September 12, 2009
Half Of Consumed Fish From Aquaculture

On the surface this sounds like goods news since you might expect aquaculture fish to reduce the pressure to over-harvest wild fish. But no.

Aquaculture, once a fledgling industry, now accounts for 50 percent of the fish consumed globally, according to a new report by an international team of researchers. And while the industry is more efficient than ever, it is also putting a significant strain on marine resources by consuming large amounts of feed made from wild fish harvested from the sea, the authors conclude. Their findings are published in the Sept. 7 online edition of the Proceedings of the National Academy of Sciences (PNAS).

"Aquaculture is set to reach a landmark in 2009, supplying half of the total fish and shellfish for human consumption," the authors wrote. Between 1995 and 2007, global production of farmed fish nearly tripled in volume, in part because of rising consumer demand for long-chain omega-3 fatty acids. Oily fish, such as salmon, are a major source of these omega-3s, which are effective in reducing the risk of cardiovascular disease, according to the National Institutes of Health.

The problem: salmon and other aquaculture fish are fed with wild fish.

In 2006, aquaculture production was 51.7 million metric tons, and about 20 million metric tons of wild fish were harvested for the production of fishmeal. "It can take up to 5 pounds of wild fish to produce 1 pound of salmon, and we eat a lot of salmon," said Naylor, the William Wrigley Senior Fellow at Stanford's Woods Institute for the Environment and Freeman Spogli Institute for International Studies.

The amount of fish oil in the aquaculture salmon diet could be lowered. But this seems like an inadequate response in the face of rising demand.

One way to make salmon farming more environmentally sustainable is to simply lower the amount of fish oil in the salmon's diet. According to the authors, a mere 4 percent reduction in fish oil would significantly reduce the amount of wild fish needed to produce 1 pound of salmon from 5 pounds to just 3.9 pounds. In contrast, reducing fishmeal use by 4 percent would have very little environmental impact, they said.

What is really needed: Genetic engineering to get land-based crops to produce the omega 3 fatty acids DHA and EPA. Note that flax oil does not contain these long chain omega 3s. Flax contains Alpha Linolenic Acid.

Update: Some people in the salmon aquaculture industry say that they use 5 lb of feed with only 1.5 lb of that fish meal to produce 1 lb of salmon. That's not as bad as Naylor's 5 lb of fish to create 1 lb of salmon. Still, the ratio of fish meal to salmon has got to get well below 1-to-1 in order to take pressure off the oceans.

Share |      Randall Parker, 2009 September 12 07:54 PM  Trends Resource Depletion

Fat Man said at September 12, 2009 9:02 PM:

Just another example of environmentalists trying to be the problem, rather than solve a problem. Why not feed greenpeace to the fishes?

Mthson said at September 12, 2009 9:11 PM:

Grow meat in bioreactors and save ourselves a lot of trouble.

Brett Bellmore said at September 13, 2009 9:31 AM:

Common purslane is fairly high in EPA, at 0.01mg/g, though it's mostly a source of alpha-linolenic acid. Tastes good in salads, too.

But why not go directly for the prize, and genetically engineer our intestinal flora to produce omega 3s?

James Bowery said at September 13, 2009 4:09 PM:

Domestic critters tend not to be competitive in the wild.

not anon or anonymous said at September 14, 2009 7:42 AM:

I agree with mthson. We should grow fish feed in bioreactors, or find other alternative sources for it; and the article points to several promising efforts in this direction. Also, vegetarian fishes can be grown on a plant-based diet.

Nick G said at September 14, 2009 10:43 AM:

Humans only convert 2-5% of Alpha Linolenic Acid to DHA, but my understanding is that chickens convert 40%. Chickens are also much more efficient at converting food into meat than either salmon or beef.

So, just feed flax to chickens, and eat the high DHA eggs.

spindizzy said at September 14, 2009 2:17 PM:

I'm pretty sure I have read that farmed fish are much lower in Omega 3 because of the diet. said at September 14, 2009 5:44 PM:

How about genetically engineered sea borne algae that produces Omega 3 and feeds on human pollution and sunlight? Too sci-fi?

Randall Parker said at September 14, 2009 7:30 PM:


Algae that grows in the ocean has been selected to be most successful by many millions of years of evolution. If you try to create a genetically engineered algae that grows in the ocean and performs some special function the odds are high that it will be out-competed by wild type.

If the genetically engineered algae is not out-competed by wild type you run the risk of changing the entire planet's ecosystem in some unexpected and quite possibly undesired way.

