A perfect day for paddlefish

David Hoke, a biologist with the Tishomingo National Fish Hatchery, prepares to toss back a paddlefish after reading its unique jaw tag, which will help track the growth and longevity of the fish

By Environmental News Network staff

They appear like they came right out of Jurassic Park, primitive and odd-looking. You could call them swimming dinosaurs. Fossil records of paddlefish don't differ much from those alive today.

After a long hiatus, these big-river behemoths now swim the waters above Denison Dam in Lake Texoma on the Oklahoma-Texas line.

The dam blocked spawning migrations and the populations above the dam disappeared. But thanks to a joint effort between the U.S. Fish & Wildlife Service and the Oklahoma Department of Wildlife Conservation, paddlefish may soon be seen migrating up to Wichita Falls on the Red River and to Davis, Oklahoma, on the Washita River.

"These fish are fast growers," said Kerry Graves, manager of the Service's Tishomingo National Fish Hatchery in Tishomingo, Oklahoma. "I wouldn't be at all surprised to see these stockers reach 50 pounds in a few years. If other paddlefish stockings in Oklahoma are any measure, these fish will get big in a hurry."

Big fish will spawn, too, and that's the whole idea: to get self-sustaining paddlefish populations back to where they once lived.

Durant State Fish Hatchery and the service's Uvalde National Fish Hatchery in Uvalde, Texas, joined with the Tishomingo facility recently stocked 21,000, 12-inch fish at Briar Creek Landing. And there's more to come. This fall, Inks Dam National Fish Hatchery in Burnet, Texas, plans to plant another 10,000 fish.

When adult fish start making the spawning runs and young fish survive, that will be the true mark of success. Another mark will be fishermen wrangling ashore huge, 75-pound fish.

Paddlefish are named for their paddle-like snout used to locate food such as tiny microscopic plankton.

Farther west, another conservation effort continues. Fish biologists from the U.S. Fish and Wildlife Service and several other federal and state resource management agencies gather every year on the lower Colorado River for an event affectionately known as the "razorback roundup."

The roundup coincides with the spawning of the razorback sucker, an endangered fish.

"If other paddlefish stockings in Oklahoma are any measure, these fish will get big in a hurry," said Kerry Graves, manager of the service's Tishomingo National Fish Hatchery in Tishomingo, Oklahoma

With the aid of electrofishing gear and trammel nets, biologists collect sexually mature fish and haul them to Willow Beach National Fish Hatchery, Arizona, where they are spawned. Later, the adults are returned alive to the waters where they were collected.

Why it has to be done speaks to the problem of habitat loss and competition with non-native species.

"Razorback sucker populations took a heavy hit from habitat loss and the introduction of non-native fishes,"; said Manuel Ulibarri, manager of Willow Beach National Fish Hatchery. "Dams altered water temperature and inundated habitats necessary for survival. Those razorbacks that do spawn in the wild are disadvantaged by carp and other non-native fishes that eat the eggs. The net result is a severely depleted native stock of mostly very old fish."

The oldest fish in the wild now were probably hatched during the Eisenhower administration. These fish live as long as 45 years, but presently without successful natural reproduction. Old fish make up most of the population, and the population gets smaller and smaller.

"Fully 90 percent of the world's razorback sucker population occurs in Lake Mojave," said Chuck Minckley of the service's Arizona Fishery Resources Office. "That translates to a small number of fish in a small area. Our annual roundup helps us manage for a wild population that is increasingly becoming older."

In Lake Mojave this spring, biologists collected 80 razorback sucker between Willow Beach National Fish Hatchery and Hoover Dam. Those fish yielded 300,000 larvae that will be stocked throughout the Colorado River system when they are larger. Leading-edge captive breeding techniques, such as sperm cryopreservation and egg storage, ensure a diversity of genetic material for future generations of razorbacks.

Most of the young razorbacks are grown in predator-free waters for about 18 months when they reach about 10 inches. At that time biologists tag and release them to face the rigors of the wild.

Downstream in Lake Havasu, 38 adult razorbacks were collected, all but one of which were tagged. That's a clear indication that repatriated razorbacks are surviving. Minckley estimates that about 9,000 adult fish remain in the wild at the two lakes with an additional 3,000 to 4,000 repatriates.

The annual roundup is a management tool that fish biologists use to conserve this species. Data collected during the roundup helps biologists determine the distribution and population abundance of this imperiled fish.

"What we do is fundamentally no different than propagating California condor," said Minckley. "When things get too rough in the wild because of man's actions, man has the responsibility to step in and take corrective actions. If we didn't razorbacks would go extinct."

The razorback sucker is named for its keel-like ridge on its back that helps it navigate fast-flowing water.

Copyright 2000, Environmental News Network, All Rights Reserved

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U.S. Fish & Wildlife Service
Oklahoma Department of Wildlife Conservation
Tishomingo National Fish Hatchery
Uvalde National Fish Hatchery
Inks Dam National Fish Hatchery
Willow Beach National Fish Hatchery
Arizona Fishery Resources Office Hoover Dam
paddlefish
razorback sucker
more information on the razorback sucker

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