Oysters have a multitude of environmental benefits, but farming them presents problems.
Oysters have appeared consistently throughout historical records. Evidence of their consumption was found in South African caves from more than 160,000 years ago, and records also show they were enjoyed by wealthy ancient Romans and Greeks. In the 18th century, an increase in production caused prices to drop, and they became working-class dietary staples. Today, in the U.S., you can pick up a tub for around $13. But despite their rich history, should we still be eating oysters?
When oyster populations are left to thrive, oysters are climate heroes. But aquaculture — farming oysters in cramped, dirty man-made environments — can have a negative environmental impact. Plus, the jury is still out on whether bivalves can feel pain, bringing ethics into question.
Oyster farming: is it sustainable?
In the wild, oyster reefs are incredibly beneficial to the environment. They are an example of blue carbon, which means they are an ocean-dwelling species that can sequester carbon dioxide; they need carbon dioxide to grow their shells. (Other examples of blue carbon include whales, seagrass, and mangroves.)
Oysters also improve the overall health of the oceans by increasing water clarity and water quality, which helps other species to thrive. A healthy oyster reef can provide vital habitats for animals like shrimp, herrings, and crabs, but these reefs are in danger. Back in 2009, one report found that 85 percent of oyster reefs worldwide have disappeared, largely due to the world’s huge appetite for shellfish, which led to overharvesting.
But the global oyster market is still growing, and that’s due to an expanding aquaculture market. Oyster farming is often hailed for its sustainable credentials. Because, on farms, they still offer the ocean the same purifying benefits, and they can still sequester carbon. But there are some drawbacks. Increasing research suggests that these farms can cause environmental damage. One 2016 study, published in the Journal of Fisheries & Livestock Production, noted that oyster cultivation can contribute to environmental disturbances, like the removal of water nutrients and a reduction in seagrass, as oysters “compete with other organisms for survival.”
Another concern is that aquaculture may increase the presence of invasive, disease-spreading organisms and species, as well as take habitat away from animals that rely on it, like seabirds. The study, which calls for appropriate and clear environmental management and planning, notes: “The species most likely to be affected by loss of habitat are birds whose feeding and breeding habitats are suitable for oysters farming and which feed or breed on the low shore to mid-shore. This may increase their energy requirements, and hence adversely affect survival.”
Environmental issues aside, the farming of oysters is also associated with potential welfare implications. Right now, little is known about the sentience of bivalves, but some research suggests that their nervous systems do react to potential harm. This doesn’t necessarily mean they experience pain in the way that other animals do, but it does imply that they may have evolved to try and avoid the risk of damage. Jeff Sebo, a professor of environmental studies at New York University, told Sentient Media, it makes sense not to eat them if we don’t have to.
“We want to be encouraging people to frame animals as not to be eaten rather than get into the psychologically more complicated territory of labeling some animals as to be eaten, but other animals as not to be eaten,” Sebo said.
The solution? Wild oyster restoration
Out in the oceans wild oysters also need support. And that’s why projects, like the U.K.’s Wild Oysters Project, are focused on the restoration of oyster reefs. So far, the project has helped to release one billion oyster larvae, which has resulted in the filtering of 22 million liters of water.
It has also released a “how-to” guide, to help other communities and NGOs support oyster restoration. Its efforts are specifically focused on Europe, where the European flat oyster is nearly extinct because of habitat destruction and overfishing. But the initiative isn’t alone.
In the U.S., The Nature Conservancy has been rebuilding oyster reefs in the Great Bay Estuary in New Hampshire. And in Scotland, one WWF project aims to restore four hectares of seagrass meadows and reintroduce 30,000 oysters in the Firth of Forth.
Speaking about the project in 2022, which is being financed by the ScottishPower Fund, Ricardo Zanre, WWF’s ocean restoration program manager told The Scotsman that the decline of seagrass and oysters was a “concerning loss in so many ways.”
“For the homes they provide for marine life, their value in absorbing carbon dioxide and improving water quality, and their importance as a heritage for coastal communities,” he added. “The Forth is an amazing example of a place where local communities working to restore coastal habitats can not only help to bring back these benefits but also to strengthen the connection between nature and community.”
And if you’re looking to cut back on your oyster consumption, try a plant-based option like this recipe from Lauren Toyota’s Hot for Food.
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