|For Immediate Release
August 19, 1998
Contact: Tom MacKenzie
For 122 years the fish was believed to be extinct. Then in 1991, biologists from
the Georgia Department of Natural Resources discovered some robust redhorse in the Oconee
River near Toomsboro,Georgia.Scientists estimated that this population remnant, surviving
along a 70-mile stretch of river,numbered as few as 2,000. Today, some 7 years later, more
than 27,900 artificially-reared fish have been
introduced into Georgia Atlantic slope rivers.
|As its name implies, the robust redhorse is a sizable fish, that when fully-grown measures up to 30 inches in length and weighs as much as 17 pounds. It was first described in 1870 by a renowned naturalist of the time, Edward Drinker Cope. The fish is believed to have once existed in large numbers in the then-pristine rivers of Georgia and the Carolinas. Remains of the species found at archeological sites in the Southeast clearly indicate that it was once an important food source for Native Americans and perhaps early settlers as well.|
After its rediscovery seven years ago, biologists studied the Oconee River population between Milledgeville and Dublin, Georgia, and found it to consist almost entirely of older adults. The fish, which has a longer life span than most freshwater species, can live for as long as 26 years. The advanced average age of these survivors, however, raised an immediate red flag to fisheries experts, because it clearly indicated that the fish's reproductive rates were poor.
Once it became evident that the future of the new-found robust redhorse was nothing short of perilous, the Robust Redhorse Conservation Committee was established in 1995. Signatories to the Memorandum of Understanding, a document outlining the mission of the Committee, are the Georgia Department of Natural Resources, the U.S. Fish and Wildlife Service, the South Carolina Department of Natural Resources, the North Carolina Wildlife Resources Commission, the U.S. Geological Survey-Biological Resources Division, U.S. Forest Service, U.S. Army Corps of Engineers, Georgia Power Company, Carolina Power and Light, Duke Power, the University of Georgia and the Georgia Wildlife Federation. The mission of the Committee is to analyze factors leading to the decline of the fish, to attempt to re-establish the species to a sustainable level within its former range and to take actions that will recover the species to the point that it will not have to be placed on the federal list of endangered and threatened species. The overall coordination of the recovery effort is under the general direction of the Georgia DNR.
To aid in its recovery, fisheries biologists in the Spring of 1992, began collecting brood fish from the river and transporting them to the Service's Warm Springs National Fish Hatchery in Warm Springs, Georgia. Later, a decision was made to transport fertilized eggs from the Oconee River to the Warm Springs hatchery rather than shipping the brood fish. The process of collecting fertilized eggs was no mean feat. It involved the research team developing just the right hormone treatment to induce the females to ovulate and release ripe eggs while obtaining sperm from the male fish to fertilize them. Although initial efforts were unsuccessful, later studies conducted in cooperation with the University of Georgia and funded by Georgia Power Company have led to the production, to date, of 409,000 fry.
According to the Service's Southeast Regional Director, Sam Hamilton, another challenge facing biologists was to find the exact conditions necessary to allow the embryos to develop into fingerlings -- young fish approximately 3-5 inches long. Over a two-year period, beginning in March 1995, some 25,000 fry , stocked in state hatcheries in Georgia and South Carolina. Here they thrived and were eventually released as 8-10-inch fingerlings into Georgia's Broad River -- a tributary of the Savannah River. Approximately 1,500 others were introduced into the nearby Ogeechee River. An additional number were retained in ponds at the Warm Springs National Fish Hatchery to produce larger juveniles and adults for further study and intensive culture testing while some 4,500 other fish are being held at the Piedmont National Wildlife Refuge near Round Oak, Georgia, to serve as a backup robust redhorse community just in case some catastrophic event decimates the surviving Oconee River population.
Hamilton said he is heartened by the recent outstanding fingerling survival rates in hatchery ponds and noted that these rates are the highest achieved in the 6 years that the recovery effort has been in place. "This success represents a significant advance in recovery efforts for the species," he said. He noted, however, that the fish's ultimate fate rests upon much larger issues.
The major causes of the decline and extinction of fish and mussel species in the Southeastern United States, Hamilton said, are the sedimentation of rivers and streams, the damming of waterways that isolate populations and block migration channels, and the introduction of exotic species that prey on native species or, like the zebra mussel, inundate their habitats.
During the past 100 years, human settlement in the Southeast has resulted in extensive erosion and sedimentation of rivers and streams caused by deforestation, commercial development and row crop agricultural practices. The damming of waterways and the extensive muddying of once-clear and pristine waters may also have seriously harmed species like the robust redhorse, that migrates to shallow river areas, covered with clean gravel spawning sites to protect eggs and developing larvae.
The fertilized eggs incubate and hatch in the small spaces between the tiny pieces of gravel. The newly-hatched larvae are unable to swim and in the 8-11 days it takes for their delicate yolk sacks to be absorbed, they need the shelter offered by the gravel. They cannot survive if smothered by layers of silt.
Since the late 1800s, dams have been built on almost all rivers within the historic range of the robust redhorse. These dams have blocked migration channels and impoundments have inundated spawning areas. An additional threat to this fish was the introduction, in the 1960s and 1970s, of the flathead catfish.. This voracious predator is considered responsible for the decline of a number of native fish species.
In spite of the Committee's successes, to date, to recover the robust redhorse, Hamilton says the Service and its partners will still have to play a waiting game. "Only time will tell if the fish, once recovered, can continue to maintain a sustainable population level," he said.
|River-bound fingerlings are fitted with tags that enable scientists to
follow a fish's progress. "The robust redhorse reaches sexual maturity in about
7 years and it's going to take us at least that long to really tell if the reintroduction
works," Hamilton said.
The U.S. Fish and Wildlife Service is the principal Federal agency responsible for conserving, protecting, and enhancing fish and wildlife and their habitats for the continuing benefit of the American people. The Service's nearly 93 million acres include 514 national wildlife refuges, 78 ecological services field stations, 66 national fish hatcheries, 50 wildlife coordination areas, and 38 wetland management districts with waterfowl production areas.
The agency enforces Federal wildlife laws, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, administers the Endangered Species Act, and helps foreign governments with their conservation efforts. It also oversees the Federal Aid program that distributes Federal excise taxes on fishing and hunting equipment to state wildlife agencies. This program is a cornerstone of the Nation's wildlife management efforts, funding fish and wildlife restoration, boating access, hunter education, shooting ranges, and related projects across America.
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Release #: R98-076
1998 News Releases
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