Lake Erie and some of its denizens can both astonish and surprise even those who keep them close — perhaps especially those who keep them close.
Nearer from an organismic point of view than most to the enigmatic lake is Jeff Tyson, a Missourian who has worked as an Ohio Division of Wildlife fisheries biologist since 1994 and as Lake Erie fish management supervisor since 2013.
Two decades into a career spent studying the smallest, the warmest and the most meddled with of the Great Lakes, Tyson sometimes sounds more like an admirer than a scientist when pronouncing on what might remain the most biologically productive of the five.
“Lake Erie is still amazing to me,” he said.
What coaxed Tyson’s tribute last week were the findings about this year’s walleye hatch as ascertained by trawl surveys and subsequent number-crunching that concluded this month.
“Pretty decent for walleye, for sure,” Tyson said. “It’s the best hatch we’ve had since 2003, and a top-five hatch overall.”
The annual count goes back to 1987, late in the decade when the walleye population exploded and Lake Erie earned a reputation as the “walleye capital of the world.”
The brand didn’t seem at all hyperbolic when an estimated 100 million walleye saturated the lake and limit catches of 10 fish per day year-round didn’t seem extraordinary. For reasons not yet fully understood, the boom gave way to a long period of diminished returns.
Strong and successful walleye hatches occurred in 1994, 1999 and 2003, the latter among the best on record. The years since have been remarkable mostly for their run of mediocrity, as models indicate the walleye population comprising fish age 2 and older has slipped to some 24 million, a fraction of the number from 10 years before.
The 2015 hatch, however, should be a game-changer, at least for a while.
“This seems similar to the ’94 hatch,” Tyson said, “though we can’t put it into any kind of context yet.”
It will be two years before the 2015 hatch has any impact on sport fishing, though its influence will continue for a decade and longer. As for what happened to the 1994 class, Tyson said that hatch added some 20 million walleyes to the catchable fish population after two growing seasons.
When Tyson was asked what made a difference between this year’s successful walleye hatch and so many of its predecessors, he offered a one-word answer: “Winter.”
Gaining acceptance is the notion that Lake Erie walleyes best produce offspring after cold winters that allow the lake’s surface to freeze for a substantial time.
To be sure, the 2013-14 winter was colder and ice cover lasted longer than during the winter just past, yet its results were closer to average than to spectacular.
So why the different results?
The difference between this year’s production and last, Tyson said, suggests a distinction between the number of walleyes that hatch and the number that make it through a gauntlet of conditions that affect survival after the hatch. Those includes the levels of phosphorous, nitrogen and suspended silt resulting from spring and summer runoff, storms and water current, predation by competing species and, to some extent, the intensity of toxic algae blooms.
Despite consecutive winters during which Lake Erie’s surface froze, ice cover becomes less likely as the climate warms, meaning strong hatches might not occur with regularity. That doesn’t necessarily spell doom for walleyes, though it’s a cool-water species, as long as the lake is made fish-friendly enough to allow the young walleyes to survive when strong hatches do occur.
“One thing climate change means is a lot of variability,” Tyson said, meaning cold winters simply won’t disappear despite increasing global temperatures.
However, they and those big walleye hatches might be farther between.
outdoors@dispatch.com
