Points North: A Hot Summer for Lake Superior Fishing

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Trollers take note. This summer is shaping up to be a good one for Lake Superior fishing. Last week, I was emailed photographs of some sizeable Chinook salmon—like in the 6- to 10-pound range—caught in Lake County. Other good reports have been coming in as well—even on my boat.

While the North Shore can be counted on for good fishing, the action is starting a little earlier this year. The reason? Unusually warm weather, beginning last spring, has taken some of the chill out of Superior’s icy-cold water. In Duluth, people are going swimming—and not just those with the fortitude of a polar bear. The water, as they say, is fine.

Make no mistake; Lake Superior hasn’t suddenly become the world’s largest swimming pool. The surface water temperature was a balmy 47 degrees when I went out shortly after dawn this morning. However, surface water temperatures are warmer than they ought to be at this time of year, due the effects of an El Nino event in the Pacific Ocean. The lake had very little ice cover last winter, which accelerates the annual spring-summer warm-up.

Recently, researchers at the Large Lakes Observatory at the University of Minnesota, Duluth, predicted surface waters will be exceptionally warm by mid-August, perhaps higher than the 68 degrees reached during an El Nino event in 1998. The average August surface temperature is 59
degrees, which has already been recorded this year by a NOAA buoy northwest of Wisconsin’s Apostle Islands.

In a telephone interview, Jay Austin, associate professor of physics, says scientists cannot draw conclusions based upon lake temperatures for one year, but the warming temps correlate with a trend that’s been occurring for several decades. Other researchers have noted less winter ice during the same time frame. Ever so slowly, Lake Superior seems to be warming up.

If the trend continues, what this warm up may mean over coming decades is largely a matter of speculation, scientific or otherwise. What it likely means for this summer is good fishing. Generally, warmer waters seem to promote more growth for Pacific salmon, both Chinook and Coho. While native lake trout can live for decades, the life cycle of Pacific salmon spans just a few years—of which just a few months are growing seasons.

After leaving the tributary streams where they spend the first year of life, salmon migrate to the big lake to feed and grow. Unlike cold-loving lake trout, salmon prefer water a few degrees warmer. When conditions are favorable, such as this summer, they can pack on extra pounds. While you are unlikely to connect with Chinooks as big as the 20-pound-plus whoppers they catch in always warmer waters of Lake Michigan, fish in the 10-pound range may be possible later this summer.

By contrast, Coho salmon generally run in the pound-and-a-half to three-pound range. While they may run a little bigger, whoppers are unlikely. Coho population also vary in abundance from year to year, more so than Chinooks, which means fishing for them may be less noticeably affected by a hot summer.

Just how much North Shore fishing success reflects the warmer surface water temperatures will depend on summer weather. Generally, prevailing northwest winds blow the warm water offshore and upwelling cold water from Superior’s depths replaces it. Onshore winds push the warm surface layer back to shore—establishing a pattern that repeats itself every time a front passes through the region. This means that even at the height of the August dog days, you can find very cold water along the North Shore. And when you do, the fish, at least ones that want to bite, seem to be somewhere else.

The flip side is that during the dog days the surface water may become so tepid trout and salmon retreat to unfishable depths, a situation that occurred during a hot summer about five years ago. If so, it will take the inevitable winds of September to begin stirring up the water and dispersing the warmth, a process that occurs every autumn. In fact, regardless what happens in August, fishing should be excellent during September this year.

Fishing should be fine until the dog days arrive as well. Right now, trollers are finding good fishing all along the upper two thirds of Minnesota’s North Shore. Expect the action to continue at least until early August. That said, trollers who plan to compete in the Silver Bay Salmon Classic this weekend (July 17-18) or Buck’s Fishing Contest in Grand Marais (July 31-Aug. 7) stand a better than average chance of landing something worthy of a weigh-in. But whether or not you plan to compete, this summer is a great time to experience Lake Superior fishing.

Airdate: July 16, 2010

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