Plastics and the future of seaweed aquaculture.

The growing seaweed aquaculture industry is based on the use of longlines. These longlines present numerous issues including the risk of entanglements to marine species and birds, hazards to navigation, the exclusion of other marine uses such as fishing and recreation, and notably the release of plastics into the marine environment.

Up to 90% of ocean-based source plastics is from fishing and aquaculture gear. These plastics pose an entanglement risk with an estimated 267 animal species suffering from entanglements and the ingestion of plastic debris.

Here in Maine for example, where lobstermen actively use more than 2 million traps, it’s estimated that 5 percent to 10 percent - 100,000 to 200,000 traps - are lost in any given year. These traps continue to entrap marine species and release plastics into the environment which can then be ingested by marine species and birds.

As seaweed farming expands it is likely that similar gear losses and environmental impacts can be expected. A current seaweed lease application for Casco Bay in Maine proposes to have over 12 miles of line in the water at best 7 feet under the water’s surface. This is a tremendous amount of line, not to mention the roughly 100 moorings that go from the sea floor to the surface and roughly a thousand surface buoys. Like lobster fishing, when this density of gear is deployed you are assured to have significant losses.

The seaweed industry must take steps to develop growing technologies that rely less on plastics (ropes/lines/buoys), utilize more of the water column, and minimize impacts to other marine uses. This should also include the use of biodegradable and non-toxic lines and substrates.

At Springtide Seaweed we are working to create aquaculture farm designs that minimize environmental impacts and use conflicts. These efforts include maximizing yields so less gear is needed per pound of seaweed grown, the use of growing modules that can be deployed at depths that permit marine traffic to pass over our farm site, as well as year round growing systems that permit higher production with smaller leases.

We are also using experimental substrates that are safe and biodegradable.

The MSE is available to support any growers that wish to explore new growing technologies that make seaweed aquaculture more sustainable. Feel free to reach out!

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