The not so selfish shellfish

Shellfish may feel like a special occasion on a night out, but they play a regular part in the American diet. As of 2023, the average American eats 6.3 pounds of shellfish every year where 24% consume it regularly each week. From briny oysters to sweet crab legs, these foods have unique impacts on the environment, local economies, and your health. Understanding these impacts can help you make an informed choice about which shellfish, if any, fit best into your lifestyle.

In today’s issue:

• Early Adopters: Ecosystem engineers

• Health: Nutrients from the seafloor

• Environment: Shelling out pearls of wisdom

• Industry: Artisanal and wild

• History: A different kind of functional food

EARLY ADOPTERS

When it comes to shellfish, early adopters choose those enclosed by 2 shells. The best option from a health, industry and environment perspective are clams. Hard shell clams, common on the east coast, and manila clams, common on the west coast, are both powerhouses for nutrition, providing over 15% of the daily value for 11 micronutrients. Taylor Shellfish Farms, a fishery that takes an artisanal approach, is where early adopters prefer to buy their clams. They are the 1st US farm to achieve the Aquaculture Stewardship Council Standard for 7 shellfish including clams, oysters, and mussels.

Another great option are oysters. Compared to other indulgent shellfish, like lobster and crab, oysters have higher levels of Zinc, Omega-3 fats, Iron and B12 while also purifying water for their ecosystem.

If neither fit your lifestyle consider crab instead of shrimp, prawns, and crawfish. 95% of these species are farmed industrially taking much more water, land and emissions to replicate their natural habitat. In comparison, crab is much friendlier to your cholesterol levels and is primarily wild-caught from US and Canada based fisheries.

HEALTH

Nutrients from the seafloor

Shellfish have a rare combination of nutrients that deserves thoughtful consideration in your diet. Per serving, the most popular shellfish provide over 10% of the Daily Value for protein and omega-3s with little to no carbs. However, a shellfish allergy is the most common allergen affecting 2.9% of Americans, most often developing later in life between the ages of 30 and 50.

Shellfish are also rich in micronutrients and fit well into a nutrient-dense diet. Many popular shellfish contain more than 15% of the Daily Value per serving for 14 micronutrients, as shown in the table below:

Why can’t pregnant women have shellfish?

Pregnancy introduces a few additional considerations. Shellfish can accumulate mercury through biomagnification, with lobster having the highest levels at 0.1 ppm. While this may seem small, mercury exposure gets amplified for a developing fetus affecting brain development.

Even outside pregnancy, there are health nuances to consider, particularly when it comes to cholesterol. High levels of cholesterol are found in shrimp, prawns, crawfish, and calamari where excessive intake, especially from frequent large portions, can cause long-term health issues.

ENVIORNMENT

Shelling out pearls of wisdom

Not all shellfish are created equal, but quite a few have a phenomenal environmental footprint. While wild-caught shellfish need little to no water and land, farmed shellfish require large amounts of water in order to replicate their aquatic environments.

Here is how the resource needs compare to produce 1 pound of shellfish:

The most environmentally friendly shellfish are a subset called bivalve mollusks, made up of clams, oysters, mussels and scallops. They filter-feed for phytoplankton while also removing nitrogen, microplastics, and heavy metals from their ecosystem. This allows underwater plants to grow, providing nurseries for fish while working to prevent algae blooms and dead zones. Mollusks have another environmental benefit. The act as a living carbon sink by taking CO₂ from their environment in order to build a thicker shell.

INDUSTRY

Artisanal and wild

In 2024, the US produced 32% of the shellfish consumed in America. Coastal states, from Alaska to California on the west coast and Maine to Louisiana on the east coast, leverage their marine ecosystems to support production. To meet the remaining demand, the US relies on imports from 11 countries. The table below highlights just how heavily we rely on international trade partners to support current consumption levels:

In 2024, the US consumed 2.25 billion pounds of shellfish with shrimp accounting for 70% and crab 8%. For wild-caught shellfish, bycatch is a critical consideration. Bycatch refers to non-target species unintentionally captured during harvest, most of which are discarded dead or dying.

The below table sorts each shellfish species by its primary harvest method. Notably, claims, mussels, oysters, and octopus also have significant artisanal fisheries that contribute over 25% of annual harvest volume. This is significant because artisanal methods have a 10X smaller bycatch rate than industrial methods. Species that fall into this category are denoted by *:

To better understand how artisanal fisheries utilize environmentally friendly aquaculture practices, watch this video:

HISTORY

A different kind of functional food

Shellfish were one of the first protein sources for humans, found in caves in South Africa 160,000 years ago. From prehistoric foragers to Roman oyster farmers and Indigenous coastal cultures, shellfish played a critical role as reliable, nutrient-dense food that could be gathered with minimal tools. Their long relationship with humanity reflects not only dietary survival but also the development of trade, resource management, and an enduring connection between people and coastal environments that spans millennia.

Origins in Europe:

• Mussels - Denmark, 12000 BCE

• Octopus - Greece, 10000 BCE

• Calamari (Squid) - Greece, 10000 BCE

Origins in the Americas:

• Clams - US (Maryland), 5000 BCE

• Lobster - US (Maine), 4000 BCE

• Crab - US (Maryland), 3000 BCE

Origins in Asia:

• Shrimp - India, 2500 BCE

• Prawns - India, 2500 BCE

• Oysters - Japan, 2000 BCE

As demand grew and harvesting methods intensified, human reliance on shellfish increasingly turned into overexploitation. By the industrial age, once-vast oyster reefs and clam beds were heavily dredged, stripped, and in many regions effectively erased. Advances in transportation allowed shellfish to be shipped far from their source, transforming local food into global commodity and placing unprecedented pressure on coastal ecosystems. Pollution, habitat destruction, and unregulated harvest compounded the damage, leading to widespread population collapses by the 19th and early 20th centuries.

Compared to historic highs, by the late 1900s nearly all shellfish populations have been overexploited:

1. Oyster: 97% decline

2. Scallop: 97% decline

3. Shrimp: 93% decline

4. Lobster: 73% decline

5. Crab: 70% decline

6. Prawns: 60% decline

7. Clams: 45% decline

8. Octopus: 40% decline

9. Mussels: 25% decline

10. Calamari: 25% decline

11. Crawfish: 20% decline

Throughout history, shellfish have been valued for far more than their role as food. Their shells were fashioned into tools, utensils, and building materials, while crushed shells were used to make lime, pigments, and mortar for construction. Pearls and mother-of-pearl from oysters became symbols of wealth and power, incorporated into jewelry, religious objects, and ceremonial dress across many cultures. In some regions, shells functioned as currency or trade goods, linking coastal communities to inland economies. Shellfish were also used in traditional medicine and ritual practices, reflecting how deeply these organisms were woven into human technology, culture, and commerce long before modern industry emerged.

TIGHT 5

• 27K+: the number of shellfish species worldwide.

• 400 Million: years ago, there were fossil evidence of clams, long before dinosaurs.

• 50 Gallons: of water is filtered every day by just 1 oyster.

• Swimming: is possible when scallops rapidly open and close their shells.

• 400: US-based Mussel Watch programs monitor water contaminant trends.

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