DNR keeps watch on vulnerable river species

DNR keeps watch on vulnerable river species.

MOUNT VERNON - State fisheries biologists are keeping a close eye on a strange and little-known Cedar River denizen - the shovelnose sturgeon.

Increasing worldwide demand for caviar - sturgeon eggs - and accompanying high prices have encouraged illegal commercial exploitation and population declines of several species, according to Joe Larscheid, chief of the Department of Natural Resources Fisheries Bureau.

“The high price of caviar is a concern. That's why we are working hard to stay on top of the situation with population monitoring efforts,” said Larscheid, who was at Palisades-Kepler State Park on Wednesday to help biologists capture and tag shovelnose sturgeon as part of an ongoing tracking study.

Larscheid said the shovelnose is the smallest species of sturgeon and the last to be targeted by roe collectors. “But every sturgeon population they have gone after has crashed,” Larscheid said.

Crews using both trammel nets and electroshock units captured about 750 sturgeon during three days of sampling that ended Wednesday. The fish were measured, tagged and returned to the Cedar, where they will spawn on sand and gravel bars when the water temperature reaches the 60-to-65-degree range.

The 100 miles of Cedar River below the 5-in-1 dam in Cedar Rapids - one of the longest free-flowing river stretches in Iowa - is an important part of shovelnose habitat, according to DNR fisheries research biologist Kirk Hansen, who coordinated the collection effort.

While the lower Cedar has a resident sturgeon population, about 90 percent of the shovelnose there now have migrated from the Mississippi River to spawn, Hansen said.

Shovelnose sturgeon also live below the last dams on other Mississippi tributaries in Iowa, including the Des Moines and the Maquoketa, he said.

Cedar River sturgeon monitoring, which began in 2006, indicates that populations are stable, according to Hansen.

For Iowa's recreational anglers, there is no closed season and no bag or possession limit on shovelnose sturgeon, which are considered excellent table fare when smoked.

“We think they are an underutilized resource for recreational anglers,” Larscheid said.

Recreational sturgeon angling generally occurs in April and May, when the shovelheads are most abundant in rivers like the Cedar.

For commercial fishermen, who are subject to more regulations, Iowa has imposed a 27-inch minimum size limit (from the tip of the snout to the fork of the tail) to ensure that shovelnose sturgeon reach sexual maturity and are able to spawn before they are harvested.

Hansen said sturgeon are particularly vulnerable to overharvest because of their slow rates of growth, their late maturity, their inconsistent reproduction and the high value placed on egg-bearing females.

Caviar prices have skyrocketed in recent years following the collapse of the beluga sturgeon population in the Caspian and Black seas of southwest Asia. With the highly prized beluga caviar virtually off the market, roe collectors have turned to other less desirable but still valuable species.

The beluga sturgeon, which can weigh more than a ton, dwarfs the shovelnose sturgeon, which tops out around 8 pounds.

An 8-pound egg-laden shovelnose could bring as much as $100, according to DNR fisheries biologist Bernie Schonhoff.

Sturgeons have elongated bodies protected by sharp-edge bony plates called scutes rather than scales. Bottom feeders, they use their four dangling barbels to detect aquatic animals, which they ingest through an extendible toothless mouth.

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