High in the mountain streams in southeast Tennessee, the survival of a tiny fish called the Laurel Dace hangs in the balance. The Laurel Dace (Chrosomus saylori) is the size of a minnow, and it is only known to ever exist in eight streams along the Cumberland Plateau.
Recent drought conditions have all but dried up its habitat initiating an emergency effort by fisheries biologists to save the few that are left.
Before the 2024 drought the Laurel Dace was already one of the most federally endangered aquatic species in the U.S. With its limited habitat in a few mountain creeks near Chattanooga the region’s 13-inch rain deficit for the year left the already vulnerable fish with a limited chance for survival. The drought conditions decimated the flowing streams into puddles of stagnant water separated by stretches of torrid cracked mud.
Fisheries biologists from the Tennessee Aquarium and other conservation stakeholders are now in a race against time to collect and temporarily house as many of the surviving Laurel Dace as possible. While the long-term outlook for the limited populations left of Laurel Dace is uncertain, those walking the creeks to save them are relentless in their commitment to making sure the end-result is not extinction.
The colorful Laurel Dace faces extinction without current rescue efforts to save it. (Photo: Tennessee Aquarium)
Cascading Impacts
Reaching a maximum size of only about three inches, the Laurel Dace is one of the most colorful aquatic species in Tennessee waters. Males develop bright red bellies with a red stripe and yellow fins during spawning season and they make their home in the pristine streams flowing throughout the Tennessee mountains.
“They were named Laurel Dace because the streams they live in are surrounded by mountain laurel, which is an absolutely beautiful flower,” said Dr. Anna George, Vice President of Conservation Science and Education at the Tennessee Aquarium. “There are also hemlocks that line the creeks. Historically, they have been very rocky streams.”
The Laurel Dace was discovered along the Cumberland Plateau in 1976 but wasn’t a recognized species by scientists until 2001. By then, given its limited distribution, the Laurel Dace was already facing threats to its existence. By 2011 the Laurel Dace was placed on the U.S. Fish and Wildlife Service list of endangered species making it one of the most critically endangered aquatic species in North America.
“That basically says that from the moment they were recognized by science, the wheel started turning because unfortunately for something with such a restricted range as the Laurel Dace, things don't even have to be that bad before they become endangered,” Dr. George said.
Since its discovery, the Laurel Dace has faced an uphill battle for its existence.
Throughout the last 30 years pollutants and sediments caused by topsoil runoff as forests became agricultural land have negatively impacted the Laurel Dace habitat. Instead of the rocky streams that once existed with a proper environment to reproduce and lay eggs, dense sediment has starved the water of the oxygen the fish need to survive.
Next came a parasite discovered by biologists in 2020 that dealt another devastating blow.
“These are some of the cascading impacts we started to see,” Dr. George said. “That’s the situation we've been in for the past couple of years as we’ve seen a slow and steady loss of habitat for Laurel Dace.”
Dr. George refers to these compounded threats as an “extinction vortex.” The combined challenges have whittled the Laurel Dace habitat down to only two streams of the original eight. Youngs Creek and Bumbee Creek near Spring City, Tennessee are the only places they now inhabit, so even before the drought of 2024 things looked bleak for the Laurel Dace.
Dr. Anna George and rescue teams collecting endangered Laurel Dace from two streams in Tennessee. (Photo: Tennessee Aquarium)
Emergency Response
Due to the years of research on the Laurel Dace, the Tennessee Aquarium had a recovery plan that was already underway for nearly a decade. When the severe drought conditions hit the region in July of 2024, annual surveys conducted as part of that plan picked up the next critical threat to the species that would almost certainly wipe them out entirely.
“A graduate student from the University of Georgia has been working with us on some behavior studies that will help us in the recovery of Laurel Dace and he came back from some fieldwork and said, 'I'm really concerned about the levels of water in the creeks.' The fish do not seem healthy and the creeks were starting to dry up to where there were disconnected pools,” Dr. George said.
The only option for saving the few fish that were left was to collect as many Laurel Dace as possible and put them into human care at the aquarium until a long-term plan to restore them to their natural habitat was established.
