You have a lot of choices as a consumer. Those choices alter the marketplace. You influence what kind of movies Hollywood produces when you stand in line to buy tickets, debating between an action thriller and a romantic comedy. You alter what ends up in department stores when you decide to buy a blue dress instead of a yellow t-shirt. You pressure companies to be more green when you pick paper over plastic.

Money can move sustainability

And the choices you make when it comes to your dinner, particularly which fish you pick for the 16 pounds of seafood the average American eats every year, drive the fisheries hauling in over 11 billion pounds of fish annually. And that’s just for the US alone.

Choices make a difference, not only from an economic perspective, but from a nutritional and ecological one. So, the short answer to logic of sustainable seafood is that your choice drives markets. The long answer is that it’s good for you and it’s good for the environment – a clear win-win. After all, you wouldn’t be on a nutrition site if you weren’t looking to eat and be healthier, right? So why not eat in a way that’s healthier for yourself and the rest of the ecosystem?

Making the Smart Choice: Seafood and Nutrition

You know that you’ve made a nutritional choice when you decide to buy that bag of apples instead of a bag of Doritos. But did you know that you made a nutritional choice when you picked salmon instead of tuna? A lot of nutrition talk just refers to “fish”, as if all fish are the same nutritionally.

But, you say, that’s true. After all, fish is fish… right?

Tuna, swimming – thanks to Flickr user Canales

Well, it’s partially true. All fish, from anchovies to yellowtail, have a few key nutritional ingredients that are fantastic for you. The American Heart Association, for example, recommends that we eat fish at least two times per week for a healthy heart.

For one, fish are a great source of protein that contain far less fats than other meats like beef and pork. They are a complete protein, which means that they contain all of the essential amino acids that we need to eat in our diet. Why is protein so great?

As I’ve said before, protein and the amino acids it contains are key to making our bodies function properly. Protein calories also make us feel fuller, longer compared to calories from fat or carbohydrates, thus allowing us to eat less.

Fish are also great sources of Omega-3 Fatty Acids, a group of unsaturated fatty acids that have been linked to all kinds of health benefits, from reduced cancer risk to increased intelligence. While we tend to demonize fats, the truth is that some are good for us, and Omega-3s are among the good guys. In fact, they’re so good for the brain that the Rush Institute for Healthy Aging claims that people who eat at least one meal of fish per week will be significantly less likely to develop Alzheimer’s disease than those who never eat fish – a statement that, at least in part, is backed by science.

When a Fish Isn’t Just a Fish

But not all fish are the same – not even close. Just like lamb, beef, and venison all have differing amounts of protein, fat and calories, so, too, do different species of fish. Sockeye salmon will get you 3.8 grams of protein per ounce, while a nice tuna steak provides 9 grams per ounce. A skinless, 3 oz portion of Halibut will run you 110 calories, with 20 of them coming from fat, but the same portion of Mackerel will give you a whopping 210 calories with 120 of them from fat. That’s a difference of 100 calories from fat alone in a single piece of fish!

A Cutthroat Trout – beautiful fish, courtesy of flickr user fool-on-the-hill

Before you freak out about the high fat content, note that while Omega-3 fatty acids are found in every kind of fish, they are especially high in fatty fish. That Halibut only contains 0.7 grams of Omega-3s, while the fatty Mackerel has 2.6 grams. As with anything else, it’s all about balance, and getting the right amount of fat and protein into your diet, not aiming for the lowest-fat option.

Not even all types of similar or even the same fish are created equal: take tuna for example. Buy canned light tuna, and you’re looking at about 33 calories and 7.2 grams of protein per ounce. Canned white albacore, however, contains roughly 37 calories and only 6.8 grams of protein per ounce, plus an extra 0.8 grams of fat. Opt for a cooked tuna steak and you end up with 40 calories, 9 grams of protein, and 0.5 grams of fat per ounce. Even your choice of tuna sashimi makes a difference: Bluefin will net you just over ten more calories and one gram of fat per ounce than Ahi. Though these might seem small, scientists have found that even a change of 100 calories a day can impact your weight dramatically. Subbing in Bluefin for Ahi at a ten-ounce tuna meal is enough to make a difference.

