Sensors count herring hatchlings at Brewster run
By Rich Eldred reldred@wickedlocal.com
Posted Jul 29, 2017 at 6:31 AM
BREWSTER — No longer can little herring sneak out to sea anonymously. Facial recognition is being applied at the Stony Brook herring run in Brewster.
Actually, you can’t see the smiling faces of happy herring as they fly past the sensors by the hundreds every few seconds. But the idea is to use the latest technology to count the hundreds of thousands of inch-and-a-half long herring swimming and being carried downstream by the current after hatching in Walkers and Upper Millpond.
“A new underwater camera was installed where the counter used to be,” explained Jo Ann Muramoto, the director of science programs at the Association to Preserve Cape Cod, who monitors herring runs all over Cape Cod.
“This is research for a master’s thesis to test the underwater camera and software to count juvenile herring passing through. It has infra-red sensors so it can run at night and we’ll use the software to get a quantitative count. There is very little information about juvenile herring.”
The adult herring swim upstream in the spring passing through the rocky Stony Brook run (about 130,000 this year) and spawn in the ponds linked to the run. The juvenile herring, under two inches in size, swim out in great numbers in July and August.
“They’re an important part of the population we don’t know much about,” Muramoto said. “We’ll be happy to fill the gap.”
‘They’re coming down strong now,” noted Herring Warden Doug Erickson. “Usually it dies off in mid-July and then picks up again. We see them as late as December.”
Christopher George of Antioch University is the intern/thesis candidate conducting the study, working with Dr. Rob Vincent at M.I.T. Sea Grant, and he was in the stream earlier this week with a maul plowing the sand to lay the cable connecting the camera to the laptop computer which was installed inside the grist mill.
Inside the ancient mill you could look over the millstones to see the fish swimming past on the monitor. They were little slivers of light shooting across the screen. The software records all the data.
The camera is housed in a box in the channel the fish pass through. It’ll be there for eight weeks. The APCC installed an electronic counter this spring and will compare that data with the volunteer counts that have been ongoing for years.
“We think this has the potential to answer a big question about the rate of spawning,” said Andrew Gottlieb, executive director of the APCC. “This will help us manage the stock a little better. This is the type of project an organization like ours has the ability to do, innovation beyond a town’s capability.”
“Anything they can do is going to help,” added Dana Condit, the longtime head of Brewster’s Millsites Committee. “Jo Ann and I were just talking. We do all of this to keep the run open and the fish are being taken offshore.”
Once they’re a sea the river herring mingle with Atlantic herring and get swept up by large trawlers fishing for the ocean species.
“Overall the numbers really haven’t recovered,” Condit noted.
Masschusetts put a moratorium on harvesting herring in the rivers in 2006 and it is still in place as the species struggles to recover from overharvesting. The Brewster run peaked in 2014 with 253,000 fish but has since fallen back.
George was done working in the water and had time to discuss his project. He originally was working at Tidmarsh farms in Plymouth, on a herring run restoration tracking the adults with P.I.T. tags (passive inductive telemetry). This project, to complete his degree, targets juveniles.
“It’s using facial recognition technology to count the herring. We’re testing the equipment, gathering underwater data and preparing a feasibility study for the APCC,” George explained. “They go tail first across the current so we positioned the camera where the current is fast enough they can’t go back up. It’s amazing video.”
He’ll be trying different software to see which is most effective at counting.
“This eliminates the need for net capture (to estimate population size),” George said. “And we can compare across ponds. We had to figure out how to adapt to a USB camera. The viewing platform is a surveillance camera system. We will work though the video data with the available programs for facial recognition, motion sensing.”
Stony Brook is one of the biggest herring runs on Cape Cod so there will be lots of data.
“This is an ideal spot. The water is clear. We’re fortunate everyone is so interested and agreeable,” George said.
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