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Upstream Battle to Save “The Desperate Dozen”

Scientists Seek Ways to Spare Twelve Fish Species from Extinction

Pygmy Scupin

Chattanooga, Tenn. (November 10th, 2008) – If letter grades were assigned for freshwater biodiversity, the southeastern United States would receive “straight A’s” every year. There are more than 675 species of fish living here, which is more than half of the total number of species found in the rest of the nation. Unfortunately, one-quarter of the region’s fish species are now considered imperiled.

“This major conservation crisis calls for immediate action to conserve and protect the remaining populations and their habitats,” says Dr. Anna George, the Tennessee Aquarium’s chief research scientist.

Dr. George and more than 200 other fish scientists from Missouri to Florida make up the Southeastern Fishes Council (SFC). With support from the World Wildlife Fund, these aquatic biologists have identified twelve southeastern fish species that are disappearing the most rapidly from their home ranges. Some species like the Alabama sturgeon could vanish forever within a few years. “We decided to focus our efforts on those 12 species most likely to become extinct, the Desperate Dozen, in order to reverse their precipitous decline and put them on the path to recovery,” Dr. George said.  So this past summer, these experts selected the Desperate Dozen based on the size of their range, abundance, and severity of threats.  These results will be presented at the SFC meeting November 13th-14th in Chattanooga so that scientists and resource managers can discuss how best to preserve them.  Though most of these species are small in size and range, their role in the region is large.  “Our native fishes are part of our natural heritage in the Southeast,” says Dr. Bernard Kuhajda, researcher at The University of Alabama and Chair of the SFC.  “We have to conserve that heritage so that our kids and grandkids can enjoy the same quality of life - and fishes -that we have now.”

Half of the Desperate Dozen are from a group known as darters, named because they lack a swim bladder and dart across the bottoms of streams.  These brightly colored fishes have been nicknamed the “Warblers of the Water,” not only for their appearance, but also their distinctive behaviors.  The Conasauga logperch, the closest of the Desperate Dozen to Chattanooga, feeds by flipping rocks on stream bottoms and eating the bugs found underneath.  Another imperiled darter displays reversed parental roles. “Male relict darters are in charge of the eggs.  They protect nests on the underside of flat rocks.  Females actually look for the presence of eggs in these nests to ensure their potential mate is a good choice for guarding their offspring,” says Dr. Kuhajda.

However, these remarkable characteristics mean these darters can be extremely sensitive to habitat changes in our waters.  When stream banks erode, the resulting sedimentation impacts habitat quality.  When rocks become embedded in sediment, logperch are not able to flip them.  Relict darters lose nest sites when sediment fills the space between rocks and the stream bed.  Other species, such as the vermilion darters, may have difficulty finding their brightly colored counterparts in the cloudy water.

It isn’t only fishes with small ranges that suffer from the effects of habitat change; fishes that were once found in hundreds of miles of big rivers are now hovering on the brink of extinction.  Only two individuals of the Alabama sturgeon, a fish that once roamed more than 1,000 river miles of the Mobile Basin in Alabama and Mississippi, have been captured in survey efforts over the last nine years.  “Habitat changes can have impacts upstream and downstream,” says Dr. Kuhajda, “which is why it’s so important to have this discussion on a regional scale.”

Because these fishes are so imperiled, you won’t be able to find any on display at the Tennessee Aquarium in downtown Chattanooga, but you can find fish that are closely related to them.  If you look closely at the Darter Tank in the Tennessee River Gallery, you can find two other species of logperch that also feed by flipping rocks.  Look for sturgeon and pygmy sunfish on display in the Aquarium’s River Journey building as well.  However, just seeing close relatives of these species isn’t enough.  These Desperate Dozen fish represent a unique part of our freshwater ecosystems.  “They are the canary in the coal mine,” said Dr. George.  “And that canary is currently very, very sick.”

Vermillion Darter

The Desperate Dozen:

  1. Alabama cavefish (Speoplatyrhinus poulsoni)
  2. Alabama sturgeon (Scaphirhynchus suttkusi)
  3. Bayou darter (Etheostoma rubrum)
  4. Chucky madtom (Noturus crypticus)
  5. Conasauga logperch (Percina jenkinsi)
  6. Diamond darter (Crystallaria cincotta)
  7. Pearl darter (Percina aurora)
  8. Pygmy sculpin (Cottus paulus)
  9. Relict darter (Etheostoma chienense)
  10. Slender chub (Erimystax cahni)
  11. Spring pygmy sunfish (Elassoma alabamae)
  12. Vermilion darter (Etheostoma chermocki)

Ways you can help protect the Desperate Dozen and other aquatic species

  • Conserve water – Helps ensure adequate stream flow.
  • Conserve electricity – Reduces demand for environmentally harmful power.
  • Recycle paper – Saves forested land reducing erosion and silting of streams.
  • Recycle used motor oil – Keeps streams and groundwater from becoming contaminated.
  • Clean your streams – Organize or participate in a local stream clean-up.

Fish experts gather in Chattanooga to save aquatic species
At a conference hosted by the Tennessee Aquarium, the Southeastern Fishes Council will focus efforts on twelve southeastern fish species most likely to become extinct. Click here (pdf 11 MB) to read the full scientific report about “The Desperate Dozen”.


The Tennessee Aquarium inspires wonder and appreciation for the natural world. Admission is $19.95 per adult and $12.95 per child, ages 3-12. Each ticket purchased helps support Aquarium conservation programs. The IMAX® 3D Theater is next door to the Aquarium. Ticket prices are $8.50 per adult and $6.00 per child. Aquarium/IMAX combo tickets are $25.95 for adults and $17.95 for children. Excursions aboard the new River Gorge Explorer depart daily into “Tennessee’s Grand Canyon.” Advance tickets may be purchased online at or by phone at 1-800-262-0695. The Aquarium, located on the banks of the Tennessee River in Chattanooga, is a non-profit organization. Open every day except Thanksgiving and Christmas, the Aquarium and IMAX are accessible to people with disabilities.

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