U.S. Fish and Wildlife Service: Searching for the Elusive Pallid Sturgeon

FT. SNELLING, Minn., Jan. 16 /PRNewswire/ -- The subject is the pallid sturgeon (Scaphirhynchus albus). It is a bizarre, prehistoric looking fish found in parts of the Missouri and Mississippi rivers. Scientists believe that its roots in these rivers extend back as much as 70 million years.

Modern-day
pallid sturgeons have been known to grow up to six feet and weigh as much as 80 pounds. They are an endangered species. The U.S. Fish and Wildlife

Service
is working with many partners to bring them back.

"The pallid sturgeon was first recognized as a species in 1905 and was listed as an endangered species in 1990," said Joanne Grady of the U.S. Fish and Wildlife Service's Fish and Wildlife Management Assistance Office (FWMAO) in Columbia, Mo. "It's an ancient fish species that evolved in turbid, free-flowing large rivers with braided channels, sandbars and extensive backwater habitats."

Grady, the Columbia FWMAO and their partners hope to halt and reverse declines in pallid sturgeon populations by conserving and restoring the fish's vital habitat on the Missouri River.

One initial part of that effort involves long-term monitoring of several sites on the Lower Missouri River to document impacts and benefits of Missouri River operations. Other groups helping in this work are the Nebraska Game and Fish Commission, the Iowa Department of Natural Resources and the Missouri Department of Conservation.

The data that is being collected will be an important component to state and federal decision-making regarding modifications to Missouri River operations, mitigation site development, habitat restoration and land acquisition.

As noted, the Missouri and Mississippi rivers historically provided ideal habitats for the species. However, in the Missouri and Mississippi rivers of today the fish face habitat alteration, modifications to the rivers' natural hydrography and hybridization of the species that has occurred with the shovelnose sturgeon.

"Our staff has worked for the last five years to document the occurrence and habitat preferences of pallid sturgeon," Grady said. "This includes a multi-state project to identify pallid sturgeon habitat and refine capture techniques and equipment for this uncommon fish."

From 1996 through 2000 the Columbia FWMAO worked with the states of Nebraska, Iowa and Missouri and Southern Illinois University to cooperatively sample pallid sturgeon in the Lower Missouri and Middle Mississippi rivers.

"Sturgeon had last been extensively sampled in the Lower Missouri and Middle Mississippi rivers in the late 1970s," Grady said. "In the recent study, sampling crews targeted river reaches in which historic pallid sturgeon catches were noted or in which juvenile pallid sturgeon stocked by Missouri Department of Conservation's Blind Pony Hatchery were recaptured."

During the sampling, seven presumed-wild pallid sturgeon and two hatchery- reared pallid sturgeon were collected in the Lower Missouri River. Eleven hatchery-reared pallid sturgeon and two presumed-wild fish were collected in the Middle Mississippi River.

"Sampling documented declines in pallid sturgeon numbers coupled with the increased hybridization rate," Grady said. "This indicates a need to step up efforts to benefit the species."

The most recent sample, when compared to earlier sampling, showed that the ratio of wild pallid sturgeon to all river sturgeon collected dropped from about 1 in about 400 in 1985, to 1 in nearly 650.

Seven pallid-shovelnose hybrids were collected in the Middle Mississippi River while 15 were collected in the Lower Missouri River. In this sampling, the rate of hybridization increased from 1 in 365 in the late 1970s to 1 in 235 in the 1990s.

But there were some slight indications that the pallid sturgeon might be holding its own in some areas of the rivers.

The first documented evidence of natural reproduction of the species in the lower Missouri River was collected in August 1998. Service staff collected three larval pallid sturgeon in an ongoing monitoring study of the Lisbon Bottoms Unit of the Big Muddy National Fish and Wildlife Refuge on the Lower Missouri River.

A total of 44 larval sturgeon were collected from 1997 through 2000 in a seven-mile stretch of the Missouri River. Three larval sturgeon were identified as pallid sturgeon, seven were identified as probably being pallid sturgeon, three as shovelnose sturgeon and 31 could not be determined if they were pallid or shovelnose.

"Our staff will continue work to provide the pallid sturgeon population information needed by Missouri River managers and policy makers over the next several years," Grady said. "These efforts we hope will lead to stronger pallid sturgeon populations and continued habitat conservation and restoration in our river systems."