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Save Living Fossils Underwater

16:52PM Sep 23, 2008


The following story was written by a University of Missouri student as part of the 2007 Sonja Hillgren/Farm Journal Ag Journalism Field Reporting Institute. Learn more.
By Su Jing
Wearing waterproof neoprene hip waders, Jason Dattilo jumps from a monitoring motorboat onto a small island of mud near the shore of the Missouri River at Waverly, Mo. Struggling toward a trammel net in the water, he sometimes has to use his hands to pull one leg out before moving the other one because his waders keep getting stuck in the gooey mud. With the help of his colleagues, he hauls the trammel onto the island.
This recent scene may be novel and even funny to most people, but it has become a daily ritual for Dattilo, a resource science assistant with the Missouri Department of Conservation. His job is to monitor the fish resources, especially the pallid sturgeon, of the Missouri River.
By setting trammel nets in sloughs scientists with MDC intend to capture the pallid sturgeon and other fishes for sampling and recording. The muddy island is one of the sampling sites.
Their goal—like that of Chinese scientists half a world away—is to save endangered sturgeon species, which date back to the age of the dinosaurs and beyond.
Holding up the trammel by one hand, stretching the other hand into the net, Dattilo pulls a turtle out. He sets it free.
Tipping the net over with the help of his colleague, he pours all the remaining creatures into a plastic bucket. Out comes an arm-length fish with a pointed snout and a dozen tiny silver fish. But none of them is an adult sturgeon or a larval sturgeon.
He lays the fish on a scale and notes their lengths. These will be the only fish he will catch today.
This is just a typical day for Dattilo, who has worked four days a week on the river for the last one and a half years.
"I have only seen the pallid sturgeon five times," he says.

Dinosaur of the Missouri

On the U.S. Fish and Wildlife Service website the pallid sturgeon is called a "Dinosaur of the Missouri," although whether for its age or its appearance is a tossup.
The pallid sturgeon looks more at home in a natural history museum than on the end of a fisherman's line. It has a flattened shovel-shaped nose; long, fleshy whisker-like barbells; a knobby back; and a long reptile-like tail. Rather than scales, it is armored with bony plates inside its gray skin.
The skin color is what distinguishes the pallid sturgeon from the shovelnose sturgeon. "They are similar, but the pallid is light tan or white in color," said Dattilo.
This unusual native of the Missouri and Mississippi rivers evolved from a group of fishes dominant during the late Cretaceous period 70 million years ago, when dinosaurs roamed the earth. It even looks like a dinosaur.
The pallid sturgeon is one of the largest fish found in these rivers. The fish has been documented weighing more than 80 pounds and reaching lengths of six feet. It was harvested for flesh and caviar, like the beluga sturgeon in the Caspian Sea, until it was listed as federal endangered species in 1990, according to the USFWS's website.

Endangered Status

No wonder Dattilo only has seen the pallid sturgeon five times in 18 months. The "dinosaurs" are now infrequent inhabitants of the Missouri River.
Pallid sturgeons were not identified as a separate species until 1905. Because of that historical data are rare. But catch records indicate that they were common as late as the 1950s and 1960s. After that, the observation data from the Missouri River and its tributaries in the Dakotas and Montana reflect the downward trend of population.
In the Dakotas scientists observed an average of 50 pallid sturgeon a year in the 1960s, 21 a year in the 1970s and six a year in the 1980s, according to the Pallid Sturgeon Recovery Plan released by USFWS in 1993.
Scientists estimated in 1996 that the total population of pallid sturgeon was as few as 6,000 to as many as 21,000 throughout its entire range.

