What's An Upweller?

By: Tim Wood

Topics: Commercial fishing and shellfishing , Shellfishing

Millions of tiny quahog seed are grown out every year in the upwelling system. FILE PHOTO

Constable Gives Primer On Shellfish Grow-out System

by Tim Wood

CHATHAM – A recent proposal to construct a new shellfish upweller on Stage Harbor raised an important question: Just what is an upweller?

“I had folks who came up or called and wanted to know what's an upweller,” said Selectman Jeffrey Dykens. “Some of my mother's friends were saying 'What the heck's an upweller?'”

At Dykens' request, Shellfish Constable Rene Gagne answered that question last week in a presentation she dubbed “Upweller 101.”

 

So what exactly is an upweller?

Simply put, the primary purpose of an upweller is to grow shellfish, said Gagne. The town's upweller, located in the ground floor of the harbormaster's building at Old Mill Boatyard, grows mostly quahogs, but is also used to nurture oysters and bay scallops.

The facility includes three upper and three lower tanks that hold water pumped in through an intake in Stage Harbor. Seed shellfish are placed in silos that sit in the tanks. The shellfish are placed on top of a fine mesh.

“We try not to put it too thick because if you do that the animals in the middle won't get food,” Gagne said.

Water circulating through the system comes up through the mesh. “That's why it's called upwelling,” she said. Three pumps under the float dock at Old Mill Boatyard keep the water circulating. Water is funneled through the tanks and into troughs, and then is pumped back out in the harbor.

It's important to point out that an upweller is not a hatchery. A hatchery, like Aquaculture Resource Corporation facilities in Dennis, nurtures shellfish larvae in vats that require very specific temperature and nutrient controls, growing them out to seed. “Their mission is different; they grow seed to sell,” Gagne said.

 

How does it work?

Nutrients in the water circulating through the upweller provide food for the baby shellfish, which start out at two to three millimeters. In this safe and nurturing environment, free from predators, the seed grows rapidly.

“The best growth rate are the animals that are able to stay in that upwelling system for the longest period of time,” Gagne said. “But eventually we don't have enough room.” The shellfish are kept in the upweller as long as possible, thinned out as they grow so that they don't smother each other. Eventually, when they are about 11 to 16 millimeters, the growing quahogs must be moved out. They're planted under nets in grow-out areas in Mill Creek to protect them from predation by crabs and moon snails. About 150,000 quahogs are placed under each net.

“But then we have to go back and dig those out.” It can take two to three years for the quahog to grow to 25 millimeters, about the size of a quarter.

“That's sort of the industry standard where shellfish are able to live on their own out in the natural environment. They're less susceptible to predation because their shells are thicker, they're bigger, so some of our predators like green grab can't get their claws around the shellfish.”

At that point the shellfish are distributed throughout the town's coastal waters. Between the 25 millimeter size and when quahogs are legal to harvest – when the shell is one inch thick – they become sexually mature and spawn several times, helping to naturally propagate the wild shellfishery.

 

What's the benefit?

“Chatham has the most valuable wild shellfishies within the state of Massachusetts,” exclusive of sea scallops and ocean quahogs, which are the “big boat New Bedford stuff,” Gagne said. In wholesale value, Chatham's annual commercial landings range from $2 to $6 million. Since only residents can qualify for a commercial shellfish permit, the industry directly supports the town's year-round economy. In 2017, 319 commercial permits were sold (including junior and senior permits). Some shellfishermen work in the industry full-time, others use it to supplement their income. There were also 2,512 recreational permits issued, but it's difficult to put a value on that, she said.

“What we know is that a lot of people who come here go shellfishing with their families. It's part of their experience here,” Gagne said. Many upweller-grown shellfish are distributed along the Morris Island causeway, one of the most popular recreational shellfish areas in town.

Both commercial and recreational permit fees support the propagation program, with 75 percent of commercial sales and 25 percent of recreational sales going into a revolving fund used to purchase seed. This year, $50,000 is budgeted for seed and maintenance of the upweller, all of it from the revolving fund.

Quahogs are the industry mainstay. The wild shellfishery tends to be cyclical, and some years there are few other species available. Quahogs “really are our insurance for years when nature just doesn't cooperate,” she said.

“The ultimate goal is to create a sustainable fishery,” Gagne said. Other fisheries are “constantly extracting.” Here, “we keep putting animals back.”

 

Why is an upweller needed?

Chatham has had a shellfish propagation program for more than 40 years, Gagne said. Former shellfish constable Kassie Abreu began experimenting with different grow-out methods when aquaculture-grown seed became easily available. At first state money was available to buy seed, but when those funds dried up officials concluded the town's best option was to build an upweller to grow out affordable seed.

It's still the least expensive way to support the town's wild shellfishery. Two to three millimeter seed costs $12 per thousand; the town buys about two million a year. To buy that volume at the size at which the shellfish are placed under nets would cost $35 per thousand, or $70,000 for two million. To buy quahogs at the 25 millimeter size would cost $120,000 for two million – if that many were available.

“When the hatchery asked how much we were looking and I said two million, they said no way,” Gagne said. It would be more lucrative for them to hold on to them a bit longer until they're legal size, when they can be sold for 25 cents each.

“Completely eliminating the upweller, we wouldn't be able to rely” on getting the same volume of shellfish from commercial aquaculture operations.

The upweller is also used in collaborations with education programs involving the Monomoy Regional Middle School, Mass. Audubon's summer program and the Stage Harbor Yacht Club.

“All of that is teaching people about the environment, about their backyard, and the benefits of shellfish, which are numerous,” Gagne said.

 

Why does the current upweller need to be replaced?

Retrofit into the space it now occupies, the present upweller not only can't be expanded, but it's showing its age.

“We are keeping that thing together with a lot of plumbing cement and some duct tape,” Gagne said. “In and of itself, it needs a revamp.” The pumps must run constantly, and when there power goes off they have to be manually reset as soon as possible. For years shellfish staff would “babysit” the system during storms. “If [the power] flickers, we have to turn it back on.” Now a camera trained on the system allows her to see if the power goes out.

The intake is also located at one of the most popular docks in town, which is where boaters get fuel and pump out marine toilets. People also use chemicals to wash down boats. If contamination gets sucked into the upweller, it could damage or kill the shellfish.

“The problem is we have no reaction time,” Gagne said, due to the proximity of these activities to the intake.

 

What's the plan to replace it?

Under a proposal presented to selectmen a few weeks ago, a new upweller would be built on the 90 Bridge St. property the town purchased a few years ago. It's advantage, Gagne said, is that it would continue to rely on the nutrient-rich waters of Stage Harbor and would be able 25 to 30 percent larger than the current facility, increasing capacity by about one third. The workspace would be larger, too; the current upweller has narrow isles staff has to squeeze down. There's also little opportunity for the public to view the system; a new facility would be more conducive to that. It would also share an emergency generator with the adjacent Mitchell River drawbridge, “so our investment stays healthy and safe,” Gagne said.

While there is a fueling station at the nearby marina, should there be a spill there would be more notice before the contamination got sucked into the upweller, Gagne said.

“That activity wouldn't be happening directly over the intake pump,” said is now the case, she said.

But the $4 million proposal, which also includes docks and piers, was too much for selectmen, who sent it back to the waterways-related committees who'd developed it for further revisions.

No one doubts the need for the upgraded upweller, however, especially after Gagne's comprehensive presentation last week.

“It's an integral part of this community, our economy,” said Dykens.