Quenton Tuckett likes to go fishing with his buddy in Florida’s Tampa Bay. He often finds himself chasing fish in the shallows, which are places he knows well, thanks to his work at the University of Florida’s Tropical Aquaculture Laboratory. Not long ago, he was in the shallows trying to help jump-start the population of bay scallops. They like to hide in the same seagrass that a lot of fish do.
For years, he’s seen prop scarring in the seagrass — U-shaped valleys left behind after a propeller digs a bare patch into the bottom. These are real scars that seagrass beds have trouble healing on their own, with repairs generally requiring human intervention that costs time and money. Tuckett knew, just from looking around, that the problem was widespread, but until recently, he had never tried to quantify it.
“Traditionally, the way people would identify and quantify prop scars is to look at digital [overhead] imagery and circle the areas,” Tuckett says. “It’s lighter, kind of whitish, because it’s sand against this darker background of the grass. You can actually identify it from a lot of images pretty easily. But it takes a long time to trace those, and we wanted to do the entirety of Tampa Bay.”
Working with scientists from Auburn University and the Tampa Bay Estuary Program, he turned to artificial intelligence. A program they created has identified nearly 24,000 prop scars in Tampa Bay so far, about one for every four registered boats in Hillsborough and Pinellas counties. That work will now become the basis for outreach programs to boaters on Tampa Bay, and potentially beyond, about ways to limit the damage that props can do to seagrass.
“It would be great if people just knew what to do,” he says. “If you’re going to the shallows, use the push pole. Trim up. Go slower. There’s a lot of ways that you can move around in the shallows safely and not damage the seagrass.”
The researcher at Auburn University who designed the machine-learning model is Katelyn Lawson, a geographic information systems analyst who also holds degrees in zoology, fisheries and aquatic science. Like Tuckett, she understood that there were high-resolution photos available of Tampa Bay, taken from planes overhead. She wanted to know if a computer could stitch together those images into one large visual of the bay, then learn to spot prop scars from that combined image.
As it turned out, the answer was yes. Lawson used a program from Esri, which makes mapping and analytics software, to create a model that worked. She first built a training data set, which means she personally highlighted prop scars in the imagery to teach the computer program how the damaged seagrass looked. This type of learning is more complex for a computer than it might sound; in some sections of the bay, the scars are more teal, while in other spots, they’re more whitish.
“I did about 200 of those,” Lawson says. “After that, you can create a model in the software so the computer will look for more of these.”
The computer then went to work for 16 days. When it finally spit out a result, she says, it was “pretty astounding. It’s crazy, seeing how bad all of it is. When you see all the red lines on the screen, it’s like, whoa.”
The model could be replicated, she says, anywhere that high-resolution overhead imagery of a waterway is available. As for Tampa Bay, Tuckett says the next step is to use the information to help boaters understand how bad the problem is, and what they can do to help. The plan is for an educational initiative that includes billboards and more, to teach boaters the importance of watching their prop depth in the shallows.
For instance, Tuckett says, his fishing buddy is a member of Freedom Boat Club, which allows boaters to rent a ride instead of buying the boat.“We’re working with them to get some outreach going,” Tuckett says. “A lot of the people using these clubs aren’t as experienced on the water. We’re working with them on their training manual about how to avoid scarring the seagrass. It’s a great organization to partner with.”
The steps boaters can take to protect seagrass are pretty simple, he says. Use navigational aids to stay in the channels whenever possible. Know when the tide will be low. If you find yourself boating in the shallows like he does when chasing fish, slow down and lift the prop. Use a push pole, not the engine, to move the boat around. Wear polarized sunglasses so you can better spot seagrass beneath the hull in the first place.
“By all means, if you want to be in the shallows, then be in the shallows, but know how shallow it is,” he says. “A lot of times, these environmental problems are really hard to handle. But if you’re not chewing up the seagrass, it’s just so obvious that it helps.”
This article was originally published in the April 2023 issue.
