Among freshwater biologists, few things trigger louder or more distressing alarm bells than watching a waterway dry up during a prolonged drought. That’s especially true when the stream that’s disappearing is home to one of America’s most-imperiled fish.
In late July, reports of dramatically withered streams atop Walden Ridge north of Chattanooga spurred an emergency rescue operation to prevent the extinction of the federally endangered Laurel Dace, which scientists consider to be among the 10 most-at-risk fish in North America.
This effort was carried out by representatives from the Tennessee Aquarium, the U.S. Fish and Wildlife Service and the University of Georgia’s River Basin Center in coordination with the Tennessee Wildlife Resources Agency. In all, 105 adult Laurel Dace were removed from dangerously dry streams and successfully relocated to the Tennessee Aquarium Conservation Institute (TNACI) near downtown Chattanooga.
All but one of the collected fish survived the relocation and are now thriving in temporary human care, where they will remain until conditions in their few native streams are sufficiently improved for them safely to be returned.
“The Laurel Dace are doing great,” says Abbey Holsopple, the Aquarium’s recovery biologist. “They’re eating like crazy. They almost seem relieved to have fresh, clean water and plentiful food sources, which they weren’t getting in the wild during the drought.”
Fig. 1 Some of the 105 adult Laurel Dace rescued from drought-ravaged streams on Walden Ridge swim in temporary holding systems at the Tennessee Aquarium Conservation Institute (TNACI). They will remain in human care until conditions in their native streams are habitable once again.
A risky rescue
That this relocation proved so successful was by no means a foregone conclusion to the team as they embarked on their rescue effort.
Tugging on waders before grabbing nets and buckets with oxygenating bubblers, their descent from a rutted dirt-and-gravel backroad toward the creek was made with grim trepidation tempered by a growing sense that this risky operation was the right call.
“I was pretty shocked by the condition of the stream,” Holsopple recalls. “I had been there sampling about a month before we did the rescue, but when we got to the site, I was shocked by how much it had changed.”
The few remaining pools were little more than glorified puddles, the remaining water rarely deep enough even to moisten the rescuers’ socks. What fish they held — more often than not the similar-looking Western Black-nose Dace — swam bunched together, drought-stranded in conditions that were dismally shallow and often sediment-choked.
Even if it’s made in the species’ best interest, any decision by wildlife managers and biologists to remove an animal from its home is not entered into lightly, especially for animals as endangered as the Laurel Dace.
Relocation carries inherent dangers, from injuries and stress during transport to adverse reactions caused by different foods, temperature or water chemistry while in human care.
On the other hand, drought conditions can lead to higher water temperatures, lower oxygen levels, reduced access to food and crowded living conditions, all of which are daunting challenges for fish to overcome.
“The fish in the stream can get trapped into these pools with nowhere to go,” Holsopple says. “Imagine if you were at a concert and you’re surrounded by people on every side of you. You’re rubbing up against each other. It’s hot; it’s uncomfortable.
“Spending every single day of your life with that many people around you just increases the stress and can lead to issues like disease.”
Fig. 2 Once a free-flowing mountain stream, one of the last two waterways known to support a population of Laurel Dace has been drastically impacted by drought, reduced to isolated pools separated by vast stretches of bare rock.
Fig. 3 [Left] Tennessee Aquarium VP, Chief Conservation & Education Officer Dr. Anna George, left, and Senior Aquarist Avery Millard examine a Laurel Dace rescued from an all-but-dry stream in a viewing aquarium. [Right] A Laurel Dace collected from the stream in a portable viewing aquarium. More than 100 of this critically endangered minnow were collected and rehoused in human care during this operation.
Preventing extinction
Weighing the risks of removing Laurel Dace against the danger of letting it ride out the drought, the Aquarium and its partners decided the minnow needed their help more than it needed to be left alone.
“When we saw the conditions the Laurel Dace were living in, we were not comfortable leaving an extremely endangered species to try to survive this event on its own,” says Dr. Anna George, the Aquarium’s vice president of conservation science and education.
“When you’re a conservation biologist, you’re working with these critically endangered species, which is kind of like having a patient who’s in the ICU. What really weighed heavily on us was knowing that, given how critically endangered the Laurel Dace is, inaction could have led to the permanent extinction of this species.”
With its golden-striped flanks, red belly, highlighter yellow fins and crimson lips, the Laurel Dace is like a living statement piece for the under-celebrated beauty of freshwater fish.
The U.S. Fish and Wildlife Service first identified the Laurel Dace as a species potentially in need of protection under the Endangered Species Act in the early 2000s. It posted notice that it was elevating the Laurel Dace to candidate status for listing in 2007. The Laurel Dace’s endangered listing was finalized in 2011, and the Service has been monitoring the remaining populations along with the Aquarium and other partners ever since.
As recently as 2012, Laurel Dace were still found in five streams flowing along Walden Ridge, but 12 years of rampant habitat degradation have reduced the species’ range to a pair of waterways.