Reasons for Decline

Caviar consumption is thought to be one of the reasons contributing to the decline of the pallid sturgeon. But commercial catch records have dropped substantially since record keeping began in the late 1800s, especially since the fish was listed as the endangered in 1990, according to the recovery plan. Since then the pallid sturgeon has been protected by law from being killed, harmed or harassed.
Water pollution is also a likely threat to the fish over much of its range. Scientists suspect that organic wastes from towns, packing houses and stockyards and a variety of pollutants from industries along the Missouri River may affect the reproductive cycle of the pallid sturgeon, affecting developing eggs, the development of embryos or the survival of fry. This reduces reproductive success.
Further investigations are needed to assess the role of contaminants in the decline of pallid sturgeon populations, the recovery plan suggested.
But the primary reason for their decline is believed to be habitat loss caused by man.
Pallid sturgeon evolved for millions of years in a natural river system. These waters had meandering, braided channels and backwaters that provided different depths and flow velocities, which are the essential life requirements of the pallid sturgeon.
Today, the pallid's habitat, the Missouri River, is heavily altered by human modification.
The river has been shortened by hundreds of miles through channelization. Its banks have been lined with dikes and rocky barriers called revetments.
Six major dams punctuate its path. Flows are modified. Flooding is far less common. The seasonal high and low waters are gone. The water coming from the dams is colder than the natural flow, especially in spring. The cold water has limited the production of pallid sturgeon.
The fish has not reproduced successfully for years, the recovery plan said.

In the Same Boat

This endangered species draws attention not only domestically, but also worldwide. The pallid sturgeon is on the International Union for the Conservation of Nature and Natural Resources' Red List of Threatened Species, the world's most comprehensive inventory of the global conservation status of plant and animal species.
The pallid sturgeon is not alone struggling to survive. Among the 20 kinds of sturgeons in the world, five are listed in the endangered category. Its Chinese cousin, the Chinese sturgeon in the Yangtze River, is in the same boat.

Living Fossil Underwater

Looking much like the pallid sturgeon, the Chinese sturgeon also has a "dinosaur-like" appearance with a protruding snout, bony plates and toothless mouth under its jaw with long, fleshy barbells on the side. But it is larger in size and dates back even earlier.
A grownup Chinese sturgeon measures up to 4 meters (about 13 feet) long, and weighs over 450 kilograms (about 1,000 pounds), ranking the third biggest behind the white sturgeon and Atlantic sturgeon. The largest one can weigh 550 kilograms (about 1,200 pounds) and reach 6 meters (about 20 feet).
Because the fish is believed to have evolved 140 million years ago, it is called the "living fossil" by Chinese aquatic biologists, reported China Daily, the only nationally published English newspaper in China.
But the living fossil has even worse living conditions compared with its American cousin.
The deteriorating ecosystem of the Yangtze has accelerated the Chinese sturgeon's slide to extinction, even though the fish has been listed since 1988 as a highly endangered species under state protection.
In the 1970s, scientists observed 2,000 spawning Chinese sturgeons in the Yangtze every year. Now the number is down to several hundred.
Only a thousand of the fish are left in the river, said Wei Qiwei in a National Geographic interview (National Geographic News August 15, 2007). Wei is a lead researcher with the Yangtze River Fisheries Research Institute.

Tribulations of the Chinese Sturgeon

The Yangtze River, at 6300 kilometers (about 3,915 miles), is the longest river in China and the third longest in the world, according to the Ministry of Water Resources of the People's Republic of China.
It flows from its source in Qinghai Province, in west China, eastward into the East China Sea at Shanghai.
The river serves not only as a crucial water source for households and industry, but also as an important shipping route.
As a result, the Chinese sturgeon is threatened by habitat loss and water pollution, just like the pallid sturgeon. In addition, because of the Chinese sturgeon's long migration habit, it faces even greater challenges to give birth to the next generation and continue the species.
Every year Chinese sturgeon swim from the Yangtze, where they are born, to the sea, where they mature. During the mating season, they will swim back to their hatchery habitat in the upper reaches of the Yangtze where they will lay eggs each summer and autumn.
The long swim between the sea and the upper reaches is about 3,000 kilometers (about 1,864 miles), a distance that takes the fish a year to travel. Along the journey they constantly run a gauntlet of nets and ship propellers.
Ninety-six Chinese sturgeons were reported killed by fishing nets or propellers from 1995 to 2001. And by June 2007, 10 injury cases had been reported; only one survived, according to the YRFRI's statistics.
But the greatest threat is not the net or propeller. The huge hydrology projects on the river have taken their toll on the fish's existence.
One hundred and six major bridges, 50,000 dams and numerous water control gates on the main stem and its branches have broken the river into sections and blocked the migration route.
After the Gezhouba Dam was built in 1988, the species was prevented from reaching its breeding habitat in the upper stream above the dam. Instead it now lays eggs in the waters in the middle reaches, near Yichang, Hubei Province. The breeding river length was thus cut down from 800 kilometers (about 497 miles) to 7 kilometers (about 4 miles), and hatchery habitats shrank from 16 to no more than two, Wei Qiwei said.
Since the Three Gorges Project dammed the river in 1997, the environment for the reproduction of Chinese sturgeon has deteriorated even more.
The future extent of the influence of the world's largest hydropower project on the environment and wildlife will be hard to predict before the project is fully completed in 2009. But it is obvious that the Chinese sturgeon will continue to lose its natural habitat, Wei said.
"The Chinese sturgeon is very precious to us," Wei said. "I don't want it to disappear on my watch."

