Maine oyster-farming firms North Haven Oyster Company and Deer Isle Oyster Company are pioneering a plastic-free approach to oyster farming by testing alternative gear, and have successfully made it through their first season without using plastic.
In Maine, oysters are generally farmed from spring through fall, though there are some operations that operate year-round in areas that don’t typically freeze.
Oyster farming is widely considered more environmentally friendly than other forms of aquaculture, as it requires no freshwater input, produces negligible greenhouse gases, and provides ecosystem benefits like water filtration and carbon sequestration.
However, most farms rely heavily on plastic gear.
The two Maine farms use an off-bottom culture method, growing the oysters in floating cages, racks, or bags instead of on the seafloor. This method has historically depended on vinyl-coated trap wire, plastic mesh bags, and large plastic pontoon floats.
North Haven Oyster Company, located in North Haven, Maine, recently completed its first full season in 2024 using the method with plastic-free gear.
In place of plastic mesh bags, the company implemented cedar crates made from local native timber. According to North Haven Owner Adam Campbell, the firm’s oysters grew bigger in less time, and mortality rates dropped off to zero with the new gear, compared to the typical 10 percent annual loss.
“We had zero mortality on that oyster seed this summer, and this was the first year we're 100 percent plastic free. I've never seen that before. In the plastic bags, you always had morality. I believe it is the off-gassing of the plastic that's killing the baby oysters,” Campbell said.
Campbell further explained that the off-gassing theory comes from his time as a commercial lobsterman, when he once attempted to swap from wooden crates to plastic ones – only to find a dead lobster in every single crate after that first swap.
Later, Campbell spoke with someone in the plastics industry who told him the issue was due to off-gassing, which is when new plastic releases volatile organic compounds (VOCs), a process that continues indefinitely as the plastic breaks down. Campbell suspects the oysters kept in plastic mesh bags were also exposed to these VOCs, which may weaken them and contribute to higher mortality rates.
“What motivates me is that I live on this estuary; this water is in front of my house, and there's never been any industry here. I've always hated plastic, always been an environmentalist, and we know about plastics being endocrine disruptors,” Campbell said. “It’s also bad business with 10 percent mortality over 25 years, since I’ve been going. That's a lot of oysters, and it's just a dumb idea.”
On the flip side, a common industry concern with biodegradable alternatives to plastics is durability.
According to Campbell, this is something they plan to track with the use of the crates. As a testament to the durability of cedar, Campbell said he still has cedar buoys from the 1930s and ‘40s that have been exposed to the elements for over 80 years and remain in working condition.
Another advantage of cedar crates, according to Campbell, is their reparability. If a slat on a cedar crate breaks, it can be easily repaired with a hammer and a new piece of wood, extending its lifespan even further, he said.
“I'm not seeing any minuses right now, except that the cedar crates are more expensive than a [plastic mesh bag]. If you build them yourself, you could actually be really competitive,” Campbell said.
Farther north in Deer Isle, Maine, the Deer Isle Oyster Company uses MycoBuoys, which are mycelium buoys made with hemp created by mycologist Susan Van Hook in 2011.
Deer Isle has also been testing multiple other options to go completely plastic-free, such as replacing vinyl-coated trap wire with aluminum wire, swapping plastic mesh bags for cedar box frames with basalt mesh or perforated aluminum, using linseed paint-coated cork and untreated MycoBouys for flotation, and employing natural rubber or hemp line for fasteners.
Some of that gear has shown to be permeable and has gotten water-logged, according to Deer Isle, which said that further testing is needed to perfect the practice.
While many of the innovations require further testing, both farms remain committed to refining their plastic-free systems.
Deer Isle Oyster Company is listening to feedback from partner farms and continuing to collect data on oyster growth rates to improve their designs. North Haven Oyster Company plans to keep using cedar crates, test biodegradable buoys, and explore a modified version of the SEAPA oyster basket system, which is traditionally made of plastic but is being reimagined with cedar.
