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Making healthy and sustainable
seafood choices

by Thais Harris, NC
Nutrition Education Manager, Ceres Community Project
April 2016

At Ceres we provide a fish entree every week because we believe a balanced diet includes healthy, sustainable fish, as proven by the Mediterranean way of eating. According to the Mayo Clinic, “research has shown that the traditional Mediterranean diet reduces the risk of heart disease. In fact, an analysis of more than 1.5 million healthy adults demonstrated that following a Mediterranean diet was associated with a reduced risk of death from heart disease and cancer, as well as a reduced incidence of Parkinson's and Alzheimer's diseases.”(1) Aside from a large amount of vegetables, fruits, nuts & seeds, whole grains, and extra virgin olive oil, the Mediterranean Diet is also rich in healthy fish.

Fish are high in nutrients most people are lacking, such as the anti-inflammatory omega-3 fatty acid, iodine and other minerals, and vitamin D along with other important vitamins.

An analysis of 20 studies involving hundreds of thousands of participants showed that eating one to two 3-ounce servings of fatty fish a week—salmon, herring, mackerel, anchovies, or sardines—reduces the risk of dying from heart disease by 36 percent. (2)

Like many other foods, not all fish is created equal. There are health, environmental and economic considerations to be made, while keeping in mind that, with some exceptions, the benefits of eating fish far outweigh the risks.

Benefits of eating fish

• Rich source of protein, iron and iodine

• Provides B vitamins, including B-12

• Promotes normal fetal growth and child development

• Wild, oily fish are the richest source of omega-3 fatty acids, which has shown benefits in the prevention and treatment of:

· heart disease

· high blood pressure

· inflammation

· mental health disorders

· diabetes

· digestive disorders

· autoimmune disease

· cancer

Current dietary guidelines suggest that Americans should increase their seafood consumption by replacing some meat or poultry with seafood. A total intake of at least 8 ounces, up to 12 ounces per week (or more) of a variety of seafood is recommended. That means eating seafood 2 to 4 times a week.

When deciding to follow this guideline, we need to consider where the seafood comes from (local, national, overseas); how it was caught (sustainable methods that don’t harm other species or overfish); how it was raised (if farmed, what practices were used?); whether it was exposed to contaminants (top of the food chain fish can have high mercury levels, some lake and river fish can have high PCB levels); and whether it is high in the beneficial Omega-3 fatty acids.

Let’s take a deeper look into these issues to better understand which fish are the healthiest.

Wild/ Sustainable Fish

We choose wild and sustainable seafood because we believe it is the safest seafood we can offer, both for our clients and for the planet. The location and living conditions where fish and seafood live affects what they eat, their exposure to chemicals, and how much they move, dictating the state of their health and their nutritional profile. Samples of wild Pacific salmon tested at laboratories in British Columbia had eight times more Vitamin D and three times more Vitamin A than farmed Atlantic salmon. 

Unfortunately, even wild fish (namely the big fish on the top of the food chain, see list below) can be contaminated with chemicals or mercury, so please see the lists below to identify which species are safest. Overfishing is another concern when it comes to wild fish, and the lists below also identify what the best choices are when considering fishing practices and sustainability.

Farmed Fish: Good Practices and Types to Avoid

Farmed fish has been known to contain higher levels of contaminants, as well as having a negative impact on the environment; however, there are now many ethical farms that take good care of their fish and limit contaminant exposure, working with closed containment technology to avoid having a negative environmental impact. The only challenge is identifying which farmed fish comes from a “best-practices” farm, so please ask questions when buying farmed fish.

Closed System Aquaculture is a more sustainable and viable way to farm fish, currently used to raise species such as tilapia, trout and salmon in Canada, the US and China. This system can eliminate or significantly reduce water pollution from feed, feces and chemical waste and contamination of the seabed under farms; eliminate escapes from the rearing facility; eliminate marine mammal deaths (no interactions and no nets); eliminate or reduce the risk of disease and parasite transfer to wild salmon; and significantly reduce the need for antibiotics and chemical treatments in raising fish.

