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Good Fish, Bad Fish

December 23, 2011

Fish are a paradoxical food in our society.  On the one hand, the American Medical Association exhorts us to eat more of them on a daily basis, since they provide a much leaner source of protein than conventional meat and come loaded with beneficial omega-3 fatty acids.  On the other hand, Americans never were much of a fish-eating society except for specific subcultural pockets, fish frequently come with warnings about how they come loaded with toxic mercury in their flesh and limits on how frequently you should eat them to be safe.  Add in the issues of overfishing and environmental destruction of Earth’s oceans, and trying to figure out what you should and should not be eating becomes a hassle that most people would rather avoid.

Ignoring the issues don’t make them go away, however.  Let’s look at each of them a little closer, and see what, if anything, can be done.

The Last Wild Food

“Planet Ocean Sphere” by Ray Troll, from

Part of the problem with fish is that even in an age where aquaculture is increasingly common, very few species are actually domesticated.  Most fish are caught from the wild, making them susceptible to environmental damage both on land and in the sea.  My last post discussed the issues of garbage in the ocean and photodegraded plastics, an issue which is currently being researched to determine if these plastics are working their way back up the food chain into us (the little plastic pieces have already been found in fish that humans eat)1.  Mercury, the reason behind the warnings on many fish, is also primarily derived from terrestrial sources.  About two-thirds of all elemental mercury in the ocean is produced by man, with the largest culprit being the burning of fossil fuels, particularly coal (160 tons a year in the U.S. alone)2.  Mercury is released as particulates into the atmosphere after burning, and rainwater washes the mercury particulates into the ocean where it is thought that midwater bacteria may be converting it into toxic, biologically-active methylmercury, although the exact pathway by which elemental mercury enters the food chain is not currently clear.2

Anadromous or catadromous fish – those that spend part of their lives in seawater and part in freshwater – are susceptible to environmental degradation around the streams that they spend part of their lives in.  Salmon are probably the best known example, as they spend most of their lives at sea but must return to fresh water to spawn.  Damming of salmon rivers or deforestation around the edges of the streams, allowing more sediment to wash into the water and water temperatures to rise without the protective shade of the trees, can and have destroyed entire salmon runs throughout the United States.  The Atlantic salmon, as common as it is to see for sale at fish market counters, is almost extinct in the wild.  All of the individuals sold today are farmed fish, as the American East Coast lost its salmon to industrial development long ago.  West Coast salmon in the continental U.S. are also in dire straits, with the Columbia River containing 3% or less of the salmon it once held when Lewis and Clark arrived in the region and the Sacramento chinook population currently nosediving3.

Sardines drying in the sun, Monterey, CA, 1908
Sardines drying in the sun at Monterey, 1908.

Even for fish that don’t live in fragile freshwater habitats, the future is often bleak due to overfishing.  Market demand for fish can easily exceed the abilities of wild populations to reproduce themselves, especially if the species in question is long-lived and late-spawning.  Unlike mammals, many fish reach their reproductive peaks late in life when they are older and larger – precisely the point at which most fisheries are likely to target them.  Deepwater fish such as the slimehead (market name: orange roughy) or Pacific rockfish (market name: red snapper, Pacific snapper) live for a very long time, with some species having an estimated lifespan of 100 years or more.  With such long lifespans and limited habitat to fill, they may not reproduce before they are 15 or 20 years old in the rockfish4, and perhaps 23-40 years in the roughy5.  Even fish that are low on the food chain and reproduce rapidly can easily be overwhelmed, with crashes occuring even in enormous and fast-replacing populations such as the California sardine fishery (1950s), the Peruvian anchoveta fishery (1970s), and Newfoundland cod (1990s).  Fish catches of all species worldwide peaked at 78 million tonnes in 1988 and have been declining by about half a million tonnes a year since6.

In our increasing desperation to collect the last remaining wild fish, those fish and crustaceans that live in deep water or on and near the ocean bottom are frequently collected by trawling – dragging heavy, weighted nets across the seabottom to literally scrape the seafloor clean, a destructive and bycatch-heavy method to collect seafood that has been likened to clearcutting the oceans, or, to put it in more graphic terms, “using a bulldozer to catch songbirds for food.6”  Trawling has already damaged 40% of the coldwater reefs off of Norway, obliterated 90% of Florida’s fragile coral reefs, and can reach seamounts one and a half miles below the surface, scouring an area twice the size of the continental United States.  This destructive industry is not even economically sustainable; the world’s governments subsidize the trawler fleets with $152 million in taxpayer money, without which they would operate at a loss6.