Algae genetically engineered to excrete oil might some day be grown in land ponds. My guess is that that's the only way to make algae biodiesel economically workable. But even in ponds the genetically engineered algae would run the risk of getting out-competed by contaminating organisms. So likely it would be necessary to genetically engineer the algae to be able to survive in the presence of some toxin that wild type couldn't handle. Or the ponds would need to be glass-covered and hence more expensive to build and maintain as well as probably letting less light thru.

Douglas said at September 18, 2009 5:47 PM:

Or increasing the volume of biomass in the oceans allowing for a greater feed environment for wild fish, and increasing total output in wild and natural routines.

Stop composting, start, dumping biomass into the ocean.

Douglas said at September 18, 2009 5:49 PM:

Don't geneticaly engineer anything. Just feed the oceans.

Just feed them.

Larry said at September 18, 2009 7:01 PM:

- Aquaculture is growing explosively. When I last looked at it, I didn't call it to get to 50% for another 5 years or so. If it tripled in the last 12 years, what will it look like in another 12? A recent trip had me flying over Bali and other Indonesian islands, which feature endless acres of fish ponds. Lots of acres left, though.

- While feeding fish to fish will put pressure on some stocks, it is likely to relieve pressure on some of the fish - such as salmon - that humans so like to eat, because fish don't care as much on what kind of fish they dine. All things considered, that's a good thing.

- Douglas has it right that it's long past time for us to convert the oceans from a hunting ground into "pasture", effectively domesticating and nurturing its critters, then to enjoy the vast growth in output that that will imply.

WuzzaDem said at September 18, 2009 7:22 PM:

Is there one example of human ingenuity & success that pleases environmentalists? Even one?

They don't like agriculture & cheap food, suburbs, gasoline & cheap houses, deisel, gasoline & cheap transportation, coal, petroleum, fission, fusion, or any sort of reliable energy, high birthrates, low death rates, Norm Borlaug's Green Revolution, genetically modified crops, the bounty of capitalism, big homes, big yards, big cars, big families, big TVs, faraway vacations, jet travel, inexpensive shopping chains, Christianity, Judaism, highways, fast food, freedom, choice, prosperity, and - let's be honest - humans.

The earth was PERFECT until humans came along and boloxed up all that perfectness ...

not the fat man said at September 18, 2009 7:32 PM:

Farmed fish, largely because of the fish oils, have significantly higher levels of bio accumulated toxins. reducing the amount of fish oil in farmed fish diets would help somewhat (but not completely) with this. farmed fish also, particularly in the case of salmon, spread disease (sea lice in salmon's case) to nearby wild fish populations, in some cases devastating them. It is true they dont do so well in the wild,but sometimes escape, and interbreeding with wild populations is a problem.

Everyone know that farmed salmon are grey (or white), not pinkish orange? dyes are added to their feed to get that more natural salmon looking color. from carotenoid pigments, largely astaxanthin, and canthaxanthin. (some studies cast aspersions upon anything more than small amounts of canthaxanthin due to possible eye problems. probably have to eat a lot of salmon though, but it's unclear.)

It's produced a lot of cheaper food, but aquaculture's not necessarily all that great a thing yet, on balance.

---squindizzy, I have read several places that farmed fish are lower in omega 3's but am not totally sure, but they are higher in overall fat content (but not in good fat.)

Randall Parker said at September 18, 2009 7:36 PM:


I do not expect aquaculture to displace ocean fishing. Rather, total fish consumption will rise and more ocean fish will be caught to feed aquaculture fish.

Until aquaculture fish can be fed entirely using land crops I do not see aquaculture lowering the pressure on wild fisheries.


Norm Borlaug's Green Revolution allowed huge increases in available food without countries going thru industrialization. This caused population explosions. Since there are many more people in the world than there were when the Green Revolution started we might even have more hungry people now than we had when the Green Revolution first began.

not the fat man said at September 18, 2009 8:01 PM:

wuzza dem

what a phenomenon. in real life, you probably have a functioning view of things. but in politics -- and for some reason environmental issues have to creep into that? -- all sense of perspective, and even some reality, just flies out the window?

this statement about environmentalists:

"They don't like agriculture & cheap food, suburbs, gasoline & cheap houses, deisel, gasoline & cheap transportation, coal, petroleum, fission, fusion, or any sort of reliable energy, high birthrates, low death rates, Norm Borlaug's Green Revolution, genetically modified crops, the bounty of capitalism, big homes, big yards, big cars, big families, big TVs, faraway vacations, jet travel, inexpensive shopping chains, Christianity, Judaism, highways, fast food, freedom, choice, prosperity, and - let's be honest - humans."