Fish Toxicology

There are issues far worse than protein and calorie counts to think of when choosing fish. That’s because, unfortunately, fish are the final resting places for many of the chemicals that we pollute our waters with everyday. Water treatment has lowered the levels of some of these, but the problem is that fish biaccumulate these toxins. Bioaccumulation occurs when a substance is absorbed or stored at a faster rate than it is lost, causing it to ‘accumulate’ in the body. Thus, smaller environmental levels can become higher ones in the body.

The analogy I used before when explaining bioaccumulations is with drinking alcohol: normally, you can drink one beer in an hour and be fine. Drink twenty in an hour, and you probably will experience acute alcohol poisoning, but assuming you recover, you’ll again be fairly fine (minus some liver damage). But instead, imagine if every time you had a drink, your body simply couldn’t get rid of the alcohol, and it lingered in your tissues. You could have only one drink a week, but still within a few weeks, you’d be drunk all the time.

Bioaccumulation up close

That’s how bioaccumulation works. The fish’s body removes the toxins at such a slow rate (or not at all) that they build up to much higher concentrations than are found in the water around them. And it gets worst as you go up the food chain – those fish at the bottom get a certain level of toxin, but then they’re eaten by bigger fish. When that big fish eats 10 little fish, suddenly it has 10x the concentration of toxins that the little ones did, and so on and so forth to the top of the chain (here’s a hint – that’s where we fit into the food web).

Toxins that are particularly dangerous in fish include many of the chemicals in plastics (see our previous details on the nutritional consequences of PBDEsPhthalates and BPA) as well as many others caused by industrial and agricultural pollution, like DDT. One of the major toxins that fish bioaccumulate is mercury, which is released from the process we use to turn coal into energy. Mercury levels in fish can be so high that the FDA and EPA monitor the levels in common varieties of fish to set healthy safety standards.

Already, there are a number of fish that have such high mercury levels that they are considered unsafe to be consumed by pregnant women. These include:

  • sharks
  • king mackerel
  • swordfish
  • tilefish.

Tuna Sushi, be careful now

But even those that are commonly found on our dinner plates can be high in mercury. Sushi tuna, for example, is one of the worst offenders; it can have up to 0.64 parts per million of mercury, which is only a hair under the 0.73 found in king mackerel. Mercury levels are high enough in fish to trouble even healthy, non-pregnant adults. Just ask Jeremy Piven – he was diagnosed with a blood mercury level six times above the upper limit of safety while working on a Broadway show after regularly consuming sushi with tuna in it.

When thinking about the nutritional side of choosing fish, you have to weigh the good with the bad. While swordfish is high in Omega-3s, for example, its mercury level is enough to strike it off the ‘healthiest options’ list (although the EPA give the green light to anyone who isn’t pregnant, planning to become pregnant or nursing to eat up to 7 ounces of high-mercury fish per week, if you want to trust them). You want something that contains what’s good for you and as little of what’s bad for you as possible. It should be the same with sustainability. You can pick fish that are good for you and good for the environment – you just have to know which ones to choose.

Making the Even Smarter Choice: Seafood and Sustainability

Since you already have a lot to consider nutritionally when choosing seafood, why should you add sustainability into the mix? Well, the easy answer is you have to, if you want your children and grandchildren to be able to enjoy the same healthy choices you can now. The global catch of wild fish leveled off over 20 years ago and 70% percent of the world’s fisheries are being harvested at capacity or are in decline. It’s estimated that we’ve removed over 90% of the large predatory fish like sharks from the world’s oceans already, and some of the biggest fisheries are on the verge of complete collapse. But perhaps the simplest reason as to why you should factor sustainability into your seafood choices is that it’s easy to and, to boot, still good for you.

Part of why nutrition and sustainability fit so well together is that those fish that tend to be high in toxins just happen to be those that we’ve overfished. You see, bioaccumulation is a time-consuming process. The older and larger a fish is, the more toxins it’s likely to have bioaccumulated. In general, this means that the biggest fish in the sea that are highest up on the food chain are the most likely to have the highest mercury levels.

Maybe we should just leave the tiger sharks in the ocean?

But the biggest predatory fish are also the slowest growing and least able to rebound from intense fishing pressure. They’re the ones that take years to develop into maturity and have fewer offspring than their smaller cousins. It’s like comparing rabbits to moose – if you have a population of rabbits and you take away half of them, you might not even notice that any were taken once they’re done breeding like, well, rabbits. But take away half of a population of moose and it may take years for them to replace their lost numbers.

