The Georgia Department of Natural Resources has found a second invasive species of catfish in the Satilla River.
Fisheries biologist Tim Bonvechio said a blue catfish was removed from the Satilla on May 25 by a crew working to rid the river of flathead catfish.
"This is the first blue on the Satilla," Bonvechio said, "and our current stance is to remove them along with the flatheads."
Bonvechio heads a Waycross-based operation that has been taking flatheads out of the river for five years.
Flatheads are prized by fisherman because of their immense size. Growing to more than 100 pounds, they were illegally introduced by fishermen in the mid-1990s into the blackwater stream that meanders 100 miles from near Douglas to the coast.
The voracious feeders devastated the redbreast sunfish population, a native species prized by anglers, prompting the DNR to begin its eradication effort.
The flathead population has been greatly diminished, Bonvechio said, but now comes this new threat.
"The blue cat is not really the beast the flathead is, but this is not at all a good thing for the Satilla," Bonvechio said. While not as voracious as flatheads, blues nonetheless could have a harmful impact on native mussel and fish species, he said.
The blue catfish is native to just one river in Georgia, the Coosa in the northwest corner of the state, but has spread south and proliferates in the Altamaha River system, Bonvechio said.
He speculates that it reached the Satilla by swimming through saltwater streams from the Altamaha just north of Brunswick to the Satilla just to the south.
"The blue catfish has a high tolerance for saltwater," he said. "It may have come around through the Intracoastal Waterway."
Flatheads are opportunistic eaters, Bonvechio said, and have harmed other fish populations, including bullhead catfish. A young Atlantic sturgeon, too, was removed from the stomach of a flathead last year, indicating that flatheads in the Satilla may pose a threat to that protected species, Bonvechio said.
It's another reason to keep up the eradication effort, he said.
Bonvechio and his crews use electro-fishing equipment to stun the fish and cause them to rise to the surface. The undesirable fish are scooped up and the rest left alone.
High levels of mercury in the fish make them unfit for consumption. Most wind up in a landfill, but a few go the Okefenokee Swamp Park to feed its alligator population.
The crews have removed 20,565 fish weighing 55,174 pounds from the river since 2007, Bonvechio said.
The first year, the fish averaged 5.8 pounds, he said, but are now down to less than 2 pounds, meaning a sizable dent has been put in the breeding stock.
"We've been able to fish down the population tremendously," he said.
Satilla Riverkeeper Bill Miller said the flathead project has been successful in restoring the redbreast population.
"Flathead catfish may be a trophy fish to some, but they're not beneficial to our watershed," he said. "For us who grew up on the Satilla, the redbreast is our trophy fish."