Smallies Thrive/Harsh Waters of Northern Lake Michigan

[Lee Borgersen]

      Smallmouth Bass Thrive in Harsh Waters of Northern Lake Michigan



Wisconsin DNR biologists Bobbi Kolstad, left, and Emily Kurszewski transfer smallmouth bass from a Fyke net to a work boat holding tank.

Life’s never easy for smallmouth bass around Washington Island at the tip of Door County, Wisconsin, but this stalwart fish somehow weathers the toughest challenges Lake Michigan can summon.

At least that’s how things looked in late May as biologists from the state’s Department of Natural Resources conduct a formal checkup on this remote fish population for the first time since 1997. The crews caught smallmouths with Fyke nets at six locations in Detroit Harbor from May 13 through early June to help assess the population’s age and length composition.

After measuring each bass, collecting scales from specific-size fish, and clipping a corner of every tail to identify them as inspected, biologists returned the “bronze-backs” to the harbor. In the weeks ahead, they’ll examine the scales with a microscope to identify the fish’s age, and count growth rings much like those of tree stumps.

 
Captured smallmouth bass wait to be inspected, measured and marked by DNR biologists before being released into Detroit Harbor.

The DNR expected to conclude the survey in early June as the “smallies” finished spawning, abandoned their shallow-water spawning nests, and returned to deeper waters offshore. How well this year’s newborn smallmouths fare probably won’t be known until the next time the DNR conducts similar assessments in five to seven years.

On day 10 of the ongoing assessment, Washington Island’s smallmouths looked strong. On May 2, the crew examined more than 150 fish, most of which were in the 16- to 20-inch range, with a few weighing about five to six pounds.

“They look very healthy,” said Scott Hansen, the DNR’s Lake Michigan biologist in Sturgeon Bay. Hansen leads the study with help from DNR biologists like Emily Kurszewski and Bobbi Kolstad.

“Smallmouths up here are generally leaner than smallmouths in the Sturgeon Bay area, but the water and conditions around Washington Island are more harsh and less productive than those south of here,” Hansen said. “This is near the northern edge of the smallmouth’s range, so you expect them to be a bit more lean. They’re healthy, though. We’re finding very few lesions or signs of disease, but we’ve found a few with scars that could be from sea lampreys.”

To better appreciate the challenges smallmouths face around Washington Island, picture the limestone island as the tip of a 75-mile pier jutting into Lake Michigan. Other than Porte des Morts, the treacherous five-mile strait between Detroit Harbor and the northern tip of the Door County peninsula, Washington Island is surrounded by open water for about 15 miles to the west, 20 miles to the north, 60 miles to the east, and 240 miles due south.

In other words, these smallies live in the middle of the world’s sixth largest freshwater lake, surrounded by miles of cold, wind-driven water that often pounds ashore in six-foot waves. The rock, sand, and cobblestone bottom surrounding Washington Island is great habitat for smallmouths, but areas exposed to mighty waves offer little protection to the smallies’ eggs and fry.

That’s what makes Detroit Harbor and the island’s other inlets and bays attractive to spawning smallmouths. The protected areas give young smallmouths a good start, but once they venture outside its protection in the weeks that follow, they’re vulnerable to the elements and the lake’s many predators.

 
Scott Hansen, the DNR’s Lake Michigan biologist in Sturgeon Bay, records data as DNR biologists Bobbi Kolstad and Emily Kurszewski measure, inspect and mark smallmouth bass.

One of those potential predators is also credited as an energy-rich food source that grows big smallmouths. The round goby, which first showed up in the region in 2002 or 2003, most likely entered the Great Lakes in ballast water from ships traveling from Eastern Europe’s Black and Caspian seas.

Gobies can coat the bottom in some areas and consume every bass egg in the area. On the other hand, as growing smallmouths start preying on other fish, they feed readily on round gobies. In fact, fishermen report great success when using lures that imitate the goby.

“Round gobies are definitely a double-edged sword,” Hansen said. “They found a niche in these waters and really took off.”

The DNR has documented a growth spurt in smallmouths in recent years that coincides with the round goby’s arrival. Dave Boyarski, fisheries team supervisor in the DNR’s Sturgeon Bay office, said five-year-old smallmouths in the waters around Sturgeon Bay averaged 12 inches 20 years ago. In recent years, smallies that age average 14 inches.

Boyarski said raising the size limit from 12 inches to 14 inches also probably helped, as has the increased popularity of catch-and-release fishing, but the biggest factor was probably abundant gobies in the smallmouth’s diet.

“That’s our best theory for explaining the growth increase,” Boyarski said. “The goby really took hold in this area. Similar growth patterns in Lake Erie are also tied to round gobies.”

 
DNR biologist Emily Kurszewski and supervisor Scott Hansen collect data on a captured smallmouth bass.

Boyarski and Hansen don’t assume smallmouths around Washington Island will experience the same growth rates as those around Sturgeon Bay. The water is colder and less fertile, which slows growth. Therefore, while Sturgeon Bay is known to produce occasional eight-pound smallmouths, that might be asking too much of Washington Island.

Even so, the remote island offers world-class smallmouth fishing. Most anglers work the 15- to 30-foot depths after the season opens July 1 around Washington Island, but some find ways to catch them as deep as 80 feet.

“The cold water up here is good for salmon and trout, and we see some perch and northern pike, but a lot of people come up here for smallmouths,” Hansen said.

The last time the DNR surveyed Detroit Harbor was 1997. The crews caught nearly 1,600 smallmouths in late May and early June that year, and documented a wide variety of ages from four to 15 years old.

The agency hopes to create a rotation in which it surveys Detroit Harbor about every five to seven years, as well as more sites on the peninsula’s lake side.

“We’ve never formally sampled the Bailey’s Harbor and Moonlight Bay area,” Hansen said. “We’d also like to sample Ephraim and Sister Bay on the peninsula’s bay side, but those are tough areas to assess with nets because they’re so open and exposed.”


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