Fish is a valuable part of a balanced diet, offering essential nutrients such as omega-3 fatty acids. These healthy fats may help reduce the risk of various conditions, including heart disease, cancer, Alzheimer’s, dementia, vision loss from age-related macular degeneration, and rheumatoid arthritis [1]. However, not all fish are equally safe to consume.
Industrial processes—such as coal-based power generation, metal smelting, and waste incineration—have released significant amounts of mercury into water systems. This toxic metal enters the aquatic food chain, where it undergoes bioaccumulation. As smaller fish are eaten by larger predators, mercury concentrations increase at each step of the food chain [2]. Excessive mercury consumption can pose serious health risks, including mercury poisoning.
To help consumers make informed choices, the U.S. Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) have established safety guidelines for mercury intake. Additionally, the Environmental Defense Fund (EDF), a non-profit organization, provides recommendations on which fish to limit or avoid due to high mercury levels [2]. By selecting low-mercury options, you can enjoy the benefits of fish while minimizing potential risks.
Atlantic Cod
The issue with Atlantic cod isn’t primarily about health risks—it’s about the survival of the species and the balance of marine ecosystems. For centuries, Atlantic cod has been heavily fished, leading to a devastating population collapse in the late 1990s. Despite strict fishing restrictions since then, the species has failed to recover at the expected rate.
Scientists warn that this collapse has permanently altered the North Atlantic’s food web, disrupting predator-prey relationships and marine biodiversity. Today, Atlantic cod is classified as a vulnerable species, raising concerns about its long-term survival [3]. Choosing sustainable seafood alternatives can help reduce pressure on this struggling population and support ocean health.
Atlantic Flatfish (halibut, flounder, and sole)
The issue extends beyond just overfishing—it’s also about staggering levels of waste. Commercial fishing operations generate massive amounts of “bycatch,” the unintended capture of non-target marine species, which are often discarded dead or dying. In U.S. fisheries alone, an estimated 2 billion pounds of bycatch are thrown back into the ocean each year—enough to provide half a billion meals [4].
One of the biggest offenders is the California gillnet fishery, which targets halibut but ensnares countless other marine animals in the process. If you’ve eaten halibut in the U.S., there’s a good chance it came from this destructive fishery. This unsustainable practice not only depletes fish populations but also disrupts entire marine ecosystems. Choosing responsibly sourced seafood can help reduce the demand for such harmful fishing methods.
Caviar
Caviar, the prized eggs of the beluga sturgeon, comes from a prehistoric fish that can live up to a century. These luxurious eggs command staggering prices—sometimes thousands of dollars per pound—making them one of the world’s most expensive foods. But this demand has come at a devastating cost.
Due to relentless overharvesting, the beluga sturgeon is now critically endangered, teetering on the brink of extinction. Sadly, many other sturgeon species face the same fate, their populations decimated by the insatiable global appetite for caviar. Protecting these ancient fish requires urgent conservation efforts and responsible consumer choices.
Chilean Bass
This species faces a dual crisis—not only has it been pushed to the brink by decades of relentless overfishing, but it also carries dangerously high mercury levels, posing serious health risks to consumers [6]. The combination of ecological decline and toxic contamination makes it a prime example of unsustainable seafood. Choosing safer, more responsibly sourced alternatives can help protect both marine ecosystems and human health.
Eel
That tempting eel dish on the sushi menu comes with hidden costs. These slow-growing fish take years to mature, making them particularly vulnerable to overfishing. Many wild eel populations have already crashed under fishing pressure, with ripple effects across aquatic ecosystems. Eels play a crucial environmental role by helping distribute mussels – nature’s water purification system [7].
Beyond conservation concerns, eels pose health risks as “chemical sponges” of the waterways. Their bodies accumulate dangerous pollutants so effectively that some health agencies recommend limiting consumption to just once per year [8]. When craving sushi, consider more sustainable and safer alternatives to protect both your health and fragile eel populations.
Imported Basa, Swai, Tra, Striped Catfish
Beware of vaguely labeled “catfish” – what you’re getting may come with dangerous contaminants. A 2016 study revealed alarming findings: 70-80% of these fish tested positive for Vibrio bacteria, the primary culprit behind shellfish poisoning [9]. This common yet potentially harmful pathogen can cause serious foodborne illness, making these fish a risky choice for your table.
When shopping for seafood, look for clearly labeled, responsibly sourced options to ensure both your safety and the health of aquatic ecosystems. Your best bet? Choose suppliers who provide detailed information about their fish’s origin and handling practices.
Imported Farmed Shrimp
Global shrimp farming relies heavily on a cocktail of pesticides—nearly all of which are banned in the United States due to their toxicity. But the concerns don’t end there. To combat disease in overcrowded farms, producers often dose shrimp with excessive antibiotics, contributing to the rise of dangerous, drug-resistant bacteria.
Handling or consuming these shrimp—especially in raw or undercooked form—could expose you to antibiotic-resistant pathogens, posing serious health risks. When buying shrimp, opt for responsibly farmed or wild-caught varieties from trusted sources to minimize these dangers.
Imported King Crab
Most crab sold in American markets—about 75%—is actually imported from Russia, where overfishing and environmentally harmful fishing methods are widespread. By law, only crab harvested in Alaskan waters can legally be labeled as “Alaskan King Crab.” However, seafood mislabeling is a persistent issue, making it difficult for consumers to know what they’re really buying.
Red flags to watch for:
- Labels that say both “Alaskan” and “imported”—this is a clear contradiction
- Vague or missing origin information
To avoid supporting unsustainable fisheries:
✔ Look for trusted certifications (like MSC-certified)
✔ Ask retailers for transparency about sourcing
✔ When possible, choose verified Alaskan crab
Being an informed consumer helps protect both marine ecosystems and the integrity of sustainable fisheries.
Orange Roughy
Orange roughy face a perfect storm of threats that make them one of the most unsustainable seafood choices:
Critical Conservation Concerns
- Exceptionally slow-growing, taking 20+ years to reach breeding age
- Can live over 50 years, but populations can’t recover quickly from overfishing
- Decades of intensive harvesting have pushed stocks to dangerously low levels
Health Risks
- Known to accumulate high mercury levels in their flesh [7]
These biological factors – combined with contamination risks – make orange roughy a seafood selection that conscientious consumers should avoid entirely. Fishery managers worldwide have implemented strict catch limits, but the species’ future remains uncertain due to its extraordinarily slow reproductive cycle.
Shark
As apex predators, sharks face two critical challenges that make them particularly vulnerable:
1. Dangerous Mercury Accumulation
- Their position at the top of the marine food chain leads to extreme bioaccumulation of mercury [7]
- Mercury levels in many shark species exceed safe consumption limits
2. Reproductive Vulnerability
- Exceptionally slow growth rates, with some species taking decades to reach sexual maturity
- Low reproductive output makes population recovery nearly impossible under current fishing pressures
- Many species have suffered catastrophic population declines (up to 90% in some cases)
This combination of health risks and ecological fragility means shark products – including shark fin soup and shark steaks – represent one of the most unsustainable seafood choices available. Conservationists strongly recommend avoiding all shark products to protect both human health and these ecologically vital predators.
