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Sleepless in Blue Spring

Catfish on manateeIf you’ve ever spent a sleepless night swatting mosquitoes, you’ll understand the manatee’s plight.

Longing for rest in the warm waters of Volusia County’s Blue Spring, Florida’s manatees are being harassed by armored catfish. The invasive species attach their sucker mouths to the manatees’ skin and graze for algae, as illustrated in the photo at right.

“So instead of resting, manatees expend precious energy trying to dislodge the catfish,” says Melissa Gibbs, Ph.D., associate professor of biology and director of the Aquatic and Marine Biology Program. “Just as you or I would swat at a pesky mosquito, the manatee twitches and flips to throw off the harassing catfish.”

Native to the Amazon basin, Loricariid catfish arrived in Florida in the 1950s. They gradually spread throughout the state.

“Many people call them plecos and purchase them from aquarium stores to eat the algae out of fish tanks,” Gibbs says. “Trouble is they can grow to over two feet long. When the fish get too big for the tank, people want to get rid of them.”

Reluctant to kill the catfish, aquarium owners released them into the environment, and the problem began. Already stressed by human activity, pollution and cold temperatures, the endangered Florida manatee doesn’t need any additional harassment.

“It’s not too different from the python problem currently plaguing the Everglades,” Gibbs adds.

Armored catfish removal

Students at Stetson help to remove the invasive armored catfish from Blue Spring where manatees like to winter.

Accompanied by students, park rangers and biologists, Gibbs has removed 6,300 invasive catfish from Blue Spring over the past 10 years. Once a month she slips into two wet suits (“one short and one long, because it’s cold”) and snorkels in the spring’s clear water to collect data for reproduction, age and growth studies.

“We’re never going to totally get rid of them, but if we figure out more of their biology, we might be able to control the catfish population a bit,” she explains, adding that one more year of data must be collected before publishing the results of her reproduction studies.

“We are thrilled to work with her on this research,” says Blue Spring Park biologist Megan Keserauskis. “We sometimes snorkel with her or follow in the canoe, collecting monthly samples. We also walk along the boardwalk, educating visitors about the invasive catfish research.”

Gibbs admits her colleagues “come out of the woodwork when they hear we’re going on a catfish expedition. Usually I have one student every year who gets really good at it, and we can remove several hundred fish in one day.” She points to former student Justin Walker ’12 (Aquatic and Marine Biology), who was extremely proficient at removing invasive fish while participating in the senior research program.

“Justin established a reputation and interned at the Fish and Wildlife Commission. Now he’s working for them,” she says. “My students definitely get a lot of hands-on experience collecting and presenting data.”

by Renee Garrison