Adams is harvesting today with her business partner Eric Oransky, who works fast, pulling up oyster bags and tossing them onto the deck. Dumping the contents onto a processing table, they count the oysters in groups of 10, occasionally knocking two together to make sure they’re alive. Then, Oransky sends each group of 10 through a chute and Adams catches them in mesh bags. Voila! They’re ready for delivery fresh off the boat.

These mesh bags aren’t made from ordinary polypropylene mesh, however. They’re woven out of string made with 100-percent European beechwood, which is sustainably harvested by thinning forests certified by the Forest Stewardship Council or the Programme for the Endorsement of Forest Certification. They’re the only plastic-free, biodegradable, home-compostable oyster “harvest” bags on the market.

Maine Ocean Farms uses roughly 1,200 of these bags every season. The bagging material is sold by Ocean Farms Supply, a business launched last year by Maine Ocean Farms and helmed by Adams. And although the company sells the material to oyster, clam, and mussel growers and wholesale distributors as far away as Mexico, California, and Florida, most of its business is local.

Already, the company’s bags have replaced the use of 14 linear miles of polypropylene mesh, according to Adams, who adds: “We are just beginning.”

Demand for non-plastic aquaculture gear is growing, as evidenced by the hundred or so seafood farmers who packed into a session at the Northeast Aquaculture Conference in April to hear Adams and others speak on the topic.

Aquaculture both contributes to and is potentially harmed by the ocean plastics crisis. Much of the industry’s gear, from ropes to cages to flotation devices, are made of plastic. Over time, that plastic degrades, generating millimeter-sized particles that can be ingested by shellfish and finfish, potentially harming their health. While harvest bags are a small part of the plastics used on a typical oyster farm—and in aquaculture more broadly—replacing them with a non-plastic biodegradable material is a step in the right direction.

They’re just one in a growing number of emerging innovations that mariculturists—small-scale shellfish and kelp growers—are developing to reduce their contribution to the ocean plastics crisis. Other new products include kelp-based ropes and lobster bait bags, oyster cages made solely from wood and metal, and cotton and hemp-based systems for growing shellfish larvae. While innovators are still grappling with longevity, durability, and the cost-competitiveness of new materials, the trend shows some promise.

“If you can create a biodegradable material, or something that’s more benign [for farming shellfish], then you’re improving the health of your product, the quality of your product, and the environment at the same time. It’s a win-win-win,” said Joel Baziuk, associate director, Global Ghost Gear Initiative, at the Ocean Conservancy.

Ocean Plastics and Aquaculture

Aquaculture contributes to ocean plastic pollution in three main ways, Baziuk told Civil Eats. Gear is lost from open water cages, wave action and extreme weather abrade plastic ropes, nets, and flotation systems, and single-use plastics used during routine operations can enter the ocean, particularly in regions with poor waste management systems.

“We know that [aquaculture] is a major vector, we just don’t know exactly how much, because there’s not enough research,” said Baziuk.

Some 1,300 marine animal species have been found to ingest ocean plastics, said Baechler. Bivalves filter enormous volumes of water to feed, which means that microplastics can get trapped in their gills or guts and cause blockages. Studies show that microplastics can decrease the ability of clams, oysters, and mussels to create energy; they can hinder muscle function and impair reproduction and growth. Hormone-disrupting chemicals like bisphenols and phthalates, which leach from microplastics, can also change marine animals’ behavior or affect their ability to grow, reproduce, and feed effectively.

Little is known about the impacts to humans who consume shellfish contaminated with microfiber, and more research is needed. But that doesn’t mean people shouldn’t consume shellfish, Baechler says. “It’s not a great thing for human health that we’re consuming microplastics, but it’s not a problem that’s specific to shellfish or seafood. It’s across the human food system.”

Pandemic-Inspired Innovation

Like many in Maine’s mariculturist community, Oransky is young, innovative, and environmentally minded. “Those are the people who are driving the interest in reducing plastics and coming up with non-fossil fuel-based technologies,” Sebastian Belle, executive director of the Maine Aquaculture Association, told Civil Eats.

