The shovelnose sturgeon, which inhabits the Missouri and Yellowstone drainages, has been proposed for listing as a threatened species even though it's still plentiful.

The U.S. Fish and Wildlife Service announced its proposal last week, citing as a reason the fish's similarity to the endangered pallid sturgeon, which was listed in 1990. The ruling mainly affects commercial harvest of the fish, which is valued for its roe, sold as caviar. The listing would make allowances for noncommercial harvest under applicable state laws. Recreational anglers in Montana would be allowed to keep shovelnose sturgeon even if the fish is listed as a threatened species.

"We've been documenting the take of pallid sturgeon incidentally when fishing for shovelnose," said Diane Katzenberger of the Fish and Wildlife Service's Denver office. "This is all about conservation of the pallid sturgeon, which we've been working on for quite a while."

Limited effect

Fewer than 40 commercial harvesters are expected to be affected if the listing is approved.But the change could have a big effect on pallid sturgeon survival.

The Fish and Wildlife Service estimates that,where shovelnose sturgeon are commercially harvested, pallid sturgeon mortality is about three times higher.

Although scientists have known since the early 1900s that pallid and shovelnose sturgeon are separate, similar-looking species, it has been only in recent years that enough data has been collected by state fishery agencies to document the threat from commercial fishing, said George Jordan, a fisheries biologist with the Fish and Wildlife Service in Montana.

Shovelnose wouldn't be the first species to be listed just because it resembles an endangered species. Five others, including the American alligator and Florida puma, have been listed to prevent incidental harvest in certain areas.

Caviar sought

The shovelnose sturgeon is valued for its roe, known as hackleback caviar.

One Web site listed the roe at $18.50 an ounce.

Four states - Missouri, Illinois, Tennessee and Kentucky - allow commercial fishing for shovelnose sturgeon. But the federal listing would affect only those rivers where pallid sturgeon and shovelnose populations overlap.

Although Montana's Missouri and Yellowstone rivers have no commercial shovelnose fishery, they are included in the rule to prevent the movement of the commercial fishery to the state if it is shut down elsewhere. The Missouri and Yellowstone are also home to the endangered pallid sturgeon.

Mississippi fish

Historically, shovelnose sturgeon were found throughout much of the Mississippi watershed, including its main tributaries. As is the case with many species, dams and the alteration of rivers for shipping and flood control reduced the amount of habitat for the fish.

In Montana, the fish range from the North Dakota border up the Missouri River to Great Falls, in addition to the Marias and Milk river tributaries. On the Yellowstone, the fish ranges upstream from the North Dakota border to about Forsyth, as well as the Tongue and Powder rivers.

While these are the main areas the fish occupy, a shovelnose sturgeon was caught on the Yellowstone River near Park City in 2007. The Marias, Tongue and Powder rivers are considered important to the fish for spawning, which occurs between May and early June.

The shovelnose is the smallest of North America's sturgeon species. A mature female shovelnose, more than 7 years old, weighs only about 2 to 3 pounds and measures 18 inches to 2 feet long. The largest ever recorded weighed 18 pounds and measured about 3.5 feet.

Much like their cousins, the shovelnose has a prehistoric appearance with a long, flat snout with whiskerlike barbels extending down in front of its mouth. They are mainly bottom feeders, dining on small crustaceans, baitfish and nymphs. Their ribbed back is grayish; their undersides are white. The tail is somewhat sharklike in appearance. They favor fast-flowing, turbid water.

Montana is home to only three sturgeon species, including the white sturgeon, which is found only in the Kootenai River. The white and pallid sturgeon are listed as species of concern in the state.

Doing well

Populations of shovelnose sturgeon in Montana are doing well, according to research by Montana Fish, Wildlife and Parks.

"The trend data indicates they're abundant and fairly darn common," Jordan said.

Pallid sturgeon are a different story. Their population in Montana is estimated at between 130 to 190 wild adult fish. There has been no documentation of wild reproduction.

"They may be spawning, but those fish aren't surviving," Jordan said.

The Fish and Wildlife Service will accept comments and scientific information regarding its proposal until Nov. 23. Recreational anglers in Montana would be allowed to keep shovelnose sturgeon even if the fish is listed as a threatened species. The listing would make allowances for noncommercial harvest under applicable state laws.

Contact Brett French at french@billingsgazette.com or at 657-1387.