If a fish farm is not employing sustainable practices, it might be wise to limit consumption especially when we consider what the fish is fed in the farms, which is wildly different – no pun intended – than what they get in their natural habitats. Fish are not intended to eat grains, corn, soy, or pig meat, which are just some of the foods they are fed in most fish farms. Another concern is that farmed salmon is often fed synthetic astaxanthin (made from petrochemicals that are not approved for human consumption) to make their flesh the pink color people expect (unlike wild salmon, farmed salmon has a grayish color).

The Coastal Alliance for Aquaculture Reform (3) has published concerns with salmon farming, including:

• Environmental Impacts: sea lice from farms infecting young wild salmon; diseases such as Infectious Salmon Anaemia and Bacterial Kidney Disease occurring in farms usually call for application of vaccines and antibiotics which can pass into the surrounding environment; marine mammal deaths from open-net cages; marine debris such as lost fish farming equipment; algae blooms in surrounding environment from excessive nutrient loading in farms; escapes and alien species out-competing wild salmon for habitat and food and spreading disease and pathogens to wild fish; and concerns with the fish feed (foods not meant for seafood, antibiotics, synthetic agents).

• Human Health Impacts: PCB chemicals (see PCBs details below); excessive antibiotic use and resistance; and chemical exposure (from colorants to fungicides applied in fish farms).

The USDA’s dietary guidelines state that eating fish – even if it is farmed – offers more benefits than not eating it. Check out the Monterey Bay Aquarium’s Seafood Watch to find out which farmed fish is healthiest.

The Concern with Mercury

Mercury is a toxic heavy metal that can accumulate in fish. Eating fish with high levels of mercury can negatively impact brain development in children and can affect learning and memory function in adults. Certain fish species are known to have higher mercury concentrations than others, sometimes due to polluted waters. The highest levels of mercury and contaminants tend to accumulate in the large predatory fish at the top of the food chain (4).

The EPA (5) provides the following advice for women who are pregnant, planning to become pregnant or nursing. These are good guidelines for us all to follow in order to limit our mercury exposure (I added some notes in italic):

• Do not eat shark, swordfish, king mackerel, or tile fish because they contain high levels of mercury. Those who are not pregnant or nursing can eat up to 6 ounces of high-mercury fish per week. (Though my personal recommendation is to avoid these entirely, but only these)

• Eat up to 12 ounces per week (about 3 to 4 servings) of a variety of fish and shellfish that are low in mercury, such as cod, salmon, shrimp, canned light tuna, pollock, and catfish.

• A commonly eaten fish, albacore ("white") tuna contains higher levels of mercury than canned light tuna because these fish are larger. Limit consumption to a maximum of 6 ounces of albacore tuna per week. (Some brands such as Wild Planet and Vital Choice focus on smaller fish that are naturally lower in mercury, and are certified sustainable)

• For further information about the safety of locally caught fish and shellfish, visit the Environmental Protection Agency's (EPA) Fish Advisory website or contact your State or Local Health Department. A list of state or local health department contacts is available at the EPA website. (My favorite source for seafood information is the Monterey Bay Aquarium’s Seafood Watch)

• Follow these same recommendations when feeding fish and shellfish to your young children, but serve smaller portions. (Once again, I would exclude the higher mercury fish from a child’s diet)

Risk of PCB Exposure

PCBs (polychlorinated biphenyls) are industrial pollutants that find their way into fresh waters and oceans where they are absorbed by fish, and are potential human carcinogens. A recent study reported high levels of PCBs in fish feed given to some farmed salmon, and found that salmon from Europe (Norwegian salmon, for example) had about seven times higher PCB concentration than wild salmon. The Environmental Protection Agency monitors PCB levels in water throughout the country, and more information can be found at the EPA website (6).

Regional Information

For more information on ocean-friendly seafood choices go to the Monterey Bay Aquarium Seafood Watch website, where they rank fish by sustainability and mercury levels. The Monterey Bay Aquarium has done extensive work to label “Best Choice” seafood when it is well managed and caught or farmed in ways that cause little harm to habitats or other wildlife, as well as “Avoid” seafood for those that are overfished or caught or farmed in ways that harm other marine life or the environment, with some alternatives in between. They offer a printable consumer guide with this information by region, so you can make the best choices according to what is available where you live.

