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DNA mapping begins a long road to recovery for endangered Tennessee fish

Cumberland Darter (Etheostoma susanae) (credit: Bernie Kuhajda)

(Editor's note: This story was contributed to NewsChannel 9 by the Tennessee Aquarium's Casey Phillips).

Thanks to a host of largely human-induced threats, it’s all too easy for an animal to be pushed close enough to the brink to warrant protection under the Endangered Species Act.

But improving an endangered animal’s prospects to the point that it can come off the list? That’s a much harder proposition.

On April 2, the U.S. Fish and Wildlife Service published a draft recovery plan for the Cumberland Darter, a pencil-shaped, three-inch fish whose range has been reduced to just a handful of streams in Southeast Kentucky and Northeast Tennessee.

The Cumberland Darter’s precipitous decline was caused by poor water quality, man-made alterations to waterways and habitat degradation caused by runoff-born sedimentation and chemicals entering its native streams. On Aug. 9, 2011, the Cumberland Darter was federally listed under the Endangered Species Act.

U.S. Fish and Wildlife’s nine-page plan, which will be available for public review until June 26, lays out an extensive strategy for evaluating the health of (and strengthening) existing populations of Cumberland Darters and re-establishing the species throughout its historic range.

If the plan is successful, the Cumberland Darter could join the American Alligator, Gray Wolf and Grizzly Bear among formerly endangered animals that were saved by the concerted, collaborative efforts of conservationists, scientists, policymakers and private land owners.

“The Cumberland Darter was pushed to the edge, and it happened to a fish that is already restricted to a small range,” says Tennessee Aquarium Science Programs Manager Dr. Bernie Kuhajda. “The human effects are magnified by this being a fish that is not widespread.”

U.S. Fish and Wildlife’s plan calls for scientists to fill in information gaps regarding the genetics of wild Cumberland Darters. This will help establish which populations are diverse and which ones are more genetically similar. Last year, U.S. Fish and Wildlife approved a grant to fund a population and genetic survey of the Cumberland Darter by the Tennessee Aquarium Conservation Institute.

“They just completed the recovery plan, and population genetics is a high-priority item, so we’re ahead of the game in being proactive and knocking out one of the top objectives,” says Dr. Matthew Thomas, an ichthyologist and program coordinator with Kentucky Department of Fish and Wildlife Resources, which is partnering in the recovery effort.

“By knowing the genetic diversity of those populations, we will have a better idea how viable they are,” Thomas adds. “Given that the Cumberland Darter has such a limited range, that’s a concern. The work that Dr. Kuhajda and the Tennessee Aquarium are doing will hopefully shed some light on that, and we can move forward with more informed conservation actions.”

Scientists from the conservation institute have taken fin clippings from wild Cumberland Darters and tested them in the genetics lab at the conservation institute’s new freshwater science center in Chattanooga. The results of these tests will help ensure fish with lower genetic diversity — and thus lower potential resilience to environmental change — are not introduced into healthy, genetically diverse populations.

“If you don’t know how genetically distinct these populations are, you may do more harm than good with a propagation and stocking program,” Kuhajda says.

At least one point in the Cumberland Darter’s favor is that most of the remaining populations are found in streams flowing through Kentucky’s Daniel Boone National Forest. Those lands are federally managed by the U.S. Forest Service, one of U.S. Fish and Wildlife’s conservation partners.

A few populations, however, are found in stretches of waterway flowing through private lands. By drafting a clear roadmap for restoring the Cumberland Darter, U.S. Fish and Wildlife and its partners will hopefully find it easier to secure the vital cooperation of policymakers and landowners, Kuhajda says.

U.S. Fish and Wildlife’s plan estimates the cost of recovery efforts at $35.8 million, with a projected recovery/delisting date of 2047. That cost may seem high, Kuhajda says, but the Southeast’s healthy, diverse aquatic ecosystems — of which the Cumberland Darter is a part — provide valuable benefits to humans, including hobby and sport fishing, clean drinking water and beloved recreation areas.

“And morally, it’s the right thing to do to try and keep all these different, cool aquatic organisms around us from going extinct,” Kuhajda says. “Since it’s humans that are causing them to come to the brink, the least we can do is to keep them from disappearing forever from our planet.”

The draft of the U.S. Fish and Wildlife recovery plan for the Cumberland Darter can be viewed online here.

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