A living fossil fights for survival.

Some call the pallid sturgeon (Scaphirhynchus albus) a living fossil. This large fish arose in the Cenozoic Era like a dinosaur, then survived the cold crunch of advancing glaciers and lived to thrive in the big, muddy rivers of middle North America. Only recently has the pallid sturgeon experienced changes so extreme as to threaten its survival. In a century's time, habitat destruction, pollution, dams, changes in river flows, over-fishing, the caviar trade, and hybridization in the Missouri River basin drove the pallid sturgeon to the brink of extinction.

The pallid sturgeon's life characteristics--a long life and slow growth--may contribute to its decline. This fish grows to a size of more than five feet (1.5 meters) and 80 pounds (36 kilograms), and it lives beyond 60 years. But maturity comes slow; it takes females a decade to ripen, and even under ideal conditions, spawning is sporadic and infrequent, perhaps every other year.

[ILLUSTRATION OMITTED]

The Fish and Wildlife Service listed the pallid sturgeon as an endangered species in 1990. Since then, natural resource agencies, governments and citizens from Louisiana to Montana have joined forces to recover this ancient fish. The Neosho National Fish Hatchery in Missouri is one of six federal and state hatcheries raising pallid sturgeon for stocking into the Missouri River.

Only in its fifth year of raising pallid sturgeon, Neosho NFH continues to increase its production from wild-caught fish, both by refining culture techniques and increasing the amount of tank space. Like most pallid sturgeon raised at hatcheries, the fish receive either a colored latex tag or coded wire tag along with an individually numbered PIT (passive integrated transponder) tag before stocking. This helps biologists distinguish between wild and hatchery-raised pallid sturgeon, yielding a better understanding of the species in the wild.

"The Middle Basin Workgroup determines how many fish we produce; they set the stocking goal," says Neosho's manager, David Hendrix. "The Service's Columbia Fishery Resources Office in Missouri does the follow-up on survival, and those tags in the fish tell us where they came from. The hatcheries are a management tool to keep the fish from going extinct."

In 2004, Neosho's original sturgeon building was expanded through a partnership with the Army Corps of Engineers. This addition allows the hatchery to spawn and rear an estimated 4,000 pallid sturgeon each year. A building tinder construction will allow the facility to produce another 10,000 fish per year. The expanded Neosho facility will prove vital in rearing pallid sturgeon, as will the Corps-funded renovation of hatcheries like Miles City State Fish Hatchery in Montana, Gavins Point NFH in South Dakota, and the Blind Pony State Fish Hatchery in Missouri, all of which have expanded to stock pallid sturgeon.

Over 150,000 pallid sturgeon have been stocked since the fish was listed. The efforts to raise pallid sturgeon are the result of cooperation between the Corps and Service to bring the Corps's federal projects into compliance with the Endangered Species Act. "We are committed to protection and recovery of threatened and endangered species like pallid sturgeon," says Brigadier General Gregg Martin, Northwestern Division Commander.

[ILLUSTRATION OMITTED]

At the lower end of the species' natural range, biologists at Natchitoches NFH in Louisiana have spawned pallid sturgeon for release in the Mississippi River. They stocked nearly 12,000 fish in autumn 2004. No pallid sturgeon have been stocked there since 2004 because biologists believe the fish is doing well enough in the lower basin; these fish tend to grow faster due to warmer temperatures, thus reaching maturity sooner. Assistant Hatchery Manager Dr. Jan Dean continues to advance our understanding of the fish by creating a larval identification series, which allows hatchery and field biologists to identify pallid sturgeon in their rapidly changing early-life forms and distinguish them from the more common shovelnose sturgeon (Scaphirhynchus platorynchus). Dean is also on the leading edge of research with the Service's Jackson, Mississippi, Ecological Services Field Office to study fish movement in the wild. And move they do; one of the fish recently caught by Dean and Paul Hartfield of the Jackson Office was spawned and tagged at the Blind Pony State Fish Hatchery, more than 300 miles (480 kilometers) away.