With the benefits and risks of eating seafood in mind, here is a summary of the best and worst sea foods when accounting for both human and environmental health:


Wild Salmon (Alaska)
Sardines (Pacific)
Rainbow Trout (Sustainably Farmed in the US, Closed System Aquaculture (CSA)/Recirculating Aquaculture Systems (RAS); or from Minnesota waters of Lake Superior)
Atlantic Mackerel (Not Trawled)


Atlantic Cod

Atlantic flatfish - e.g.: flounder, halibut, sole
Blue crab
Caviar - wild caught sturgeon, especially Beluga
Chilean seabass
SOME Farmed salmon - often called Atlantic or Norwegian salmon. Be careful with the "organic" labeling of salmon – it is farmed internationally and not certified by US standards.
King Mackerel
Imported farmed shrimp
Imported King crab
Orange roughy
Red snapper

Tuna - especially Atlantic Bluefin (light skipjack and albacore from trusted sources can be consumed safely)
Tile Fish

A quick review: Questions to Ask about Your Seafood:

1. Where is it from? Domestic or imported - choose domestic.

2. Is it caught or farmed locally? Choose local foods over those shipped from far away.

3. Is it farmed or wild? Choose wild, unless it is locally farmed under the highest standards and sustainable (see Wild and Farmed fish info above). Avoid farmed, Atlantic and Norwegian salmon.

4. How is it caught? Does the method have high bycatch or habitat damage? (ask if you do not know) - favor fish caught by hook and line, hand line, troll, jig and spear gun.

5. How is it farmed? Choose seafood that has been farmed in the US or Scotland, especially in low or no output, re-circulating systems. Tilapia, shrimp, hybrid striped bass and arctic char are examples of fish that are or are soon to be farmed this way in the US.

6. Is it associated with any contaminants? Mercury, PCB's, antibiotics, etc. The fish that tend to have high levels of mercury are larger species at the top of the food chain, such as: shark, king mackerel, swordfish, tilefish, Albacore tuna, marlin, sea and largemouth bass, red snapper, grouper, bluefish, pike and orange roughy.

7. Is it high in Omega-3s? Best sources of Omega-3s are: anchovies, wild salmon, Pacific and Jack mackerel, Sable fish (black cod), whitefish, Pacific sardine, Atlantic herring, Atlantic mackerel, rainbow trout, light canned tuna.

Seafood tips to get the recommended servings every week:

• Consume plenty of wild oily fish such as salmon and sardines

• Add chopped anchovies to pasta sauce just after you sauté your onions and garlic; the fish will melt away while leaving a mild, subtle fishy taste to your sauce.

• When buying canned products, look for fish packed in water or extra virgin olive oil, in BPA-free cans.

• Most fish can be poached, steamed, grilled, baked, or broiled.

• Avoid fish that is battered and fried (this holds true for most foods!)

• If you are not sure about the source of the fish, remove skin and outer layer of fat before cooking it, as contaminants can be concentrated in these areas.

• Mollusks, such as mussels and clams, should always be alive when purchased with the shells. Shells should be tightly closed or close tightly when gently tapped, and should open when they are cooked. Do not eat any mollusks that are still closed after cooking.

• Use fresh fish no later than 2 days after purchase, or freeze right away if not using within a couple of days. Make sure to cook fish right away if it has been previously frozen.

• Fish is fully cooked when the flakes separate easily; about 10 minutes of cooking time per 1 inch of thickness.

(adapted from from the University of Michigan’s Integrative Medicine Resources and Natural Healing Center)


1. Mayo Clinic: Mediterranean diet: A heart-healthy eating plan

2. Mozaffarian D, Rimm EB. Fish intake, contaminants, and human health: evaluating the risks and the benefits. JAMA. 2006; 296:1885-99.

3. Salmon Farming Problems
Coastal Alliance for Aquaculture Reform

4. University of Michigan’s Integrative Medicine Resources and Natural Healing Center

5. National Listing of Fish Advisories
U. S. Environmental Protection Agency 

6. Polychlorinated Biphenyls (PCBs)
U. S. Environmental Protection Agency

7. Seafood Watch
Monterey Bay Aquarium

8. Fish, Levels of Mercury and Omega-3 Fatty Acids
American Heart Association

9. Summary - PCBs in Farmed Salmon
Environmental Working Group