Richarde M. Talbot(email@example.com)
AU FISHERIES STUDY SHOW NEGATIVE IMPACT OF HARRIS DAM
AUBURN - A Sept. 16 study to determine the impact on fish populations in the Tallapoosa River around Horseshoe Bend since construction of Harris Dam has shown a significant decline in catfish and minnow populations.
Elise Irwin, assistant leader of fisheries for the Alabama Cooperative Fish and Wildlife Research Unit at Auburn University, said the results are more dramatic than anticipated. Her findings bolster the claims of local residents who say fishing has d eclined in the years following construction of Harris Dam in the early 1980s.
The study, which was done cooperatively between Alabama Power Co., AU and various state agencies, is a replication of one done in 1951 by AU fisheries researcher H.S. Swingle in roughly the same area along the Tallapoosa River, Irwin said
"What we found were reversals in the fish community, which was a catfish minnow dominated community where minnows comprised 47 percent and catfish comprised 44 percent," said Irwin. "When we did this study, the community has now shifted to one dominated by black bass, sunfish and crappies."
The new study shows a drop in numbers as well as mass in the fish population. In 1951, there were 798 one- and two-inch channel catfish collected and 1,104 minnows collected. In September, researchers retrieved 54 one- and two-inch channel catfish an d 41 minnows. In the 1951 sampling biomass from the river was 45 pounds per acre, but in 1996 it has dropped to 29.3 pounds per acre.
"That sounds like it's not such a bad trade-off, but my feeling is the black bass there are not doing that well," said Irwin. "And the more specialized fish, like catfish and minnows, are getting hammered."
Black bass, sunfish and crappie -- fish Irwin refers to as generalist populations because they can exist on whatever habitat is available -- now comprise 73 percent of the fish community instead of 5 percent; and black bass account for 14.5 percent o f that figure. Referring to a fistful of pictures taken in a 1951 fishing trip, Irwin points out the large size of the two dozen bass caught. Bass sampled in September were not half the size of those pictured. Researchers plan to study the fishes' ear bon es, or otolists, to determine the age of the fish. This data will then be compared against the size and weight data collected at the site to determine if Irwin's hypothesis is correct and the fish are indeed stunted in growth.
"As I understand it, just about every parameter you can measure fish populations by has shown a decrease by half, or more than half, since Harris Dam was built," said Jon Hornsby, environmental coordinator for the Alabama Department of Conservation a
nd Natural Resources. "We're going to study the data and evaluate the need for additional flow. We need a minimum flow."
Currently, water flow is erratic because it is determined by fluctuations in the demand for power. The flow can go from zero cubic feet per second to 16,000 feet per second and back to zero cfs in a day's time. Irwin and Hornsby cite Thurlow Dam as a similar situation that seems to have been resolved with an established minimum flow. Researchers plan to share the results of the study with Alabama Power officials.
"Below Thurlow Dam, a minimum flow of 27 percent of the average annual flow was established, and that's the highest we've ever been able to get. That seems to be working. If we could be convinced by a scientific study that a 20 percent flow can prote ct the fisheries, we'd accept it," Hornsby said. "We'd like to get more than 30 percent of annual average flow, but we've never been able to get that."
Irwin noted other problems in the river's ecosystem since the dam was built. Grasses lining the riverbank in the 1951 photographs are no longer present.
"There are no grasses, which is important for habitat for juveniles and from a productivity standpoint. The plants are really at the bottom of the food web, they provide food for invertebrates, which are eaten by the fish, and they provide shelter,"
"If we can get some modifications of flow, the river will be incredible for a float trip (where you put in the bait and float down the river in a canoe). Now, if you put in at Malone's and try to go to Wadley you have to drag your boat about six mile s," she said.
CONTACT: Irwin, 844-9190 (firstname.lastname@example.org); Hornsby, 242-3851