The Tragedy of the Commons, espoused by Garret Hardin in 1968, is hard at work in Earth’s oceans as every industrialized country on Earth races to grab all the fish it can before anyone else does – to the detriment of all, but particularly those poorer countries that depend on wild fish simply to meet their protein requirements.  A terrible example is the oceans off the coast of West Africa, where Europe has leased the right to fish from the political leaders of these poverty-stricken nations and proceeded to strip the oceans of the fish that the local people depend on.  In countries where 50% of the dietary protein once came from fish, European trawlers have halved the local populations of shrimp, squid, and hake, driven others into local extinction, and are ravaging the sardine populations that lie near the base of West Africa’s oceanic food chain to fatten tuna for wealthy consumers at sushi bars in Los Angeles and Tokyo6.

To Farm or to Fish

If catching wild fish obliterates the habitat for them and everything else that lives in the area, strips populations of their adults before they have a chance to breed, and frequently catches unintended species (e.g. bycatch) and then throws it back to die, wouldn’t farmed fish be the answer to relieve the pressure on wild stocks?

Well, yes and no.  Whether the farmed fish fixes problems or simply adds more to the list depends a great deal on the type of fish it is, and part of the problem is the types of fish we typically eat.

Americans are not very adventurous types when it comes to seafood.  Shrimp is the most popular, with 4.4 pounds consumed on average per capita by 2006, or 1.3 billion pounds annually (and that just in the U.S.)7.  Although catching wild shrimp can be exceedingly destructive – shrimp are bottom-dwelling, and thus trawler-caught, animals – most of what we eat nowadays is farmed in developing nations such as Vietnam, India, Indonesia, Sri Lanka, and China6.  Where those farms stand now, extensive mangrove forests once stood, once a haven and a nursery for many of the fish species that locals depend on for food, and a protective wall against the destructive energy of typhoons and tidal waves.  If they occur farther inland they replace rice paddies that once produced food for the local people, and the salty water that the shrimp require to survive can and does leak out, rendering the local water supplies too salty to drink or grow food with.  The shrimp they raise is frequently caught as wild, tiny fry using mosquito nets, producing horrendous amounts of bycatch in the young of other species and stripping the wild populations of their replacements6.  And to make matters worse, since shrimp are detritivores (scavenging bottom-feeders) they must be fed fishmeal, which comes from wild stocks.  Approximately two pounds of wild fish must be sacrificed to produce one pound of farmed shrimp6.

From Ray Troll’s website,

This is not simply an issue in shrimp, either.  Many of the flagship fish that we farm – the Atlantic salmon, the European seabass/Branzini, and more recently our attempts at fattening (and even farming) wild tuna – were chosen not for their ease in domestication, but for their popularity as food7.  Unfortunately, most of the fish we eat are predators, and in the case of tuna sit extremely high on the oceanic food chain, making eating them the equivalent of eating something that preys exclusively on lions and tigers.  In the case of our most common farmed fish, salmon, we’ve attempted to bypass part of this problem by supplementing its fishmeal diet with “poultry meal” – all of the nonfood parts left over from processing feedlot chickens such as blood, necks, feet, and intestines – as well as chicken manure and the normally indigestable feathers6, ensuring that any pesticides, antibiotics, or other chemicals that get into them then get passed into the fish as well.  Farmed fish thus not only use up perfectly edible wild fish, but they often inherit the problems of industrial farming on land as we attempt to make up the protein shortfall with the less palatable leftovers from our factory farms.

Farmed fish, then, only produce a net gain in available food when they are species that feed at low trophic levels; herbivores or filter-feeders, in other words.  Fish such as tilapia, catfish (American and Basa), carp, and barramundi meet this criteria, as do farmed shellfish such as oysters, clams, and mussels  Still, you have to be careful as to where your seafood comes from, as aquaculture in other countries frequently makes use of pesticides, piscicides, and antibiotics to ensure that their crop survives the overcrowded conditions often found in farming.  Farmed shrimp, like many other farmed fish, come treated with diesel oil, chlorine, and antibiotics – many of them banned in the U.S., such as chloramphenicol or nitrofurans6.

For some species, farmed fish aren’t just a suboptimal choice, but a dangerous one.

