Hatching a Way Forward The Work of the Natchitoches National Fish Hatchery

Found only in Rapides and Grant parishes, the Louisiana pearlshell mussel was listed as federally endangered in 1988. That listing was downlisted to threatened in 1993. In 2010, the Natchitoches hatchery started researching methods to propagate Louisiana pearlshell mussels in the lab.

Above ceaseless bubbling in the algae-pungent lab, conversation turns to the sex lives of mussels.

Brett Hortman and Lindsey Adams lean over an oxygenated bath, their backs to cinderblock walls lined with 60 aquariums. They discuss gene mixing, inbreeding, “the process of impregnation.” Adams, a fisheries biologist, dips her hand into the 500-gallon bath, or “grow-out system,” and scoops a kidney-shaped mussel from the bottom. Holding it in one palm, she strokes the slightly corrugated shell and speaks its name, Louisiana pearlshell, the white whale of Louisiana mussels, a species so rare it’s found only in two parishes, Rapides and Grant.

“We’re the only ones working with these mussels,” says Hortman, manager of the Natchitoches National Fish Hatchery. The Louisiana pearlshell is one of several endangered or threatened species that he, Adams and the other four staff members here work to recover. Founded in 1931, the state’s sole federal hatchery also continues its original purpose: to raise fish for recreational purposes.

Two miles south of downtown Natchitoches, located on 100 acres where Cane River Lake makes a 90-degree turn from its due south course before shifting northeast in the general direction of Washington, D.C., the hatchery’s facilities are at once makeshift and cutting edge. In five labs devoted to species that include Louisiana pearlshell mussels and gopher tortoises (both threatened species), and alligator snapping turtles and paddlefish (species of concern), the staff, along with volunteers from Northwestern State University, work seven days a week, taking turns on weekends, and never closing during government shutdowns. “There’s always work,” Hortman says.

 That work includes maintaining the property’s 52 ponds, each approximately one acre, where the staff culture and raise largemouth bass, bluegill, redear sunfish, channel catfish and hybrid striped bass. The fish remain in the ponds until they reach target size, typically after two or three months. Then the Natchitoches facility — one of 69 federal hatcheries throughout the United States — partners with the Louisiana Department of Wildlife and Fisheries and the state hatchery in Woodworth to transport the fish, 75% of which remain in local waters.

Inside the mussel lab, Hortman and Adams move between the aquariums and the oxygenated bath. The Louisiana pearlshell received a federally endangered listing in 1988, sparking the state to begin a recovery plan. Since 1990, the species has been discovered in new locations, typically in shallow (one to two feet deep), narrow (16 feet wide, maximum) sandy- or small gravel-bottomed spring-fed streams. This led to a downlisting from endangered to threatened. Recently, however, the Louisiana pearlshell population has declined.

“We’re not exactly sure what’s driving this,” says Adams. Potential factors may include sediment runoff from farmlands and tree clearing, which opens canopies and increases water temperature. To combat the decline, in 2010 the Natchitoches hatchery began researching methods to replicate the way the Louisiana pearlshell reproduces and grows in the wild. Propagation of the mussel began here in 2018.

“An adult mussel’s chance of success is very small,” Hortman says. “We’re trying to develop a technique from the ground up.” Adams approaches the grow-out system. Born and raised in Michigan, she began her field work by studying freshwater mussels. Before beginning her role at the hatchery, she hadn’t heard of the Louisiana pearlshell. “It’s really a whole world that no one knows exists,” she says, turning as Hortman opens a small refrigerator. Inside are several glass flasks filled with algae, which automated pumps deliver to the oxygenated bath. Set under 71 degrees, the bath temperature mimics a spring-fed stream. “We’re not sure how fast they grow in the wild,” Hortman says. “It still takes us about two years to get them to around 30 millimeters, a size where we believe they can survive in nature.”

Fisheries biologist Emmet Guy makes regular rounds in the gopher tortoise lab. The Nature Conservancy deems these tortoises a keystone species and “about as charming as a tortoise can get. Originating 60 million years ago, it’s one of the oldest living species on the planet and the only native North American tortoise species east of the Mississippi. River.”

If Adams didn’t know about the Louisiana pearlshell before assuming this work, she certainly didn’t know about its twin. The two species of Louisiana pearlshell bear such close resemblance that even after five years of study she finds them indistinguishable. “Each species has a genetic component,” she says, “and they don’t mix.” The hatchery doesn’t mix them either. The Red River, however, does. On each side of the Red are host fish, in the case of the Louisiana pearlshell, grass and chain pickerel.

“These host fish do all the work,” Adams says, noting that Louisiana is also home to more than 60 species of Unionidae mussels, including half a dozen that live alongside the pearlshell. Unionidae mussels entice the host fish by displaying a lure from their shell. The lure looks like a small fish. When that bigger fish approaches, the mussel releases a bloom of glochidia larvae. “They’re 70-100 microns when inside the adult mussel,” Adams says. “1,000 microns equals one millimeter. Under a microscope, they look like Pac-Man.”

The larvae latch to the fish gills, occasionally a fin, and for the next 35 to 50 days, they triple in size to become juvenile mussels before releasing themselves into the sediment, where they grow into adult mussels. Then the whole process repeats itself.