While most of what we hear about the fishing industry is doom and gloom when it comes to being eco-consious, there are fisheries being run in a sustainable way. The more we purchase from those fisheries, and not from the other ones, the more we will pressure the remaining industries to improve their practices and solve the most pressing issues, including overfishing, illegal and unregulated fishing, habitat damage, bycatch and poor management.

So how do you know what fish to buy?

Just ask the Monterrey Bay Aqauarium. Born out of a modest exhibition called “Fishing for Solutions,” the Monterrey Bay Aquarium’s Seafood Watch Program is one of the largest and most extensive sustainable seafood programs out there. They provide pocket guides for all over the United States that give a simple classification to the types of seafood you’re likely to see in your area. They break fish options into three categories: Green for Best Choices, Yellow for Good Alternatives, and Red for those to Avoid. At the grocery store in California and can’t decide between Rainbow Trout and Monkfish? Check the colors. Green means go on the trout!

Turning the Tide, the Monterey Bay Aqaurium’s new publication about overfish – click to read

These simple categories factor in all kinds of information, from stock status and vulnerability to fishing pressure to the nature and extent of the bycatch created by the fishing method. And they aren’t limited to rating just wild-caught species. Aquacultures and farmed fish are rated on their use of marine resources, risk of escapes, disease & pollution, and overall management. All this info is packed neatly into fresh pocket guides twice a year, giving you the most up to date information on which fish are environmentally friendly and which are not. With some fish, the method is really what counts (like Cod). If you’re not sure what method your fish is fished with, check the packaging or ask the guy behind the fish counter. If it isn’t listed, and they can’t tell you, then pick an option you’re sure is a good choice instead. Many stores, though, will have it right on the package if its wild-caught, farmed, or local.

The one thing that doesn’t factor into the guides is the relative nutrition of the species from our perspective. While some do have health warnings, generally speaking, the guides are designed to talk about what choice is good for ocean health, not human health. This is, of course, until recently, when Seafood Watch announced its “Super Green” list. This group are the creme de la creme of seafood choices – they’re the most sustainable fish that also happen to be high in long-chain Omega-3 fatty acids and low in environmental contaminants like mercury. This effort draws from experts in human health, notably scientists from the Harvard School of Public Health (HSPH) and Environmental Defense Fund (EDF), to combine the best of both worlds: sustainability and good nutrition.

Note: Both charts can be re-categorized by clicking on the column headings

Seafood Watch List, Super Green List (as of October 2009)

Fish Growing Method Source
Albacore Tuna Troll or Pole-caught US or British Columbia
Mussels Farmed Anywhere
Oysters Farmed Anywhere
Pacific Sardines Wild-caught Pacific Waters
Pink Shrimp Wild-caught Oregon
Rainbow Trout Farmed US, likely
Salmon (any variety) Wild-Caught Alaskan
Spot Prawns Wild-caught British Columbia

Full list can be found on our website:

Other groups have put out similar lists that highlight both nutrition and sustainability. One of the other great ones is produced by the Washington State Department of Health. Their “Healthy Fish Guide” lists the fish that are lowest in contamination, with special notes to those that are high in Omega-3s and warnings in orange that show a particular fish or method is unsustainable. In general, these user-friendly guides allow us to make smarter choices that improve our lives while decreasing the impact we have on our environment.

As always when buying fish, be sure that it’s properly stored and/or fresh (for tips on how, check out the FDA’s page on seafood). If you’re buying frozen fish, here’s a tip I learned from my grandmother – try defrosting it in milk. The fish turns out much more tasty, flaky and moist (at least from my experience)! And if you’re looking for some great recipes for the Super Green options, check out the Seafood Watch’s recipe site. They’re adding new ones every month to promote people to eat their choices for the most sustainable healthy seafood. In turn, your smarter choices at the grocery store will hopefully convince the money-minded fisheries managers that sustainability is important, and they will stop over harvesting our oceans so that there’s plenty of fish for generations to come to enjoy.

Read Turning the Tide – put out by the Monterey Bay Aquarium.  It will teach you about the current state of the oceans as they relate to seafood production and how we can move towards more sustainable solutions:

Special thanks to Alison Barratt, Communications Associate Manager at the Monterey Bay Aquarium, for giving me the full info on sustainable seafood!