Are Mussels, Clams and Oysters the Most Ethical Seafood?

Bowl of clam tapas with a lemon wedge on top

Quinn Dombrowski / Flickr / CC BY-SA 2.0

One scientist believes that these plant-like bivalves could build much-needed food security in aquaculture.

The next time you’re craving seafood, a steaming bowl of clam chowder or a dish of garlic-steamed mussels could be your best option. Not only are they delicious and nutritious, but they’re also a more environmentally friendly choice than fish and crustaceans.

Clams, mussels, and oysters are bivalves and members of the invertebrate mollusk family. They differ from other mollusks, such as octopus, for their evolutionary simplicity. Bivalves are sessile (immobile) and plant-like in the way they filter nutrients from the water around them and do not require feeding. They develop a meaty edible muscle that is rich in omega-3s, without the mercury levels found in larger fish.

In an article for Solutions journal, scientist Jennifer Jacquet makes a convincing argument for bivalves being the most ethical choice for seafood farming. She believes the world is at an important junction right now, with aquaculture exploding worldwide, but rapidly becoming a water-based equivalent to our horrific land-based animal agriculture industry. Now is the time to reassess and come up with a better strategy for seafood, before it gets any worse.

Bivalves are the answer, in Jacquet’s opinion, and here’s why:

1. Bivalves don’t require feeding.

As mentioned above, bivalves filter their nutrients from the water, cleaning anywhere from 30 to 50 gallons of water per day, which improves the habitat for other fish around them.

What many people don’t realize about farmed finfish and shrimp is that they need to eat other smaller fish in order to grow. Aquaculture means that more wild fish must be caught in order to feed the farmed fish.

This ‘fishmeal’ comes from krill, anchovies, and sardines, and is purchased cheaply from developing nations like Peru. It has a negative effect on the seabirds, marine mammals, and larger finfish that are now competing with aquaculture for their food supply, and on local populations who would normally eat these small fish.

2. Bivalves build food security.

Because bivalves do not require feeding, this frees up wild-caught fish to feed local communities, while providing nourishment themselves.

In a world that is increasingly food-insecure, it makes no sense to be purchasing fish from poor nations in order to feed fish, like British Columbia-farmed salmon, that is sold exclusively to luxury markets. In fact, the practice goes against the UN Food and Agriculture Organization’s Code of Conduct for Responsible Fisheries, which advises capture fisheries

“To promote the contribution of fisheries to food security and food quality, giving priority to the nutritional needs of local communities.”

3. Welfare is not as serious a concern.

The effects of farming would be considerably less for bivalves than other farmed fish, as they do not require space or enrichment in order to grow, nor do they migrate like salmon. One could argue that bivalves are plant-like. This does not mean there are no welfare concerns, but their life in captivity would not be all that different than in the wild.

Jacquet describes the ideal species for aquaculture:

“It should be a species group that does not require fish feed, does not require conversion of habitat, does not contribute to pollution, and has very little potential to be invasive. It should consist of animals who are not likely to experience significant pain and suffering in captivity in particular—animals whose health and wellbeing is at least somewhat compatible with industrial methods.”

There was a time when bivalves made up more the aquaculture industry, around 50 percent in the 1980s, but now that number has dropped to 30 percent, due to popularity of finfish. Jacquet wants to see that number rise again, as it would signify a shift in a more sustainable, humane, and secure future.

It’s not a perfect solution, though, as shown in a short film called “A Plastic Tide,” which revealed mussels absorbing plastic micro-particles from seawater – the distasteful side effect of rampant plastic pollution. But, then again, this problem affects all sea creatures, not just bivalves.

Jacquet makes a solid argument, and one that I’ll certainly consider the next time I’m standing in front of the fish counter. I hope you do, too.