Pandora's Locks: The Opening of the Great Lakes-St. Lawrence Seaway

17/ PARADOX

231 231 Who gets to decide what is a good fishery and what isn’t a good fishery? —Jim Seelye, retired U.S. Fish and Wildlife Service fishery biologist, 2008 17 PARADOX B iologist Tammy Newcomb stood before a large group of anglers at a fisheries workshop in Michigan and asked a most provocative question: Was the changing character of Lake Huron’s fishery in a state of pandemonium or promise? The response from the crowd of charter-boat captains and master anglers? Silence. No one dared to venture a guess as to which scenario most accurately described the hurricane of ecological changes swirling in the third largest of the five Great Lakes. The year was 2008. Over the course of a decade, a confluence of human-induced events—overstocking of salmon, decreased quantities of prey fish, zebra and quagga mussels hogging fish food—conspired to turn Lake Huron’s fishery on its head. 232 C H A P T E R 1 7 232 The lake’s thriving salmon fishery produced record catches in 2002, only to collapse the following year. Alewife, the invasive fish that supported the salmon fishery, vanished from the lake. That was bad for salmon but good for native fish species, including walleye, lake trout, and emerald shiners. Walleye made a dramatic recovery in the absence of alewife, and lake trout were showing signs of making a comeback. But the total volume of prey fish in the lake was dropping like a lead sinker, as was the abundance of Diporeia, an amphipod that was the most important source of fish food in the lake. Confounding the situation was the conquest of the lake bottom by zebra and quagga mussels, which injected unprecedented chaos into the ecosystem. The mussels increased biological productivity near the shoreline, but left deeper areas of the lake devoid of aquatic life. Dreissena mussels transformed Lake Huron into a mirror image of Lake Superior, which had strikingly clear water but supported far less fish than its sister lakes to the south. So what was the state of Huron’s fishery: pandemonium or promise? The answer depended on your perspective. Newcomb said there was a fair amount of both. Lake Huron, she told the anglers, faced “wickedly complex ecological resource issues.” The operative word was complex. The lake’s ecosystem was changing faster than the experts had believed possible. “Change is inherent in natural systems,” Newcomb said. “What’s surprising to us as managers is the rate of change in Lake Huron.”1 I posed Newcomb’s perplexing question to one of her peers at the fisheries workshop, which was held in the Fraternal Order of Eagles Lodge in Alpena, Michigan. Jim Johnson was a longtime fisheries biologist for the state of Michigan; he had spent most of his career studying Lake Huron’s fishery. Much of Johnson’s work in the first decade of the twenty-first century focused on finding new ways to manage fisheries in the face of an onslaught of foreign species that rewired the lake’s ecosystem. “Lake Huron is not the same lake we knew just 10 years ago,” Johnson said. “From the standpoint of the fishery in Lake Huron, I’d say we’ve experienced tradeoffs. Because invasive species contributed to the collapse of alewives, we’ve experienced a major rebound in two native species, lake trout and walleye. That’s a good thing, but it’s happening for the wrong reasons.”2 Lake Huron was reverting to its presettlement condition, when native fish species were dominant and the water was clearer and cleaner. Its ecosystem was drifting away from the glorified fish farm Huron had become in the 233 233 David Jude, University of Michigan, School of Natural Resources and Environment David Jude, University of Michigan, School of Natural Resources and Environment John Lyons, Wisconsin Department of Natural Resources This emaciated Chinook salmon was caught in Lake Huron in 2005. The lake’s salmon fishery was decimated by the disappearance of alewives, which was caused by overstocking of salmon and the invasion of foreign mussels that disrupted the fish food chain. As Lake Huron’s imported salmon fishery collapsed, some native fish species rebounded. Shown here are walleye, which made a dramatic recovery after alewives virtually disappeared from the lake. 234 C H A P T E R 1 7 234 1960s, when Michigan imported a salmon fishery to rein in...