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July 15, 2008

Survey probes Toccoa for rare fish, tests study methods

Submitted by the Georgia Department of Natural Resources



SOCIAL CIRCLE — A unique survey on the Toccoa River this summer is searching out the river’s rare fish, testing new sampling protocols and possibly helping chart a conservation course for this clear-water gem of northeast Georgia.

Using snorkels, kayaks and backpack electrofishing units, a team of Georgia Wildlife Resources Division biologists and staff is exploring the Toccoa’s nearly 40 miles. The river tumbles north from Suches to the Tennessee state line, where the flow is renamed the Ocoee, best known as turbulent host of the 1996 Olympic whitewater events.

To wildlife biologists like Brett Albanese, a senior aquatic zoologist with Wildlife Resources, the Toccoa’s calling card is state-protected fishes. For example, the watershed is home to Georgia’s only known populations of wounded, olive and tangerine darters. These small perches are sensitive to habitat changes and hard to sample, particularly in wide, deep and swift streams like the Toccoa.

But Albanese hopes the survey he is leading can reliably estimate the proportion of mainstem Toccoa sites occupied by the darters and the state-endangered blotched chub.

As he explains, several samples taken from each site allow researchers to estimate the detection probability, or chance of observing or catching a species when it is present. That factor is then used to adjust the overall estimate of the percentage of sites occupied, thus accounting for a significant bias associated with surveys for rare species. The information can then become a baseline for gauging changes in fish populations over time.

In addition, Albanese hopes the survey’s primary sampling method - spotting fish, not shocking them up - can be useful for monitoring other imperiled fishes in the Southeast with minimal harm. A small percentage of sites are electrofished so results of the methods can be compared.

Albanese has another goal, as well: to inform residents about the aquatic diversity at risk from development along the Toccoa. The river is drawing a surge of new homes. Lake Blue Ridge long ago altered the waterway, with dam releases that turn the downstream Toccoa into a tailrace river.

Researchers are measuring the river canopy’s cover and noting changes in the riparian zone, which is where land and water meet. Albanese said they’re spreading the word even as they work.

“We’re encouraging people to restore the riparian habitat, and also not disturb riparian zone vegetation when new homes and cottages are built.”

Albanese, staffer Deb Weiler and interns Katie Owers and Will Pruitt will be on the river through early August. Sample sites are randomly picked, floated in kayaks, searched by snorkel and sometimes sampled with an electric probe that temporarily stuns the fish.

Habitat data are collected as the snorkelers try to warm up from the Toccoa’s cold waters, Albanese said.

The pace sometimes belies the Toccoa’s gentle image. But the results could help preserve it.

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