Nov. 5, 2012
By Aaron R. Conklin
Location’s an important concept in real estate, but it matters a lot with fish, plant and animal species as well. Take the largemouth bass, for instance: In the Midwest, the largemouth is immensely popular, the centerpiece of the booming sports fishery scene. West of the Rocky Mountains, it’s an invasive predator, gobbling up native species and disrupting the local food web.
Communities that have to deal with the unexpected ecological ramifications of these unwanted visitors tend to refer to them as “invasive species.” While it’s a technically accurate term, Phil Moy, University of Wisconsin Sea Grant Institute’s assistant director for research, prefers to think of them as “species out of place.”
It’s a distinction that hit home again for Moy on a recent trip to Alaska, where he found himself in conversation with a local shop owner. The woman asked him what he did and why he was in town. When he mentioned “invasive species,” her eyes lit up.
“Oh, I know about that,” she said. “Northern pike are a real problem up here.”
And it’s true. Northern pike, which are not native to Alaska’s particular part of “north,” are ravaging trout populations in Alaska’s streams, and they’ve overrun the Susitna Basin and infested Stormy Lake on the Kenai Peninsula. In September, Alaska’s Department of Fish and Game resorted to deploying a poison to decrease the pike population in the lake. Here in Wisconsin, pike, like largemouth bass, are an important strand in both the food web and the sports fishing universe. In Green Bay, the pike are struggling to spawn and maintain numbers, hampered by low water levels in the Great Lakes and dams that have disrupted their habitat.
“In Alaska, they actually have bounties on northern pike—they want anglers to come in and take them out, kill as many as they can,” said Moy.
Yellow perch, the staple of Friday night fish fries across Wisconsin, are also considered an undesirable fish in Alaskan waters, eating competing species, in a place it was never originally intended to be. Another species out of place.
“A lot of our invasive species in Wisconsin have a home somewhere else in this world, but for whatever reason, they’ve been introduced here, for fish farming, sports and recreational fishing or some other reason,” said Moy. “And then they become a problem. As what’s happening both in Wisconsin and Alaska shows, a well-intentioned introduction can really go awry if it’s not well managed. Or if it gets loose and manages to establish itself and reproduce.”
The effects of these well-intentioned transfers and releases can be long-lasting…and devastating. Moy points to the introduction of smelt into Sparkling Lake in Northern Wisconsin. The smelt, a popular forage fish in Lake Michigan, probably seemed like an attractive choice for anglers who enjoyed harvesting them in other lakes during spring spawning season. But now, as a consequence of their introduction in Sparkling Lake, the walleye fishery that was self-sustaining for so many generations is now failing and must be supported through annual stocking. And, the walleye in Sparkling Lake have also been devastated by the introduction of yet another species out of place—the rusty crayfish.
In Wisconsin, Asian carp and round goby get most of the invasive species headlines, but monitors are on the lookout for several species that don’t belong in the Midwest but could potentially thrive and become problematic here if accidentally (or purposefully) introduced. Species like monkey goby and blue-back herring.
In the end, it comes back to a message of simple prevention. “Threats like these are all really good reasons not to move species around,“ Moy said. “Don’t move live bait from one body to another, don’t move species, and be sure you’re cleaning your boats.”