Fig. 4 [Left] Taken during a period of normal rainfall in June 2020, Tennessee Aquarium Conservation Institute scientists sample for Laurel Dace in a stream atop Walden Ridge. [Right] In the same location in July 2024, a prolonged drought had reduced the waterway to a string of disconnected, shallow pools with fish living in cramped confinement.
The ghost of a stream
One of the Laurel Dace’s last remaining refuges — and the site of the rescue operation — is normally an idyllic stream flanked by thickets of the blush-blossomed trees for which the Laurel Dace is named.
On the day of the rescue, however, it was a desiccated ghost of itself.
Despite overcast conditions and a light drizzle that did little more than make the rocky creek bed treacherously slick, it quickly became clear that this was now a creek in name only. Where water once flowed freely were now a smattering of shallow, stagnant pools separated by spans of exposed boulders sometimes hundreds of feet wide.
Moving methodically in the direction water normally would be flowing, the rescuers evaluated each isolated pool to determine if the little water that was left was deep enough to bother sampling.
In most cases, it wasn’t.
When it was, the rescuers often were forced to contort themselves into odd positions — awkwardly straddling boulders, reaching under rocky ledges, splashing their open hands through inches of water — to ensure any fish were herded into their outstretched seine nets.
In such unhospitable conditions, every Laurel Dace the rescuers were able to recover felt like a tiny victory, Holsopple says.
“Everybody had a really strong sense of responsibility for each individual fish,” she says. “The importance of ensuring the health and wellbeing of every single individual was magnified just because of how few of them there are left in the world. No member of our team took that lightly.”
Raising the alarm
Christian Swartzbaugh, a graduate student from the University of Georgia, participated in the rescue and was the first to notify other biologists to how severely the drought was impacting the network of small, first order waterways atop Walden Ridge. Throughout the summer, he often was in the field as part of his research at TNACI focusing on the Tennessee Dace, a threatened species closely related to the Laurel Dace and which is found in many of the same stream systems.
During a trip earlier in July to collect Tennessee Dace in a stream near the site of the rescue, the conditions Swartzbaugh observed sent up red flags. Looking down on the Laurel Dace’s drained waterway on the day of the recovery, he realized how important sounding that alarm had been.
“As soon as we stepped out of the vans at the site, I had no doubt that what we were doing was absolutely necessary and in the best interest of the fish,” Swartzbaugh says. “They were clearly in a very perilous situation.
“While the first best place for a Laurel Dace would be in a healthy creek, the second best place would be under the care of our propagation staff at TNACI.”
Normally, the Endangered Species Act prohibits the removal of federally endangered animals from the wild, but the Aquarium is permitted to do so as part of its participation in Laurel Dace recovery efforts. This latest rescue called for the relocation of more individuals than allowed under that permit, but U.S. Fish and Wildlife Service biologists are empowered to make exemptions in dire cases to prevent damage to a species.
U.S. Fish and Wildlife Service Conservation Delivery Coordinator Geoff Call took part in the rescue effort and helped coordinate with state and regional wildlife managers to ensure the collection was conducted in compliance with regulations.
That the fish were safely collected within a couple of hours and overwhelmingly survived relocation to TNACI is not a surprise, given the abundance of preparation made on the front end, Call says.
“The collections were done in the safest way possible for the fish and to give them the best chance of successful transport, which gave me confidence that we would get the best outcome that could be hoped for,” he says. “The fact that we ended up losing only one out of 105 fish is a testament to the capabilities of the staff from the Aquarium who came and worked with the Service to do the rescue.”
Fig. 5 Scientists at the Tennessee Aquarium Conservation Institute's freshwater field station near downtown Chattanooga evaluate the health of Laurel Dace rescued from streams atop Walden Ridge. Of the 105 adults collected during this collaborative effort, all but one survived their relocation into human care.
Foster care
Ultimately, the goal of the rescue is not to house the Laurel Dace permanently in human care but to offer temporary sanctuary to ensure their survival during the drought. How long this foster care arrangement lasts is largely dependent on the weather.
Despite scattered precipitation events throughout Southeast Tennessee in the last few weeks, substantial rain hasn’t fallen on Walden Ridge since early June. With no rain in the long-range forecast, drought conditions may worsen in weeks to come and could linger until the return of wetter weather in the late fall or early winter.
Scientists and representatives of the U.S. Fish and Wildlife Service are conducting regular site visits to the streams on Walden Ridge to keep an eye on conditions in case waterways improve faster than anticipated.
Whatever the timeline for the Laurel Daces’ return to the wild, their homecoming will be a high-water mark for the biologists who are so invested in the species’ survival, Holsopple says.
“Days like the day when we get to bring the Laurel Dace back to the stream are the ones that keep us going,” she says. “We get to feel the success of actually protecting this fish from something that could have caused its extinction and feel the joy that that comes from saving them for the future.”
