SOCIAL CIRCLE, Ga. (1/27/2010)
The Etowah and Conasauga rivers are known for rare fish and biological diversity. Recent research reveals that the river between them – the Coosawattee – is in the same league.
Last summer, staff from the Georgia Wildlife Resources Division’s Nongame and Fisheries sections sampled the north Georgia river from Ellijay to Carter’s Lake and the stream’s two largest headwater tributaries, the Cartecay and Ellijay rivers. Results included new records for federally threatened goldline darters – documented in Georgia only in the Coosawattee – and field data critical to fleshing out a GIS-based analysis of the watershed.
The work labeled the Coosawattee as one of Georgia’s top three rivers for imperiled fishes, part of a Southeastern Fisheries Council assessment aimed at helping prioritize U.S. waterways for conservation. Each participating state relied on a recently published list of imperiled fishes recognized by the American Fisheries Society’s endangered species committee. Statewide analysis ranked the Coosawattee third with nine of the listed fishes (including two species last seen in the 1960s). The Etowah led with 14 imperiled fishes. The Conasauga followed with 12.
All three rivers are in the Coosa River basin. The Coosawattee rates data-poor, however, compared to studies of rare species and common threats on its neighbors. The project “allowed us to look a lot more closely at the Coosawattee,” said leader Brett Albanese, a senior aquatic zoologist with the Nongame Conservation Section.
Crunching details ranging from aerial snapshots to land-cover statistics marked expected threats such as riverside deforestation for vacation homes and farm runoff. Yet there were also surprises, like the 660 dams in the watershed. Dams block free-flowing stream habitat and fish movement.
GIS specialist Thom Litts of Wildlife Resources’ Fisheries Section used GIS and Maxent species habitat modeling software to develop a computer model that identifies stream sections in which threatened and endangered fishes might be found. “We’re thinking of this as a probability of suitable habitat,” Litts said.
Next comes fieldwork to vet the modeling, plus additional analysis to determine conservation remedies. Albanese lists protecting important populations of goldline darters and state-endangered holiday, trispot and bridled darters as priority.
There is a silver lining. Sampling showed that goldline darters are “doing pretty well” in the Coosawattee, Albanese said.
The challenge: Making sure this river receives the conservation attention its rank commands.
WHY THESE THREE RIVERS?
** Researchers identified the number of imperiled fish taxa, or species, in each of Georgia’s 52 catalog-level hydrologic units. (Often factored into GIS analyses, hydrologic units and associated codes, or HUCs, are part of a U.S. Geological Survey watershed classification system used to identify and “nest” drainage areas in the U.S.)
** The Etowah had 14 imperiled taxa, the Conasauga had 12, and the Coosawattee, nine (two known only from historic records).
** Of Georgia’s 265 native fish taxa, 62 (23 percent) are imperiled. Five are considered extirpated or extinct within Georgia. The last documented records of these extirpated species date to between 1877 and 1953.