Oransky searched far and wide for an alternative to plastic bags already on the market, testing bioplastics made from corn, soy, and other materials before turning to the beechwood bags made by an Austrian company, Packnatur. Then it took months of trials to perfect the bag for shellfish, because Packnatur’s original bags were designed for fruit and vegetables, not heavy, sharp objects like oysters.

When the pandemic hit and oyster sales tanked, Oransky decided to pivot and make the bag project about “more than just us.” He tapped Adams to lead the effort and Ocean Farms Supply.

“People told us they’d been looking for 15 years,” for a non-plastic packaging material, Oransky said. “It’s amazing that a few mariners, woodworkers, and shipbuilders figured it out.”

The bag material is manufactured in Austria because it’s cheaper to produce there, but Adams has begun conversations with the University of Maine to explore producing them locally. “It just depends on getting that [tree] species that would be suitable for growth here,” she said. The tree also couldn’t compete with what’s used by the timber and pulp industry.

For now, Adams said they’re focused on building the market. “Let’s get the product in use, let’s drop this plastic waste stream, and then take the next step and keep an eye on the future.”

Replacing Plastic Grow-Out Cages

The cages may also be a source of microplastics ingested by the shellfish growing inside them. There’s scant research on the issue, but one study found that exposure to microplastics from the aquaculture grow-out materials induced lower settlement success for oyster larvae and delays in growth.

Abby Barrows, an ocean plastics researcher and oyster farmer, is on a mission to replace this plastic. She’s developing experimental oyster bags made of cork and cedar trees, with fine stainless-steel or aluminum mesh on their tops and bottom. She’s also developing ropes made from Manila hemp.

“Oysters are touted as the most sustainable fishery, which I do believe [to be true], but we need to look at how we’re cultivating oysters and how we can further make it a sustainable system,” she told Civil Eats.

This summer, Barrows is running side-by-side experiments at a few farms, including her own, Long Cove Sea Farm, to compare how well baby oysters develop in wood and metal cages versus plastic ones. She’s collaborating with scientists in Nova Scotia, who will measure the microplastic content in the oysters.

“Ironically, we’re going full circle back to some of the gear that we first originally used,” Belle said. “Thirty-five to 40 years ago, our oyster growers were using bags made of wood and wire mesh.”

Developing an Alternative Sustainable Supply Chain

Getting that balance between longevity and biodegradability right for a non-plastic material is one reason why most efforts, other than Barrows’, focus on replacing single use plastics like harvest or bait bags. It’s easier to develop a truly biodegradable product that doesn’t need to be used for a long time.

For example, Katie Weiler, whose startup Viable Gear makes kelp-based aquaculture gear, wanted to tackle the mussel socks used to grow baby mussels before they’re big enough to attach to a line, but the product needed to last more than year. She decided instead to prototype kelp-based seeding twine to replace the nylon that kelp growers currently use. The twine needs to last five months to give the kelp plants enough time to establish on long lines in the ocean, said Weiler.

Weiler is also working on bait bags for the lobster and crab industries and is interested in kelp-based cling wrap to replace the plastic used to wrap boats in the winter. For now, her startup is targeting plastic items used in aquaculture that are easier to replace, she told Civil Eats. “Eventually, if we could come up with something more durable that doesn’t shed toxic microplastics in shellfish, that would be lovely.”

Cost is another big concern. Ocean Farm Supply’s bags cost 20 cents more per bag but they “communicate to customers that the oyster farmer cares about sustainability,” Oransky said. “Ten years ago, it would have been a hard sell,” he adds, but today, customer demands are shifting.

It’s too early for Barrows to know how much her wood and metal cages will cost, but she’s hoping to make them cost-competitive, partially through longevity. They’ll be designed to last 20 to 30 years, longer than their plastic counterparts, so they’ll be “an asset for your farm,” she said.

These efforts are just the beginning of solving aquaculture’s contribution to the plastic crisis. “Every step in the right direction is a step worth taking,” Baziuk said, “even if it’s not going to solve the problem overnight.”