The content in this article draws much of its information from a 11/16/24 Erik Vance article: "Are Shellfish Good for You?" in the New York Times
With the new year fast approaching, annual resolutions to eat healthy foods will be a focus of many looking to improve their health. According to experts at Harvard's T.H. Chan School of Public Health, mussels, oysters, clams and scallops, (with mussels being most nutritious, closely followed by oysters) are some of the most nutrient dense animals on the planet, just behind small fish like sardines and anchovies. Lobsters and crabs are also in the shellfish category but are much less nutritious.(1)
Seafood is promoted as the gold-standard of animal proteins, yet there always seems to be a "yes, but"when it comes to seafood. "Yes, tuna is delicious and offers high-quality protein, but there are heavy metals in tuna. Yes, salmon is good for you and is high in healthy omegas, but salmon aquaculture is harsh on the animals and the environment. Yes, shrimp is good for you, but the mortality of the bycatch is a bummer. So, in this short list of examples, we can call out three consumer-concerns with seafood:
Biomagnification is a form of bioaccumulation where increased concentrations of toxins are found in species high on the food chain and are greater than the arithmetical sum of the amounts absorbed from organisms lower in the food chain. An example is the increasing concentration of fat-soluble compounds, such as PCBs, DDT, and mercury, in the livers of plankton, fish, fish-eating birds, and animals.
Most fin-fish aquaculture is harsh on the environment. Consumers are often "caught" between the less detrimental of two decisions: Wild or Farm raised? Given all of the information, neither choice seems without consequence.
Harvesting wild seafood on massive scales is both highly selective and indiscriminate. For example, the dolphin bycatch from tuna harvesting led to efforts to offer "dolphin-safe" tuna for consumers. And of local interest, many believe that the over-fishing of menhaden has led to the collapse of the stripped bass fishery in recent years.
The Good News:
Because oysters filter-feed algae at the bottom of the food chain, biomagnification is not a factor as it is with fin-fish. Also, oysters aquaculture is different than fin-fish farm aquaculture. Fin-fish aquaculture is done in tanks on land, or in the environment using large net-like enclosures. In either case, fin-fish are so densely packed into these enclosures that they require a lot of food to keep the fish alive until they are large enough to be sold. The resulting animal waste from these operations create concentrated nitrogen-heavy by-products contributing to algae blooms and oxygen deprived dead zones.
Conversely, oyster aquaculture involves no additional feeding. Oysters kept in enclosures are filtering the same water that their wild brethren filter for food. Along with eating the naturally occurring algae in the water, they also remove other suspended material in the water helping to improve overall water quality. In short, oysters do the exact opposite of fin-fish aquaculture - improving water quality vs. making it worse.
Moreover, with oyster aquaculture expanding to meet a growing consumer demand, it simultaneously takes harvest pressure off of wild oyster populations, letting native oysters to thrive. Add to this benefit, non-profit efforts such as the Billion Oyster Project in New York City, 10 Billion for the Bay by the Cheasapeake Oyster Alliance or the local sanctuary reefs installed by Lynnhaven River Now, and wild oyster habitats have a chance to rebound. As a keystone species for coastal ecosystems, and a fundamental component to shoreline preservation, a growing oyster aquaculture industry combined with the oyster recovery efforts like those mentioned here, provides a tremendous positive impact for our waterways and coastlines.
Yes, but,
After explaining how oysters filter feed and benefit the environment and water quality as a result, many wonder, "but doesn't that mean we are now eating the bad stuff the oysters filtered out of the environment?" We know our environment contains toxins, micro-plastics and the like. "How can oysters be healthy when they are taking in all of that when they feed?"
In the interest of public health, shellfish are one of the most highly regulated food sources. Water quality monitoring focuses on bacteria contamination to ensure low-risk harvest zones and the industry is closely regulated by government agencies so that the entire supply chain lowers food-safety risks for consumers. See this article for more on this topic.
In addition to these human interventions, oyster are highly selective "assimilators" meaning they not only filter water, but also differentiate what they eat (algae) from things that just might be suspended in the water (like suspended sediments) and discard items they can't actually use for food. They also have a toxicity detection super-power. Upon sensing something harmful in the water, they immediately shut down filtering and go dormant for a time. While scientists have found that many filter feeders take in microplastics, it is not clear if this poses a hazard to humans. This is particularly true for oysters. Oysters perform a secondary filtration process which discard what they can't use as food by binding it in mucous called pseudofeces (meaning false feces). This material is spit it out prior to any of this material entering the digestive tract.
Conclusion:
Oysters have offered humans high-quality protein throughout both our primitive and civilized histories. Their environmental benefits and nutritional value make them an excellent alternative for everyone. Interestingly, since oysters lack brains, they are now considered the only animal protein available to vegans. Now, the only decision to make is how you prefer to enjoy them: raw, baked, steamed, stewed, grilled, or smoked. LOC members can log in to their member area and explore the kitchen for recipes.
If you have any follow up questions to the information above or in general, please reach out to us. Note to readers: Some links above are not available to non-members. Members, if you are not already logged-in, you will be prompted to access members-only content.
Comments