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Discovering the Sculpin

April 22, 2011 | by Diane Tipton

Mottled sculpin on the Big Hole River tributaries.
These sculpin can be found on Meadow and
Swamp Creek among other locations.

David Schmetterling, a Montana Fish, Wildlife & Parks fisheries biologist in Missoula, has already spent 11 years studying a small bodied, nongame fish—the sculpin—and he's hooked. If you're an angler you may be saying "what the heck?" But Schmetterling and other FWP fisheries folks recognize the well being of the state's trout is closely linked to the well being of its sculpin.

Sculpin in Montana occupy cobble and gravel riffles of fast moving, cold water streams and rivers as well as lakes, though the majority of sculpin species in the Cottidae family live in salt water.

"Montana's sculpin are inconspicuous, bottom-dwelling fish that grow to about six inches in length at maturity," Schmetterling said.

"With their abundance and small body size, sculpin are a critical food for sport fish, birds, reptiles and mammals and a good indicator of the overall health of the aquatic system—yet we know very little about them," he said.

Schmetterling, Susie Adams, a U.S. Forest Service research biologist in Mississippi; Mike Young of the Rocky Mountain Research Station; and David Neely, then a researcher at Saint Louis University in St. Louis; collaborated on research to fill this gap.

"Sculpin were so common 40 years ago in our streams, rivers and lakes that no one thought to study them," Schmetterling said. "Now, even with limited data, we can see they aren't present in some places where they were once documented, and overall their numbers are declining."

No one knows the extent of these changes or how they affect trout and other water-related species—for example, kingfishers, herons or garter snakes.

To begin acquiring the necessary data, the team studied sculpins' movements at Milltown Dam and in Chamberlain Creek, a tributary to the Blackfoot River, in 2000 and 2001. Characteristics, such as how much a species moves, are important clues for biologists trying to identify and observe a particular species.

"During research in Chamberlain Creek, we detected two distinct movement patterns. Some sculpin movements were extensive, for example, about 230 yards during one month in midsummer, the most ever  recorded at that time," Schmetterling said. "This was odd because the sculpin we thought we were observing, the slimy sculpin, is sedentary."

With the help of DNA analysis, they identified the presence of two species, where only one was thought to have been. The 'Rocky Mountain sculpin' were the 'movers.'

Following this research, the team went on to search for sculpin in dozens of streams between 2006 and 2010.

Neely showed through DNA work that what is known as the Columbia slimy sculpin  found west of the Continental Divide is more closely related to a Russian sculpin in Siberia—not the slimy sculpin of the eastern U.S., as some previously thought.

DNA analysis by Young at the Rocky Mountain Research Station suggested that Rocky Mountain sculpin found west of the Continental Divide are native to that area, not the result of introductions earlier, when it was legal to use sculpin as bait fish.

As a result of the team's work, three sculpin species—the Columbia slimy sculpin, the Rocky Mountain sculpin, and a species found in the St. Regis River drainage, will be described and renamed soon in a published, peer-reviewed paper using formal scientific guidelines.

"Our knowledge of sculpin is growing, and that knowledge will be a tool we can use to better assess the overall health of aquatic systems in the state," Schmetterling said.

The 2011 Montana Fishing Regulations feature sculpin on the back cover. With fishing on Montana's rivers and streams opening May 21, now is a good time to pick up a copy of the regulations. For more on all of Montana's fish and wildlife species, visit the Montana Field Guide.