Effort to Save the Sturgeons

What can be done to save this native inhabitant that has managed to survive in the rivers of the world for millions years?
The first step is to prevent the fish from going extinct. That means studying and breeding them in captivity.
Both Chinese and American scientists set trammel nets to capture wild sturgeons from the rivers, just like the scientists of the Missouri Department of Conservation.
Some of the captured fish will be released into the river with electronic trackers attached.
"If we catch a pallid sturgeon, we will insert a chip into the fish's body to tag it," said Vince Travnichek with the MDC.
Jane Ledwin, biologist with USFWS, explained the reasons for tagging the fish. "We tag the fish to track the fish's movements, to measure its survival by location, year and hatchery, and to monitor its growth," she said.
Other captured fish will be propagated artificially.
Scientists of the two countries are trying to breed sturgeons in captivity and put them back into the rivers before the species disappears in the wild.
"The critical issue for us is to make brood stock and then to release the Chinese sturgeon again," said Zeng Lingbing, director of the Fish Pathology Laboratory of the Yangtze River Fisheries Research Institute, as the National Geographical article reported.
Since 1987, the institute has released thousands of sturgeon fry into the Yangtze every year. By 2000, the total number had reached 4.4 million.
On the other side of the earth, American scientists are doing the same job.
The scientists of the USFWS raise larval pallid sturgeon at fish hatcheries and release young fish into the Missouri River when they have grown to 9 inches.
"We are hopeful this is one of many successful efforts as we try to bring this fish back," said Jim Milligan, project leader of the Service's Columbia Fishery Resources Office.
But artificial reproduction and restocking is not the final solution.
"Stocking can only be successful if these fish have the right environment in which to live and grow," said Milligan. "A combination of stocking young fish, restoring habitat and reestablishing more natural river flows is essential to a comeback of the pallid sturgeon."
Chinese scientists speak with the same voice on this point.
"Habitat restoration is the crucial way to save the species," Wei Qiwei said. "But it is far more difficult."

Why Save the Endangered Species?

Both Chinese and American scientists have spent about 20 years to study and recover the sturgeons, and they still have a long way to go.
To some people the sturgeons may be not attractive creatures, so why should human beings invest tremendous money and effort to save them?
The USFWS gives this explanation on its website:
"Species interact in complex ways, and survival of all native species in a given region is an indicator of a healthy ecosystem. If one species declines, others can become negatively affected."
Like a canary in a coal mine, the plight of the pallid sturgeon and the Chinese sturgeon serves warning that the overall health of the environment has suffered.
Saving endangered species is not only for wildlife, but for ourselves, Jane Ledwin said.
She quoted Congressman John Dingell to illustrate her point:
"Living wild species are like a library of books still unread. Our heedless destruction of them is akin to burning that library without even having read its books… Preventing the extinction of our fellow creatures is neither frivolity nor foolish environmental excess; it is the means by which we keep intact the great storehouse of natural treasures that make the progress of medicine, agriculture, science and human life itself possible."