NASHVILLE, Tn (TWRA) - On New Year's Eve 2008, Jack Paul Watson landed a 5 lb., 14 oz. spotted bass on Parksville Lake. The Tennessee Wildlife Resources Agency (TWRA) later confirmed that this spotted bass was the largest one ever landed in Tennessee, but that is not the end of this story.
"Until a few years ago, there were very few, if any, spotted bass in Parksville Lake" said Mike Jolley, a fisheries biologist with TWRA. "If a fisherman caught a black bass from this lake, it was usually either a largemouth or a smallmouth. Then in 2005, a few spotted bass from the lake started showing up in our annual electrofishing survey."
Since then, TWRA has been finding more and more spotted bass in ParksvilleLake. This spring, 69 percent of the black bass sampled by TWRA from Parksville were spotted bass. The only likely explanation for this "invasion" was that someone released a few spotted bass in the lake and they were able to establish a growing population.
More interesting to biologists and anglers was the fact that the spotted bass in ParksvilleLake seemed to be reaching larger sizes than most other spotted bass in Tennessee. When Watson's fish was caught, TWRA decided to investigate further.
After sending samples from Watson's fish to a geneticist, TWRA learned than this fish was from a different strain than Tennessee's native spotted bass. Further analyses revealed that the spotted bass was likely from a strain in northern Alabama that is known to reach larger sizes. The TWRA suspects that someone transported spotted bass from Alabama and then released them in Parksville Lake. "Not only was this act illegal, it could have severe ecological consequences" said George Scholten, TWRA's Reservoir Program Coordinator. "Anytime a new species is introduced it has the potential to change the way the entire ecosystem operates. These changes might seem slight at first but over the long term they can result in serious problems."
In the Parksville Lake situation, one concern that biologists have is that this exotic strain of spotted bass could out compete and replace the largemouth and smallmouth bass in that reservoir. Another concern is hybridization. The Alabama spotted bass strain is known to hybridize with smallmouth bass and have negative effects on both populations. Although anglers are catching larger spotted bass now, it could be at the expense of their future largemouth and smallmouth fishing.
"To make matters worse, we recently received a report of blueback herring in Parksville Lake" said Jolley. Blueback herring, another exotic species that looks very similar to an alewife, are known to upset fish communities and have caused problems in several sport fisheries in Georgia and North Carolina. Since blueback herring look very similar to many native shad species, Tennessee anglers should avoid catching bait from Parksville Lake and other waters where blueback herring are known to exist.