[ILLUSTRATION OMITTED]

Next up the Missouri River from Neosho is Gavins Point NFH in South Dakota. This hatchery also was retooled to handle pallid sturgeon. Hatchery Manager Herb Bollig and crew have been spawning pallid sturgeon since the early 1990s. The facility houses the only pallid sturgeon brood stock in the world: 10 year-classes of 88 families, comprising thousands of fish. They are still immature, and Bollig expects a few more years to pass before they start producing eggs. With so few wild fish left in the Missouri River, this brood stock is critical to the species' survival. Inspections by Service biologists at the Fish Health Center in Bozeman, Montana, lend an extra level of security, ensuring that the brood stock remains robust. A new well coming online should ensure the fish get disease-free water.

Farther upstream, wild adult pallid sturgeon are brought to Garrison Dam NFH in North Dakota, spawned, and returned to the wild. Some of the wild adults get a radio transmitter surgically implanted so management biologists can learn more about habits and habitats. Their offspring are eventually released into the Missouri River as well. Hatchery Manager Rob Holm says the adults in the wild are getting old. Some fish that have been caught over time have lost weight, underscoring the need for maintaining a captive brood stock. But the problem for pallids remains one of habitat. Captive propagation and milt (fish sperm) preservation only buy some time to fix habitat problems, says Hohm. "Our milt cryopreservation repository captures the existing genetic makeup of the species," Holm says. "If the necessary habitat changes can be made in the next 50 years to facilitate recovery, we want as genetically a diverse group of sturgeon as possible to release back into the wild, and the National Fish Hatchery System makes this possible."

Yvette Converse, Assistant Director of the Bozeman Fish Technology Center in Montana, agrees on the need to address habitat: "In the long-term, we don't want to be dependent on hatcheries for recovery, but want to have the habitat suitable for fish survival in the wild, and that may take decades. Water management may be the biggest obstacle for pallid sturgeon recovery." In the meantime, the Bozeman Center has expertise to offer. Physiologist Dr. Molly Webb has conducted blood assays, using blood chemistry and hormones to identify an optimal time to spawn fish. Those assays could ultimately mean less stress on an aging and obsolescent population of wild fish, as well as on captive stocks, and a greater yield of offspring. Biologist Kevin Kappenman conducts thermal studies, looking at egg maturation, hatching and larval rearing development with changing temperatures--information useful for better captive propagation.

Hatchery-raised pallid sturgeon released into the Missouri River now have a greater chance to find some of the shallow-water habitats that are critical for their survival. The Corps undertook an aggressive effort in 2004 to create an estimated 1,200 acres (485 hectares) of new habitat in the lower reaches of the Missouri, where habitat loss in the past has been so great. The Columbia Fishery Resources Office (FRO) monitors some of the newly created habitat to see if it is used by both wild and hatchery-raised pallid sturgeon. This information will help guide the designs of future habitat restorations and determine if a greater diversity of habitat types is necessary.

In addition to the habitat work, the Columbia FRO is responsible for pallid sturgeon recovery in some 300 miles of the Missouri River, stretching from Kansas City to St. Louis. Dr. Tracy Hill, Columbia's Project Leader, chairs the Middle Missouri River Basin Pallid Sturgeon Workgroup, a multi-stakeholder forum for coordinating conservation efforts, and is a member of the Pallid Sturgeon Recovery Team. The recovery team is making great strides in scientific and technological breakthroughs.

Since 1999, Columbia FRO biologists have managed to capture only 123 pallid sturgeon in the lower 200 miles (320 km) of the Missouri River. Seventy-four of those fish were produced by state and federal hatcheries. Forty-two fish had no tags and were thought to be wild fish. Seven others were of unknown origin but were suspected to have been stocked.

[ILLUSTRATION OMITTED]

An important milestone on the road to recovery occurred in 1999 when biologists from the Columbia FRO discovered a freshly hatched larval pallid sturgeon in the naturally formed Lisbon side chute of the Big Muddy National Fish and Wildlife Refuge. This is the only verified case of natural reproduction within the lower Missouri River in more than 50 years. The Lisbon chute, created during the great flood of 1993, has since been a hot spot for collecting pallids.

Columbia FRO collected 44 pallid sturgeon in 2005. However in 2006, it could collect only 21 fish despite a significant increase in the sampling effort. The 2006 results are vexing and perplexing, and they show there is still much to learn. A myriad of complications face this ancient and extremely rare fish. Success is incremental, on the river or in a hatchery.

Jeff M. Finley is a biologist in the Columbia FRO, and Craig Springer is a biologist in the Division of the National Fish Hatchery System in Albuquerque, New Mexico.