“Their life cycle is mind blowing to me,” Adams says. “It’s all about timing.” Work inside the mussel lab strives to replicate those natural rhythms. So does the research next door, where fisheries biologist Emmet Guy maintains the gopher tortoise lab.

Each spring, the hatchery team travels to the De Soto National Forest in Mississippi to collect, on average, 60 gopher tortoise eggs. Once back at the hatchery, they place the eggs in a chicken egg incubator for nearly three months. The staff then moves the tortoises to tubs and raises them through the period when in nature their soft shells make them vulnerable to predators. Guy opens a refrigerator and removes a plastic container of salad mix and commercial tortoise food that resembles olive tapenade and prepares what you might pay $25 for at a trendy New Orleans restaurant.

Such meals come five days a week for these 90 tortoises. Half are between three and four months old. The other half have reached their first anniversary in the lab, their shells now hardened. Here, with a steady temperature of 70-76 degrees, the tortoises stay hungry, growing at twice the rate they would in nature.

“You try to get them through that early period,” Guy says as he listens to the steady scratching, like fine sandpaper over wood, emanating from each tub. For several seconds, it holds steady. Then, seemingly all at once, the scratching ceases. A few moments pass before the chorus resumes. “They like to scratch,” Guy says. “And they like to burrow.” Thus the name. With forelimbs like clawed shovels, a gopher tortoise that fits in Guy’s palm can send sand flying out of its tub and several feet across the room. “I’m constantly cleaning up after these guys,” he says, searching for a broom, “and I’m constantly refilling their sand.”

All the while, the tortoises eat. They grow. And after two years, Guy and the hatchery team transport them back to the same location where they began. Once home again, they can become 16-20 pounds and live to age 90.

“They provide an entire ecological system,” Guy says. “By helping these guys, we help a whole habitat.” The Nature Conservancy estimates that 300 species benefit from the survival of the gopher tortoise and its burrows, including eastern indigo snakes, gopher frogs, and hundreds of rodents and invertebrates that seek refuge from predators and fires in the tortoise’s tunnels, which can extend to 40 feet long and 10 feet wide.

(Left) Featuring species such as paddlefish and albino catfish, the hatchery aquarium is open to the public Monday-Thursday from 8 a.m.-3 p.m. Opposite Fisheries biologist Lindsey Adams inspects host fish tanks in the mussel lab.

Once finished sweeping sand, Guy exits the tortoise lab to check on the alligator snapping turtles. Inside this facility, he finds Hortman inspecting tanks. In fall 2023, when Hortman awaited news about whether the snapping turtle would move from the federal list of threatened to endangered (a decision that has still not been made), he and the team released the largest alligator snapping turtle they’ve ever housed at the hatchery, a 167 pounder. 

Native to the Southeast U.S., alligator snapping turtles live in rivers and streams that feed into the Gulf of Mexico. Each year in early April, the University of Louisiana at Monroe sends faculty and students to monitor nests and harvest alligator snapping turtle eggs from two of the state’s national wildlife refuges, Black Bayou Lake and Red River. UL Monroe incubates the eggs and then delivers the snapping turtles to the Natchitoches hatchery. Here, snapping turtles eat and grow for two years before the staff returns them where they were collected.

Alligator snapping turtles are the largest freshwater turtles in North America. Males can grow to nearly 250 pounds, with shells sprouting horny scutes that resemble alligator skin. “The snapping turtle … has a reputation for being an aggressive monster on land,” reports the Menunkatuck Audubon Society. “But consider this: Most turtles are able to withdraw into their shells when threatened. The snapping turtle cannot because, although its top shell, the carapace, is large, its bottom shell, the plastron, barely covers its underside.”

Like those gopher tortoises, they have soft shells when young, making them vulnerable to prey. Unable to fully retreat, the young simply play dead. Guy lifts one from the tank. Immediately, it goes limp in his hand. “That’s their best chance of survival,” he says. As they age, their shells harden. Their bony beak, that famous snapper, grows and becomes their defense. Alligator snapping turtles also have their own lure, a red tongue they wiggle to mimic the movements of a bloodworm. The snapping turtle rests at the bottom of a riverbed, mouth open, to tempt prey, and then the beak-shaped mouth snaps.

Outside the alligator snapping turtle lab, Guy fills a bucket to feed catfish at one of the ponds while Hortman checks on the hatchery aquarium. Inside the free, self-guided exhibit, a father and daughter inspect the tank filled with paddlefish, yet another of the hatchery’s priorities. Among the aquarium’s exhibits is a history of the Caddo Tribe, original occupants of this land. In 1930, when construction began here, builders realized they were working on a burial site. They collected artifacts and sent them to the Smithsonian and Northwestern State University. In 2008, those artifacts were repatriated. 

The tribe’s history, and the near century of work at the hatchery, is something that Natchitoches born and bred Hortman understands and respects. He’s made this his life’s work. While a student at Northwestern, he volunteered at the aquarium. After graduating in 1996, he began a full-time role here as a fisheries biologist. Later, he left to work at various national wildlife refuges in Louisiana, returning as hatchery manager in 2019. “It’s definitely rewarding to know you’re making a difference for not only one or two species but also to know that if species like the gopher tortoise do well, they will benefit others,” he says. “That’s why we do it.”