We are all too familiar with stories of invasive and nonnative species that persistently show up in our environment, causing ecological harm and creating competition for our own native species. Most invasives are the result of globalization, having hitchhiked their way here from foreign shores aboard cargo ships and in untreated ballast water. Species like the emerald ash borer and zebra mussel come to mind. But other nonnative introductions have been caused by the hand of man—sometimes carelessly inadvertent and at other times calculated and intentional.
An example of inadvertent species introduction would be dumping a bait bucket into the water after a day of fishing. That’s how nonnative alewives ended up in many of the Finger Lakes and now compete with native rainbow smelt for forage. In contrast, an intentional introduction would be a science-based fisheries management program wherein—after intense study and stakeholder input—species like brown and rainbow trout or nonnative salmon are stocked in waters deemed to be suitable and where compatibility with existing native species is not an issue. Brown trout and rainbow trout are examples of nonnative species that currently thrive in New York waters.
The New York State Department of Environmental Conservation recently confirmed the discovery of walleyes in Skaneateles Lake—a pristine Finger Lake best known for its excellent trout and salmon fishery. It is one of only two dozen water bodies in the entire state that supports good populations of landlocked Atlantic salmon. The DEC began stocking salmon there more than 50 years ago and because natural spawning is unsuccessful, the agency continues to stock the lake with 9,000 landlocked salmon annually—along with 20,000 rainbow trout as well.
Two questions come into play here. The first is: How did walleyes get into Skaneateles Lake? One possibility is that they’ve always been there in undetectable numbers and, if so, changes in the lake’s ecology could be making it more hospitable to walleye reproduction. Another is that they were purposely introduced by someone who has a preference for catching walleyes—a practice that I call “bucket biology”.
The second question is this: What is the harm? Walleyes have never been known to inhabit Skaneateles Lake. However, unconfirmed reports of walleye catches began circulating several years ago. A recent DEC netting operation—the first there since 2012—confirmed that indeed, there is a thriving walleye population in the lake. These aggressive toothy predators, which are large members of the perch family, are known to feed on salmon and trout fingerlings—the very sizes stocked by the DEC.
The answer to the second question is trickier and will depend on longer-term observation by fisheries managers. But I do have an analogy: In the 1970s, I was director of fish and wildlife management at Whitney Park, a 68,000-acre private timberland in the central Adirondacks. Its 77-mile boundary line encompassed 42 lakes and ponds, which included Little Tupper Lake—a 5-mile-long body of water that harbors a genetically-unique strain of brook trout that had been isolated in that watershed by glacial recession 12,000 years ago. When I worked there, trophy-sized Little Tupper Lake Strain Brook Trout exceeding 20 inches and weighing up to 3 pounds were common.
In 1997, after successfully preventing the introduction of nonnative fish species into Little Tupper Lake for 100 years, Whitney Industries Inc. sold a large portion of its holdings to New York State, which included Little Tupper Lake. Today that tract of land is known as the William C. Whitney Wilderness Area and is open to the public. Soon after, someone covertly introduced largemouth bass into the lake—perhaps in contempt for the state’s restrictive policies intended to continue preserving the unique heritage strain. As a result, the bass have overtaken the lake and catching any kind of trophy brook trout there is a thing of the past.
The fact that walleyes now inhabit Skaneateles Lake could seriously impact its trout and salmon fishery as well. DEC fisheries managers are convinced that walleyes were illegally stocked—yet another example of amateur bucket biology. They’re also convinced that walleyes are there to stay. Whether or not Skaneateles ever becomes a good walleye fishery has yet to be determined. But the real question is this: What’s the outlook for the rainbow trout and landlocked salmon fishery now that a new aggressive predator fish has been introduced? Only time will tell.