Harbor. In other words, they’re still getting bites in water well into the upper 50s or even low 60s at times. He believes that’s a product of a lot of nutrients in the water attracting baitfish, and the salmon just can’t resist moving in for an easy meal.

Spring and summer tips

Trolling small orange or red flashers ahead of smaller flies behind planers boards probably produces more cohos than any other presentation, but it’s certainly not the only way.

It’s not at all unusual for near-shore brown trout trollers or pier and shore casters to have a salmon smash their spoons and crankbaits. Bottom line: Go with a spread of your favorite baits in a variety of sizes and colors, and see what the fish prefer.

Many of today’s Great Lakes anglers employ some sort of sub-surface temperature gauge to see where the thermoclines are, or have sophisticated locators that show major underwater breaks as a different color, or a bold line.

Such knowledge can really pay off when the fish are suspended over deep water. Keating likes to focus a lot of effort on the bottom of the thermocline, or just under it.

Another thing to watch for is when off-shore winds push warm water out and upwell cooler water near shore. In summer, that can sometimes mean catching fish very shallow at dawn, especially.

Outside of first and last light, you can still score on summer salmon that you know are lying on the bottom by day – and in water warmer than you would normally target. Flasher and fly combos fished suspended off planer boards in the bottom 10 feet will sometimes pull big fish off the bottom.

Across much of the Great Lakes, the summer of 2013 featured unusually inconsistent chinook fishing. Most experts believe it was because water temperatures were in a range where fish could go almost anywhere, from top to bottom. Some of the season’s best action took place in late summer and lasted into October, with 1- to 3-year-old salmon putting on a steady bite.

“Weekenders” can take heart in knowing that even some veteran charter captains struggled to stay on the fish at times last year. Ever the optimists, longtime observers say such inconsistency is rare, and not likely to be repeated.

And while they’ll keep one eye on the temperature gauge this season, most also say hitting the exact temp is not nearly as important as a properly presented spread with a mix of planer boards, downriggers, and divers ahead of flasher/fly combos, spoons, and plugs.

After all, the sight of the first big-lake sunrise and the thrill of a screaming drag can make any angler forget last year fast!

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