Is Silver Salmon High in Mercury? A Comprehensive Look

According to U.S. Food and Drug Administration data, fresh and frozen salmon has an average mercury concentration of just 0.022 parts per million (ppm). So, is silver salmon high in mercury? Thankfully, this species, also known as coho salmon, is considered a 'Best Choice' for low-mercury consumption.

Quick Summary

Silver salmon, or coho, is a species of fish that is notably low in mercury. Its shorter lifespan and position lower on the food chain prevent the accumulation of high mercury levels, making it a healthy option for regular consumption.

Key Points

• Low Mercury: Silver salmon (coho) has consistently low mercury levels, placing it on the FDA's 'Best Choices' list for safe seafood consumption.

• Food Chain Position: Due to its lower trophic level and shorter lifespan, salmon does not accumulate high levels of mercury like larger, predatory fish do.

• Benefits Outweigh Risks: Health experts confirm that for salmon, the nutritional benefits, especially omega-3 fatty acids, far outweigh any potential risk from its very low mercury content.

• Safe for Sensitive Groups: Because of its low mercury level, silver salmon is considered a safe choice for pregnant women, nursing mothers, and young children, who are more susceptible to mercury's effects.

• Wild vs. Farmed: Both wild-caught and farmed salmon are low in mercury. While there are some differences, both are considered safe and healthy options.

What is Silver Salmon (Coho)?

Silver salmon, more commonly known by its other name, coho salmon, is a species of anadromous fish native to the Pacific Ocean and its tributaries. Prized for its mild flavor and delicate texture, coho is a popular choice for home cooking and restaurants alike. As an anadromous species, it spends its early life in freshwater before migrating to the ocean and returning to freshwater to spawn. Its diet primarily consists of smaller fish, squid, and crustaceans. Understanding the coho's biology is key to understanding why its mercury levels differ so significantly from larger, predatory fish higher up the food chain.

Factors Influencing Mercury in Fish

Mercury is a naturally occurring element, but human activity, particularly the burning of fossil fuels, has increased its presence in our environment. When it enters water systems, it is converted into methylmercury, a potent neurotoxin that can be absorbed by marine life. The concentration of this toxin in fish depends on several key factors:

• Lifespan: Longer-lived fish have more time to accumulate mercury in their bodies.
• Diet: Predatory fish that eat other mercury-containing fish experience 'biomagnification,' where mercury levels increase with each step up the food chain.
• Trophic Level: This refers to an organism's position in the food web. Fish at lower trophic levels, like salmon, generally have less mercury.
• Environment: The specific waterway and its contamination levels can affect a fish's mercury concentration.

Why Salmon is a Low-Mercury Choice

As a species, all salmon are considered low in mercury, and silver salmon is no exception. There are several reasons for this consistent low level, regardless of whether the salmon is wild or farmed:

1. Shorter Lifespan: Compared to large, long-lived predators like swordfish or shark, salmon have a relatively short life cycle, spending less time accumulating mercury.
2. Lower Trophic Level: Salmon primarily feed on small fish and zooplankton, placing them at a lower position on the marine food web. This contrasts with apex predators, whose mercury levels are magnified through their diet.
3. Growth Dilution (Farmed Salmon): Studies have found that farmed salmon can have even lower mercury concentrations than their wild counterparts. This is attributed to their controlled diet and rapid growth, which dilutes any mercury present.

Silver Salmon Mercury Levels vs. Other Fish

The table below compares the mercury levels of fresh/frozen salmon (including silver/coho) with other common seafood choices based on FDA data from 1990-2012. The figures demonstrate why salmon is considered a safe choice for regular consumption.

Fish Species	Mercury Concentration Mean (PPM)	FDA Advice Category	Potential Risk Factors
Salmon (Fresh/Frozen)	0.022	Best Choice	Low mercury level; safe for regular consumption.
Sardines	0.013	Best Choice	One of the lowest mercury levels.
Tuna (Canned, Light)	0.126	Best Choice	Lower mercury than albacore tuna.
Tuna (Canned, Albacore)	0.350	Good Choice	Higher mercury than light tuna; limit intake to 1 serving/week for sensitive populations.
Swordfish	0.995	Choices to Avoid	High mercury levels; should be avoided by sensitive populations.

How to Make Smart Seafood Choices

For consumers concerned about mercury, adopting a mindful approach to seafood consumption is prudent. Here are some simple guidelines:

• Vary your intake: Don't rely on a single type of seafood. By eating a variety of fish and shellfish from different sources, you can further minimize your exposure to any single contaminant.
• Prioritize low-mercury options: Focus on fish identified as 'Best Choices' by the FDA, which include salmon, cod, tilapia, and sardines.
• Check local advisories: For fish caught recreationally, consult local advisories from state or environmental agencies, as some local waterways may have specific contamination concerns.
• Balance risks and benefits: Health organizations worldwide emphasize that the nutritional benefits of consuming fish, such as omega-3 fatty acids, typically outweigh any risks associated with low-level mercury exposure.

Conclusion

To answer the question, is silver salmon high in mercury?, the resounding consensus from health and environmental agencies is no. Both wild-caught and farmed salmon consistently test with very low mercury concentrations, making them a safe and highly nutritious part of a balanced diet. Its shorter lifespan and lower position on the food chain naturally limit mercury bioaccumulation, a process that affects larger, longer-lived predatory fish much more significantly. Enjoying silver salmon as a regular protein source offers substantial health benefits, including vital omega-3 fatty acids, without the mercury concerns associated with other seafood species. For more detailed advice, consult the official FDA Advice on Eating Fish guidance.

Frequently Asked Questions

Is coho salmon high in mercury?

No, coho salmon, also known as silver salmon, is not high in mercury. It is officially listed by the FDA as a 'Best Choice' seafood option due to its very low mercury content.

What is the mercury level of salmon?

The average mercury level for fresh and frozen salmon is around 0.022 parts per million (ppm), which is considered very low and safe for frequent consumption.

Why is salmon low in mercury compared to other fish?

Salmon is low in mercury primarily because of its relatively short lifespan and its position lower on the food chain. This means it has less time to accumulate mercury through bioaccumulation than larger, predatory fish like swordfish.

Is it safe for pregnant women to eat silver salmon?

Yes, silver salmon is a safe choice for pregnant and nursing women. Health organizations recommend including low-mercury fish like salmon in the diet for its vital nutrients, like omega-3s, which support fetal development.

Does wild salmon have less mercury than farmed salmon?

Both wild and farmed salmon are low in mercury. Some studies even suggest farmed salmon may contain lower levels due to controlled feed and rapid growth, but both are considered safe options.

What are some fish high in mercury that should be avoided?

Some fish with high mercury levels to limit or avoid, especially for sensitive populations, include swordfish, shark, king mackerel, and bigeye tuna.

How often can I safely eat salmon due to mercury concerns?

Because of its low mercury content, salmon can be eaten frequently. The FDA and EPA list it as a 'Best Choice,' recommending 2-3 servings per week for optimal health.