Farming Seaweed And Shellfish Can Help Water Quality And Wild Fish Stocks, Report Finds

Unemployed Construction Workers Resort To Illegal Fishing — AYAMONTE, SPAIN - JUNE 26: Jairos places fresh coquinas (clams) in a basket held by his father Sebastian in their garage on June 26, 2013 in Ayamonte, Spain. On the black market one kilo of coquinas (clams) costs five euros, the average income for a day-shellfishing illegally is five euros (approx seven kilos). Before the recession the average salary was 2,500 euros per month for one of these constructors, now with illegal shellfishing they barely receive an average of 700 euros per month. Shellfishing in Ayamonte was banned on June 26, because toxins were detected in an area by autonomous authorities, who multiply fines by 10 for an illegal fisherman, going up from 300 to 3,000 euros. Ayamonte is a small fishing town of 20,968 people on the border with Portugal. It was one of the most popular locations for development during the Spanish real estate boom, due to its location. According to Ayamonte City Council, the unemployment rate has increased by 119.24 percent in the town following the loss of construction jobs which peaked in 2008. Hundreds of unemployed ex-construction workers try to earn a living fishing, despite the severe restrictions imposed by Junta de Andalucia, an autonomous authority which has a tight control over the fishing licenses in the town.

Heather Goldstone is the science editor at WCAI, the Cape and Islands NPR Station. She holds a Ph.D. in ocean science from M.I.T. and Woods Hole Oceanographic Institution, and spent a decade as an active researcher before leaving the lab to become a writer.

October 22, 2019

Updated July 03, 2023

Aquaculture is currently the third-most lucrative fishery in New England, after lobster and scallops. Oysters, and increasingly, kelp, are two of the most commonly grown foods.

Now, a new study says aquaculture could also be an important way to address issues like nutrient pollution and habitat loss. The study found that New England’s waters are among the top 20 locations in the world with the greatest opportunities for restorative aquaculture.

Aquaculture hasn’t been associated with environmental benefits, historically — in fact, it’s much more commonly known for pollution, when too many fish are crowded into coastal waters.

But it turns out that shellfish and seaweed, farmed properly, can dramatically improve water quality.

“Shellfish and seaweeds are at the bottom of the food web and they're able to actually take up nutrients from the water column,” said Seth Theuerkauf, aquaculture scientist with The Nature Conservancy and lead author of that global assessment.

Seaweed can also restore the proper pH balance of the ocean, Theuerkauf said. Ocean acidification is caused by excess carbon dioxide in the air, which forms carbonic acid in the ocean. Seaweed uses carbon dioxide to grow, causing the water nearby to become less acidic.

“We're beginning to get a sense that seaweed farms could be able to provide some localized benefits in terms of reducing the impacts of ocean acidification,” Theuerkauf said.

Shellfish grow better in less acidic waters, so there may be a benefit to growing shellfish and seaweed in the same area.

Another surprising benefit emerging from shellfish and seaweed aquaculture is the restoration of nearby wild ocean habitat, Theuerkauf said. In addition to taking excess nitrogen out of the water, shellfish aquaculture gear like cages, baskets and bags allow juvenile fish take refuge from predators, he explained.

What makes New England a great area for aquaculture?

Theuerkauf’s report incorporated factors around governance, food security, wastewater treatment and other things to arrive at the best places to grow more shellfish and seaweed.

The report sought to describe the places where aquaculture would provide the greatest environmental benefit, “but also social benefit, as well,” he said.