“It was like, let's get some of them here so that we're not at risk of extinction for this species,” said Dr. George. “We continued watching the drought conditions throughout the summer into September. Unfortunately, we received no significant rainfall during that entire time, so we staged four other rescue missions from July through September, where we brought back just under 300 fish.”
The Tennessee Aquarium is leading the Laurel Dace rescue and conservation efforts with support and partnership from U.S. Fish and Wildlife Service, Tennessee Wildlife Resources Agency, and other academic and conservation partners. Funding is in place for both the immediate collection and care for the drought-stricken fish and the long-term recovery of the Laurel Dace with programs that incentivize farmers and landowners to make conservation-minded changes to their agricultural practices.
The Tennessee Aquarium Conservation Institute. (Photo: Tennessee Aquarium)
Keeping Up With Aquatic and Environmental Threats
While the immediate focus is on saving the Laurel Dace, Dr. Bernie Kuhajda, an Aquatic Conservation Biologist at the Tennessee Aquarium Conservation Institute, points to other successful efforts at saving aquatic species as a reason to have hope for this latest critical mission.
Dr. Kuhajda has studied endangered species of fishes throughout the Southeast United States for 40 years, and says that being proactive gives threatened fish the best chance for survival.
“We can be biologists and light our hair and fire and scream and run around and say, 'it's horrible, it's horrible.' Or we can do something,” said Kuhajda.
Lake Sturgeon populations are growing due to recovery efforts in Tennessee. (Photo: Tennessee Aquarium)
One recovery success story is the native Lake Sturgeon that once greatly inhabited the Coosa River system in Georgia and the Tennessee River system in North Carolina, Tennessee, Kentucky and Alabama. Populations of Lake Sturgeon disappeared by the 1970s due to commercial fishing for caviar and poor environmental management. Since 2000, a collaborative network of agencies enabled the restoration of native Lake Sturgeon with stocking efforts. The program has worked so well that there is now a reduction in stocking and the Lake Sturgeon will be monitored to see if they can reproduce naturally.
Native Southern Appalachian Brook Trout are making a comeback in Tennessee waters due to conservation efforts. (Photo: Tennessee Aquarium)
Another success story comes from the efforts to restore Southern Appalachian Brook Trout in Tennessee, the state’s only native species of trout. With the introduction of non-native rainbow, brown and Northern Brook trout into Tennessee waters they compete with the native species. Fisheries biologists use an intricate process to propagate the native brook trout, maximizing genetic diversity, then reestablish them in waterways protected with barriers that prevent invasive species from competing with them.
“The more genetic diversity you have, the healthier the population is and the better chance they have to handle those events that might wipe them out,” said Kuhajda.
A healthy genetic diversity helps species survive the man-made elements like habitat fragmentation that make fishes more vulnerable to the impacts of extreme weather events.
The Tennessee River is an example of this. The river is segmented by dams and oldmill dams preventing upstream migration. Species like catfish and bass are not as impacted as the other 235 species that rely on that migration for genetic health.
“They're still doing great in the tributaries to the Tennessee River, but they have lost that migration corridor in the Tennessee River to have gene flow between all these tributaries. So genetically, they're becoming less healthy over time,” Kuhajda said.
“If nothing changes fish will have to be physically moved from one stream to another to mimic migration, otherwise those species will eventually die out.”
Dr. Bernie Kuhajda releases Southern Appalachian Brook Trout into a Tennessee stream. (Photo: Tennessee Aquarium)
Sedimentation and pollutants are the other reasons why extreme weather events inflict such drastic consequences to freshwater aquatic life. Sediment going directly into rivers comes from a variety of sources stemming from poor agriculture, timber and construction practices that don't maintain silt fences and things like microplastics that were once only thought to be an ocean problem.
“It's the motor oil and transmission fluid and cigarette butts that wash in off our impervious surfaces in our city's parking lot, sidewalks and roofs,” Kuhajda said. “The water itself becomes a pollutant in urban situations because when that water hits those impervious surfaces, none of it goes into the ground.”
As water levels rise quickly after rainfall then retreat to extremely low levels, that sediment becomes trapped having a greater impact in smaller streams like those along the Cumberland Plateau. Over time, the impact transforms a habitat defined by bedrock and boulders into mud.
