After 40 years, a quest for winter flounder

Apr 25, 2023 | Plumbing the Depths

Mike Blanco, seasonal technician with Massachusetts Division of Marine Fisheries, prepares to take a water sample in Waquoit Bay.

By Doreen Leggett

John Logan, fisheries biologist at the Massachusetts Division of Marine Fisheries, slowly motors a skiff down Child’s River in Falmouth to check the last net of the day. Mike Blanco, wearing camouflage waders, is ready to hop out and check for winter flounder, but hopes aren’t high.

“Last week we got totally skunked,” said Logan.

“Except for the pipefish,” volunteered Blanco with a grin, referring to a small creature that looks like a stick got together with a sea horse.

Logan cuts the engine. Blanco and Steve Voss, a biologist who works in DMF’s Habitat Program, hop out and grab a cement block attached to a “fyke net” and place it on the boat. They then draw up part of the 100-foot net that resembles a kid’s play tunnel, big metal hoops separating chambers. The lengthy part of the net is anchored on the shore and goes straight down to the ocean floor.

“It is partly like a weir and partly like a seine,” says Logan, adding it can also be compared to the parlor of a lobster trap. “The flounder gets deeper and deeper until there is nowhere else to go.”

Blanco, a seasonal technician who is the muscle, spots a flat, grey mottled fish right away.

“A very surprise ending,” says Logan with a smile.

The two get the algae-laden net on the boat and take out the catch, one big winter flounder alive and flipping, as well as a smaller deceased summer flounder, a dead menhaden, and close to 50 crabs, mostly spider crabs but blue crabs and a rock crab as well.

Since mid-January, the trio has been in Waquoit Bay to sample water at 13 different stations, hauling fyke nets at four. The project is part of a multi-year endeavor to see when and how winter flounder are using estuaries.

The state has protections to avoid disrupting spawning winter flounder that extend from January to May or February to June varying from the south side to the north side (Cape Cod Bay). Those blanket restrictions have wreaked havoc with dredging schedules across the peninsula, resulting in shoaling of harbors and inlets.

But are the regulations really protecting flounder? The state and the Fishermen’s Alliance partnered to try to quantify anecdotal evidence that there were few, if any, winter flounder inshore anymore. The last time the state studied winter flounder spawning was in the 1960s; some believe that flounder are now spawning in coastal waters, not estuaries.

“A lot has changed since we last took a look,” Logan said, including a big jump in nitrogen from many more septic systems loading the shore.

“There is not a one-size-fits-all answer to this idea of when and where winter flounder are using these estuaries,” Logan said. “I think this is going to be a tool that ultimately will allow us to have a lot more nuances in where and when we apply the time of year restrictions.”

The tool he was talking about is eDNA, or environmental DNA, and on a crisp, sunny April day, Logan and his crew were wrapping up one of the final weeks of the testing season.

Logan pictures it this way: Within a bucket of water are cast-offs of animal DNA, maybe a cormorant came by or a striped bass swam through chasing a silverside. These little trails can be detected in this eDNA.

“You have this entire food web captured in this bucket of water,” he said.  “It sounds a bit magical.”

Last year’s water excursions, which included three spots on the south side of the Cape and three spots on the north, scooped up more than 1,000 samples in twelve months. One thing that is clear is that flounder are indeed using the estuaries.

Logan had specific coordinates set in the boat’s GPS and at the sound of the “beep, beep, beep,” he would hold the boat in place while Blanco and Voss sprang into action.

Blanco would grab a weighted framed triangle — imagine a tee pee without animal hide — with a stoppered brown bottle set firmly in the center. He’d then lower the contraption to the bottom, pull the stopper, and the bottle would fill. Meanwhile, Voss at the head of the boat would be lowering down a testing meter, which took water quality measurements like salinity, pH, turbidity and dissolved oxygen.

Those measurements were recorded and Blanco would pull the bottle up, stopper it and push it deep into an ice-filled cooler that filled with bottles as the day went on. Between taking water samples and depth measurements (the bay is so shallow they often see clammers standing far offshore) the trio would talk about sights – a bald eagle, a dog joining a construction crew on a roof top — and joke around.

Blanco, whose mop of curly hair is reminiscent of Stranger Thing’s Finn Wolfhard, has had different jobs in the fisheries, serving as an observer collecting data on fishing boats at one point. His real obsession is sharks and he has a tattoo of one that extends the length of his inside forearm.

Logan, about to motor from the river out into Vineyard Sound, had another ink idea for Blanco:

“Get a flounder, that would be badass,” he deadpans.

As Logan goes through the inlet to Waquoit Bay (closely watched by two big does on Washburn Island) he explains that there is only one way in and out for fish, and boats. Dredging to keep that way open is problematic because flounder lay eggs on the bottom and turbidity from the dredge extends beyond the channel and eggs can be suffocated. The eggs hatch in early spring and mini-flounder appear. They are round like other fish, as they grow older they become like pancakes, earning their flat fish tag.

The eDNA work done last year in six embayments showed that flounder were present in the estuaries to varying degrees, with two flounder “bumps” – one in late January, February into March when adults spawn and the other around July with a baby boom. These have been plotted and match expected peaks.

“There was a pretty clear switch between flounder being here, and flounder gone. It was a knife’s edge,” Logan said.

This year’s work at Waquoit using the fyke net aimed to see if hits the eDNA was picking up could be spawning flounder. The water samples taken this year and last year were collected each day and sent to the Division of Marine Fisheries office in New Bedford. Landing near the Waquoit Bay National Estuarine Research Reserve, Blanco lugged two coolers full of samples to shore, where Amanda Davis, the fourth member of the team, grabbed them and zipped away in her car.

Each bottle is filtered, and the material left behind is frozen and sent to the Gloucester Marine Genomics Institute (GMGI). Researchers ascertain what DNA is present.

Logan prefers the blend of the “old school” fyke nets and the new technology. During the first few months of the project they were getting steady amounts of winter flounder, many filled with eggs and clearly spawning.

“It was definitely like real fishing, we were very excited,” Logan said.

They would collect information and then return the flounder to the water, with Logan tagging them if they were big enough.

By establishing a link between eDNA and spawning adults in embayments, the state hopes to give towns the ability to test for flounder on their own. That is why they are testing bottom and surface waters; if the information links up, town staff may only have to sample at the surface.

“Simplicity is the goal,” he said.

Logan’s team is hopeful they will be able to do further research. They did notice variation between the six estuaries they studied, and that may play a role in what spots are dredged and when, perhaps lessen the time crunch communities are under.

For instance, the flounder pulse in Sesuit Harbor on the northside of Dennis started in March and stayed high through September, while Wellfleet Harbor had only one spate of detections in March, “pretty quiet from an eDNA standpoint.”

“We have a vision, but before we get to primetime, we have to understand the data,” Logan said.



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