Eating Down the Food Chain

If after all this you’re feeling a bit queasy about the idea of eating seafood, don’t.  The primary problem facing fish eaters is the same one facing anyone that eats farmed meat (or anything at all, really), and that’s a lack of information about the way our food was produced or procured.  The issues with farmed fish mirror those seen in factory farmed mammals and birds: environmental degradation due to overconcentration of the animals and their wastes; overuse and abuse of antibiotics, many of them hormone disruptors at best and all of them selecting for antibiotic-resistant bacteria at worst; and the deliberate lack of information on the consumer side as to the conditions in which the animal was raised and killed.  There are additional issues to consider with wild fish, mostly having to do with how they are caught and how resilient the wild population is to fishing.  That said, keeping a few guidelines in mind can help make it easier to find good, healthy, and environmentally-friendly fish.

  1. Eat Lower on the Food Chain – In addition to the worries about methylmercury, the simple reason to avoid eating large predators is that they are top predators.  Predators reproduce themselves slowly since there needs to be less of them than their prey, and while predatory fish can still produce many offspring at a time, most of them will not survive to the stage at which we like to eat them.  While this doesn’t mean that you have to cut them out of your diet  it does mean that we need to stop viewing fish such as salmon or tuna as equivalent to chicken and trying to farm them as such.  Herbivores (sardines, tilapia), filter-feeders (mussels, clams), wild detritivores (Eastern lobster, dungeoness crab), and low-level predators (jellyfish, mackerel, squid) should make up the bulk of anyone’s seafood meals.  Not only are these fish more numerous and generally more resilient to fishing, but because they are lower on the food chain, the mercury in their flesh is far less concentrated (and dangerous!) than it is in big predatory fish.   This rule also encompasses the idea of eating less protein at a sitting, or using meat (whether terrestrial or marine) as an additive in a recipe rather than the main course.  This reduces pressure on fish stocks even indirectly, as fishmeal is fed to farmed land animals as well as fish8.
  2. Avoid Long-Lived Fish – This overlaps somewhat with number 1, as predatory fish can live a long time (tuna can live for 15 to 30 years or more).  But there are fish out there that live even longer, such as the orange roughy or Pacific rockfish.  These should never be eaten, since there is no level at which you can fish these animals and maintain an economically-viable fishery.  If eating tuna is like eating a tiger’s predator, then eating these fish is like eating elephants.  Both fish and elephants live long, breed late, and breed slowly.  They are not adapted to heavy predation and cannot survive being fished at levels that are economically viable.
  3. Do Your Homework – This sounds like asking a lot, but as I noted before it’s really no more than you should be doing with the rest of your food as well.  Know which fish are under too much pressure and should be avoided, which fish you should never eat, and which fish you can only eat if they come from certain countries or are caught in certain ways.  Ideally you would know how they were caught in all circumstances, but the people behind most fish counters are unlikely to know since most people don’t think to ask.  In such cases it may be safest to stick to choices that are generally easy to recognize like “farmed tilapia” or “wild-caught Pacific salmon.”  The Monterey Bay Aquarium provides a good list of which seafood represents your best choices and why.

Ultimately, the onus is on us to be informed consumers and to apply both market pressure (to shift fishing away from overfished or badly-fished stocks) and political pressure (to stop the artificial subsidies that are all that keep the world’s great industrial fishing fleets afloat) to ultimately change the way seafood is brought to market.  There’s already a shift in the way that meat is being produced, with grass-fed becoming more common of an option where once it had disappeared under the drive to produce more, faster, and cheaper.  We must do the same for fish, or there will be literally nothing left in the ocean but oozes and jellyfish, and one of the world’s most dependable sources of food will have been devoured in a 20th-century blitz of greed and shortsightedness.

More than 70% of our planet’s surface is covered in water.  It is time we took better care of it, so our children will still find that there are plenty of fish in the sea.

A school of anchovies, from




3. Tucker, A.  2008.  “On California’s Coast, Farewill to the King Salmon.”  Smithsonian Magazine, October 2008, accessed online at

4. Fisheries and Oceans Canada, 2008.  “Protecting British Columbia’s Rockfish.”  Accessed online at

5. Lack, M., K. Short and A. Willock, 2003.  “Managing risk and uncertainty in deep-sea fisheries: lessons from Orange Roughy.”  A WWF/TRAFFIC Oceana report, accessed online:

6. Grescoe, Taras. 2008.  Bottomfeeder: How to Eat Ethically in a World of Vanishing Seafood.  New York: Bloosmbury USA.

7. Greenberg, P.   2010.  Four Fish: The Future of the Last Wild Food.  New York: Penguin Press.

8.   Miles, R.D. and J.P. Jacob.  1997.  “Fishmeal in Poultry Diets: Understanding the production of this valuable feed ingredient.”  University of Florida, Institute of Food and Agricultural Sciences.  Accessed online at

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