Fisheries biologists collecting Laurel Dace in the Bumbee Creek. (Photo: Tennessee Aquarium)
The Bigger Picture
The U.S. Fish and Wildlife Service, responsible for monitoring endangered species status, faces an uphill battle when it comes to staying ahead of potential environmental threats. The drought impact in Tennessee is an example of what many other states face when it comes to aquatic habitat threats.
“Tennessee is experiencing rapid growth in many areas, increasing both rates of habitat conversion and demands we place on water resources to supply growing industries and populations,” said Geoff Call, Fish and Wildlife Biologist for U.S. Fish and Wildlife Service. “The challenge is to grow our communities with an eye towards conserving the natural heritage that makes Tennessee attractive to live in and visit and provides clean water and air that people, fish, wildlife, and plants all need.”
When one crisis hits, like the drought on the Laurel Dace, there’s often more than one impact. In this case, the impact spread beyond just small mountain streams to larger waterways like the Duck River in Tennessee.
“The Duck River is recognized for being one of the planet's most biologically diverse streams, and reports of stranded mussels raised concern that the river, facing pressures from drought and water use in a rapidly growing part of middle Tennessee, might not support such a rich diversity of species into the future,” said Call.
The Barrens topminnow is another endangered aquatic species in Tennessee impacted by recent drought conditions. Every stressor causing repeated population bottlenecks impact a species’ genetic variation going forward and a diminished ability to adapt to future changes.
The U.S. Fish and Wildlife Service relies on several models to help it predict areas of anticipated development, growth impacts on species and habitats, and risk analysis to determine species with the greatest conservation needs.
“While we incorporate data about predicted changes in weather patterns and frequency or severity of extreme events into our assessments of species status under both current and predicted future conditions, a challenge we face is that most models don't provide data at spatial or temporal scales that are precise enough to predict effects on species and populations,” Call said.
For now, these forecasts are the best option available to develop strategies that reduce as many risks as possible. It is an ongoing challenge to stay ahead of threats to aquatic species, especially in a region that has experienced a drought and a major hurricane back-to-back in the same year.
Laurel Dace tanks at the Tennessee Aquarium. (Photo: Tennessee Aquarium)
The Future Outlook for the Laurel Dace
Even with all hands on deck and emergency efforts in place, the long-term outlook for the Laurel Dace is uncertain as biologists take a day-by-day approach.
“Our plan has been, let's assess what's happening on the ground before we decide what we will be doing next,” Dr. George said. “We are going to hang on to the fish in our care until rain returns. We have installed trail cameras that send us pictures from the creeks every 30 minutes, so we can keep an eye on what the habitat conditions are like for these fish.”
Dr. George said there are several paths in front of them. First, once rains and stream waters return to acceptable levels, they could release the collected fish back into the wild where they can spawn in their own natural habitat. The second option is to enable the Laurel Dace to spawn in the care of the Tennessee Aquarium if conditions are not right to return them to their natural environment. Biologists can raise the offspring and return them to the creeks when conditions enable survival.
The third option is to return a large group of the Laurel Dace into the streams when conditions are right but hold some back to establish an arc population if they feel the extinction risk is too high.
“We hold individuals at the aquarium and keep a population spawning and keep taking care of that population for the time period that we think is necessary to fix other habitat concerns so that we can release Laurel Dace into more than just the two creeks where they're currently found,” Dr. George said.
The Laurel Dace species still faces an uphill battle for long-term survival. (Photo: Tennessee Aquarium)
Despite the seemingly uphill battle still ahead for the Laurel Dace, the biologists working around the clock to save them see a silver lining.
“I think it is moments like this that give us hope to continue tackling these large problems,” said George. “We're not going to get anywhere in conservation if we decide we can't do anything, the problem's too big, and we walk away.”
Taking small steps that collectively make a big impact is the key to changing a survival trajectory. The tiny Laurel Dace, with so many odds stacked against it from the moment it was discovered, is proof positive that nature is resilient when given a chance. That is the motivation that keeps biologists and conservationists pushing forward against all the odds.