it's just brimming with falsity, and even blatant ridiculousness. yeah, I can make some stereotypes about "environmentalists" too, grabbing a few random examples from here and there. but most of what you say above is so profoundly ignorant, that its well,, well i guess it aptly illustrates why we have such f'd up policies to begin with -- in a country tha this decades writes too many laws, and the ones it does write are pretty bad. we have ignorance running amuck. speaking of which, you simply HAVE to be a glenn beck watcher. hands down, its a freakin lock. no one can be this incredibly, profoundly ignorant ona prevalent, "politicized" topic, without watchin' a whole lotta beck.

hands down. just a bunch of crap. like I said, its prolly just a reflection of how biased and "led" by all the rhetoric crap we hear, our thinking has become.

I AM the fat man said at September 18, 2009 10:38 PM:

not the fat man:
Ad hominem is the very lowest form of settling an argument.
It reveals a paucity of intellectual capital.
Kindly learn to spell, and , if you intend (when you are older) to learn to write , punctuating your points with profanity is a poor start , in fact it is "ignorance running amuck"
The correct word is "amok".
You and your frater idioticus , wuzzadem , reveal why environmentalism has become an object of ridicule , rather than rigorous scientific debate.

N Speller said at September 19, 2009 1:34 AM:

Amok is a variant of amok. Leave the guy alone with your ad hominem attacks.

Kevin said at September 19, 2009 11:16 AM:

Meh. Soon it will be cheaper to raise the plankton eating fish that are currently caught in the wild to feed the farmed fish. The problem will be solved by the invisible hand.

RM3 Frisker FTN said at September 19, 2009 5:45 PM:

I recommend Soylent Green. I am told it is made from "high-energy plankton" ...

epobirs said at September 20, 2009 1:01 AM:

not the fat man.

Fact is, several prominent persons in environmentalist circles speak very approvingly of human extinction. It is also a popular meme among the animal rights types, notably the leaders of Peta. Those who want the species to continue at all tend to think a few million humans across the entire globe living in small tribal groups is the most that should exist. This is a genuine sociopathic psychosis expressed for anyone who cares to listen but these nutters are regarded as serious voices.

You'll have a very hard time finding any respectable opponents who speak favorably of paving the whole planet, other than in jest.

epobirs said at September 20, 2009 1:26 AM:

Randall, countries experienced population explosions before being reached by Borlaug's work. Africa is a perfect example. The obstacles to the Green Revolution there were combined with a burgeoning population to create devastating famines. This recent book, discusses the problems of Africa in some detail, starting with Borlaug's accomplishment elsewhere and why it ran into a wall in Africa. (Mostly a combination of malfeasance and stupid policies on the part of those claiming to help.)

Population growth in Africa is a remarkable thing. Famine, disease, war, nothing that induces massive premature death has done more slow the increase of humankind there. It goes to show how dramatic a few innovations in food production and medicine can be even in dire conditions.

Paul Molyneaux said at October 8, 2009 12:13 PM:

Selling Aquaculture

When Science Daily, The Washington Post, and leading sources of information all over the US, broadcast, without question, the story that almost half the seafood consumed in the world comes from aquaculture, it’s hard not to feel like the fix is in.
The United Nations collects the data that gave rise to this grand announcement: yet, nowhere in the articles extolling aquaculture’s virtues and minimizing its costs, is there any mention of China’s dubious statistics, which account for over 60 percent of the 51 million tons of global aquaculture production, or that 8 million tons of this amount are mollusk shells (hard to eat no matter how long you boil them).
In the world outside China, aquaculture provides less than 24 percent of the fish consumed, an increase of only 3 percent over the last decade.
Include indirect consumption of the wild caught fish used to feed the dominant aquaculture species and the percentage of aquaculture’s contribution to the world’s seafood supply decreases as aquaculture expands. In the case of salmon—and other carnivorous species in the pipeline for US offshore fish farms—it requires an average of 5 pounds of wild caught fish to grow one pound of farmed fish. So as this form of aquaculture increases we indirectly consume 5 times as much wild fish as farmed. Aquaculture’s percentage of world seafood consumption actually contracts as these industries expand.
The math is simple, a question journalists might want to ask is why aren. Fewer still are accurately tallying the environmental and social costs of producing high value species such as shrimp and carnivorous fish, but that’s a much lengthier letter.
Paul Molyneaux
Author of “Swimming in Circles: Aquaculture and the End of Wild Oceans”

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