Sun, May 5, 2002
Smelt threaten walleye fishery
Unwitting anglers may be transmitting fish to deep lakes

By Jim Lee
Gannett Wisconsin Newspapers

WOODRUFF - A palate-pleasing fish is leaving a bad taste in northern Wisconsin waters.

Rainbow smelt have unexpectedly appeared in 21 lakes in Vilas, Forest, Florence, Bayfield and Barron counties in recent years, reports Stephen Gilbert, Department of Natural Resources fisheries biologist at Woodruff.

The arrival of this exotic species has had a devastating impact on walleye populations in several lakes, causing fisheries experts to ponder ways to control the unwelcome invader.

Smelt have been part of Great Lakes culture for so long, many Wisconsin residents consider it a native fish, Gilbert said.

The fact is, smelt are originally from the Atlantic Ocean and a few inland lakes in Maine. In 1912, smelt from a Maine lake were stocked in Crystal Lake, a small lake in Michigan's Lower Peninsula, and soon made their way into Lake Michigan.

"Smelt were first discovered in Wisconsin in Lake Michigan waters of Door County in 1928," Gilbert said. "They eventually moved into Lake Superior, too."

Smelt numbers in the Great Lakes quickly exploded, leading to commercial fishing in the 1930s, soon followed by spring beach parties and smelt fries for a public enamored of the flavorful, plentiful newcomer.

Smelt are silver-colored, minnow-like fish that can grow to 12 inches in length but typically reach 5 to 7 inches in inland lakes, according to Gilbert.

It is the public's love affair with smelt that worries Gilbert.

He believes smelt fishermen, either deliberately or unwittingly, are the cause of smelt outbreaks in inland lakes.

It has been surmised that the first smelt appeared in inland waters when an angler, fresh from a spring smelt netting trip to Lake Superior or Lake Michigan, dumped the entrails into an inland lake upon returning home and cleaning the catch.

The theory is that the fish-cleaning operation mixed spawn and sperm from the ripe smelt, thus fertilizing the mixture and setting the stage for hatching where conditions allowed.

Apparently suitable habitat is not difficult to find, as smelt continue to pop up in unexpected places.

Smelt appeared in Fence Lake in the 1980s and quickly produced a spring spawning run that attracted anglers who previously journeyed to Lake Superior to net smelt. For some fishermen, smelt netting on Fence Lake has already become an annual tradition.

About the same time smelt were found in Fence Lake, the walleye population in the lake began to decline.

"People aren't aware that smelt are an exotic species," Gilbert said. "They don't realize the harm they can do to a lake."
Gilbert has extensively studied the impact of smelt on Sparkling Lake, a 154-acre natural lake alongside Highway 52 about 10 miles north of Woodruff.

In 1981, a University of Wisconsin survey found no smelt in the lake and a healthy, naturally reproducing walleye population with all ages of fish present.

Smelt were discovered in the lake in 1982 and the walleye population steadily went downhill.

In an attempt to resuscitate the walleye population, the DNR tried stocking small fingerling walleye, but few of those fish survived. It is believed many of them fell prey to minnow-eating packs of smelt.

"The only walleyes we found were larger fish," Gilbert said. "There was no evidence of recruitment of younger fish."
Walleye appear extremely vulnerable to smelt for several reasons.

Adult smelt roam in large schools over open water areas, where they feed on minnows and aquatic insects. Newly hatched walleye fry also gravitate to open water, where they feed on plankton and other invertebrates and become prey for foraging smelt.

A similar fate befalls cisco fry. No cisco have been found in the lake for several years.

Newly hatched whitefish, lake trout and perch fry are also more susceptible to smelt predation than other species, such as bass and northern pike.
In an effort to restore walleye fisheries to lakes threatened by smelt, Gilbert said, the DNR is considering five options, including:
* Banning angler harvest of smelt on inland lakes in an effort to prevent people from transporting smelt to other lakes.

* Attempting to remove the smelt through netting and other means. "Such efforts have failed miserably when used on other species," Gilbert said.

* Increasing the number of fish that prey on smelt, such as stocking adult walleye in a lake for several years.

* Using chemical treatment that wipes out all fish in the lake. This method might work only in a lake with no inlets or outlets, such as Sparkling Lake, Gilbert said.

* Managing the lake for fish species other than walleye.

"Smallmouth bass are flourishing" in lakes where the walleye population has been reduced by smelt, Gilbert said.

Lake trout prefer the deep, cold water favored by smelt and also feed on smelt. They might be a suitable game fish species to introduce in some lakes, he said.

The best management option, obviously, is to prevent smelt from entering a lake in the first place.

"Once smelt are established in a lake, they are nearly impossible to remove," Gilbert said.