The Middletown Press (Middletown, CT)
Oyster cages help fishing industry
GoPro cameras watch animal behavior
MILFORD — As oyster farming has evolved to using stacked cages to grow more of the shellfish on the same area of seabed, researchers are wondering how fish are responding to the artificial structures.
So far, it seems the fish like the oysters’ breeding cages just fine.
In a two-year project, marine scientists at the Milford laboratory of the National Oceanic and Atmospheric Administration’s Marine Fisheries Service are using off-theshelf GoPro cameras to record the activity of black sea bass, cunner, tautog (blackfish) and scup, which are common to temperate reefs along the Atlantic Coast, such as the one near Charles Island.
“The goal of this work is to look at how aquaculture gear provides habitat and ecosystem services (food and shelter) for recreationally and commercially important fish,” said Renee Mercaldo-Allen, a research fishery biologist at the Milford lab near Silver Sands State Park and co-principal investigator on the project with Julie Rose.
The team from the Milford lab is assisted by the NOAA Commissioned Officer Corps, which Lt. Cmdr. Keith Golden called
“the seventh uniformed service, under the Department of Commerce.”
Golden, one of two divers on last week’s trip, said, “One of our tasks as NOAA divers is to support other units that need divers.”
Throughout the summer, they head out on Tuesdays to mount two cameras on four cages at an oyster farm west of Charles Island and on four T-shaped platforms attached to boulders near the reef to observe the fishes’ behavior near natural structures.
The cameras, using Blink time-lapse controllers, are set to record 8 minutes of video each hour from 7 a.m. to 7 p.m. Wednesday. On Thursday, the crew picks up the cameras so the video can be studied.
“It’s a lot of field work to get the video and then it’s a lot of lab work to review and score the video,” MercaldoAllen said. Scoring involves counting the fish, identifying species, behaviors and their life stages, she said.
“If we can demonstrate that we’re using these cages for habitat, then that’s very important for the constituents along these waters,” she said. “We’ve noticed that oyster cages support fish of multiple life stages. We’ve seen a variety of behaviors: feeding, sheltering, something we call station keeping, which is stay[ing] in one place.” They’ve also seen courting behavior around the cages, she said.
The project stemmed from observations by local shellfish growers, MercaldoAllen said, who are increasingly using the steel oyster cages “because you can grow oysters on a smaller footprint.”
Recording video at the boulders, located in a less dense area of the reef, is useful in order to compare the fish there, which tend to be smaller, to those that hang out near the oyster cages, she said.
The oysters have been loaned to the Milford lab by the Noank Aquaculture Cooperative and will be returned once they’re fully grown, she said.
Lt. Erick Estela of the NOAA Corps and the captain of the 49-foot Research Vessel Victor Loosanoff, said, “The work we do is very rewarding. Ninety percent of the seafood in the U.S. is imported. … All the fish we are researching are commercial so … we are providing more information to the farmers.”
Tuesday was a warm, clear day and the divers hoped to be able to put cameras on the T-platforms and do some maintenance. “We’ve had very poor visibility this year, and some of the tasks really require you to see what you’re doing,” Mercaldo-Allen said. Magenta filters are put on the camera lenses to filter out the green color created by vegetation in the water.
Golden and Mark Dixon, a biological lab technician and the second diver, spent more than a half hour on the seabed. While the water was “pretty murky,” according to Golden, “it wasn’t difficult. … When you can’t see, it just adds a whole ’nother realm of being able to see each other and then being able to see what you’re doing.” Golden said he and Dixon couldn’t see more than 2 feet.
“It’s like going to work in the morning blindfolded; that’s how it is,” Golden said.
“For the most part the dives have gone pretty smoothly but today we did some extra tasks,” Dixon said.
After the dive, the Victor Loosanoff, named for the first director of the Milford lab, headed to the oyster farm, where Gillian Phillips and Dylan Redman, both biological lab technicians, hauled the cages out of the water and attached two GoPros to each, then lowered them back into Milford Harbor.
“We get to take what fishermen have told us they see on cages and actually capture it, and we’re beginning to quantify it as well,” Phillips said. “Oysters are very important to aquaculture and to the Connecticut economy, but if we can also demonstrate that this established growing process also benefits fish such as black sea bass and blackfish … then that’s very important for the constituents along these waters.”
After the cages were taken off the deck, Phillips picked up some small crabs, which she threw back, and a couple of tiny fish, probably recently hatched black sea bass, that she put in a plastic bag for taxonomist Paul Clark to identify later.
The crew also took water samples for biologist Yuan Liu to analyze for environmental DNA in fish scales and feces. “She’s taking water samples off the reef and at the shellfish farms,” Mercaldo-Allen said. “This is providing us with added information about fish that are in the area” but that might not show up in the videos.
It’s experimental “because we’re working in a relatively small embayment, we want to see if eDNA is sensitive enough to detect differences in fish communities between different sites,” MercaldoAllen said. It’s a growing field because it’s less expensive than catching fish by dragging nets.
Also on the boat, interns Deaven Maull, a senior at Washington College in Maryland from Delaware, and Max Mauro, a junior at the University of Maine, tested the water for temperature, salinity and dissolved oxygen.
“I think my favorite part is being part of an actual research project and seeing how it’s done,” said Maull, who is majoring in environmental science and wants to go into wildlife ecology and conservation, ideally in Africa.
“I enjoy the aspect of getting to know a bunch of new things from a bunch of super-smart people,” said Mauro, who is from Milford and who attended the Bridgeport Regional Aquaculture Science and Technology Education Center. Also and environmental science major, he said, “I really wanted to try it in the field and try to get a grasp of what industry practice is.”
First mate Dylan Redman, a biological lab technician, designed the T-platform, which includes a current meter and data logger to measure light and temperature. “We redesigned them a couple times … to get the cameras set at the right angles,” he said. Radiator hose was used because it holds its shape and the steel pipes came from Home Depot, he said.