Whenever my older brother sees me eating some dessert, like a piece of cake, he informs me that I might as well just tape it to my thigh.  This is always followed by an imitation of the sound of me running in corduroy pants (Vtt! Vtt! Vtt! You’re going to start a fire!).  Since my mouth is usually full at this point, I have to forgo my customary witty repartee and give him a charlie-horse (or the elbow version of the charlie-horse, which is the monkey-bump).

Outside of the realm of sibling hi-jinks, do people really believe that eating a pound of food will result in a full pound of body weight gain?  Hmm… Do you?  I’m guessing not.  You know that it takes much more than that – and it depends on the type of food consumed, level of physical activity, and variations in  individual physiology.

In the ocean, it turns out that it takes about ten pounds of little fish to make a single pound of bigger fish (10%).  This is not a made-up number.  10% is largely accepted as the average Transfer Efficiency  (TE) between all levels of the food chain, whether you’re speaking of grass and cows, or hamburgers and people.  The 10% value has its origin in fisheries science, back when it was important to estimate the total amount of biomass supported by the oceans.  Fisheries Scientist Daniel Pauley reviewed 48 ecological studies and found the average TE to be 10%.  (See below, or here for references, where I discuss this topic without mentioning monkey-bumps).

So, when people say that it takes as much as five pounds of bait fish to make one pound of farmed (marine) fish, what they are really saying is that fish farming is twice as efficient as nature.  Say what?  Stop.  Let me say that again:  The Pew Ocean Report on Marine Aquaculture, which is highly critical of fish farming, states that the farming of marine finfish requires 4.13 pounds of bait fish for every pound of farmed fish.  That is a TE of 24%, more than twice the efficiency.  Think about it: farmed fish eat a pelleted diet that is specifically designed for their nutritional profile, they do not spend energy searching for food, and the pellets are bite-sized to minimize waste in feeding.  It’s.  Incredibly.  Efficient.

I’m not even going to wait for you to absorb that before I tell you that it gets even better.  Let’s go back to you, your hamburger, and the corn that was fed to that cow.  If you simply ate the corn, one pound of weight gain would only cost you 10 pounds of corn, rather than 100 pounds.  (Because you’re skipping the 90% loss incurred by the cow.  Stay with me.)  What does that say about farming higher level predatory fish?  If you could feed the little fish to the largest fish, you would see an increase in efficiency equal to a factor of 10.  Add that to the 24% TE we see in fish farming… carry the two… and we find that what takes nature 100 pounds of bait fish takes farmers 4.13 pounds.

As Neil Sims at Kona Blue has pointed out, the full cost of wild capture fisheries must also take into account the amount of fish tragically wasted as bycatch.  Accounting for bycatch makes the relative efficiency of farming compared to fishing increase again by at least a factor of 4.  Here, Neil has made the most conservative estimate to make his point.  The important thing to remember is that there is no bycatch in fish farming, and that means no dead fish thrown overboard, or turtles, bird, and dolphins stuck in fishing gear.

Why then, has there been this persistent message that hunting for large fish is somehow more efficient than farming?  Isn’t there a reas0n why we stopped hunting and gathering and began civilization with agriculture?

Let’s make two assumptions here: First, that seafood demand will continue to increase and capture fisheries will continue to decline.  Second, that short-lived, rapidly reproducing bait fish can always be managed more easily than large fish that take a long time to reach reproductive maturity.  In that case, farming is a very powerful conservation tool.  For every pound of farmed predatory fish, we leave at least 95  pounds of bait fish in the ocean to reproduce and function in the ocean ecosystem, with effectively no bycatch.

One last thing I will say, in light of Casson’s very informative and elegant blog on tigers and tuna, is that Tuna Ranching is Not Fish Farming.  Tuna ranching is the practice of holding and feeding wild fish until market conditions are favorable.  They do not produce any more tuna than what is already produced in nature.  These wild fish do not take a pelleted diet, and so the bait fish waste is considerable.  Having said that, I believe that the knowledge introduced by this industry will allow us to farm tuna from scratch.  That will, in turn, allow us to outlaw tuna ranching and possibly tuna fishing.

Ensenada tuna ranching

Hubbs-SeaWorld Research Institute uses the infrastructure of a bluefin tuna farm to support its yellowtail and hybrid striped bass farming operations in Ensenada.  It was necessary to move to Mexico because California still can’t make up its mind about aquaculture, and the state permitting process is mired in bureaucracy.

Recently we have been having conversations with chefs and consumers about farmed seafood—Aquaculture.  Unfortunately,  the general perception of this practice is a negative one.  Defined loosely aquaculture refers to the breeding, rearing, and harvesting of plants and animals in all types of water environments.  Currently aquaculture is the fastest growing form of food production in the world. It is also a significant source of protein for people in many countries, including the United States. Globally, nearly half the fish consumed by humans is produced by fish farms (noaa).  So why is it perceived as a 4 letter word here in the United States?

 The best way to examine this issue is through the world of salmon farming.  As the demand for salmon has essentially distended year after year, farms have been tapping waters everywhere.  From Canada to Chile, Tasmania and Scotland, salmon farming has lapped wild salmon in output capacity.  As is the case in any international commodity trade, there are good players, bad players, honest players and dishonest ones.  Certain farms have been guilty of stocking their ponds beyond reasonable density, perpetuating the outbreak of sea lice, and ultimately allowing their diseased salmon to escape and spread amongst the wild population.  At the same time however, there are salmon farmers who are producing a product that is healthy, respects the surrounding environment, and uses no chemicals as treatment for disease.  Should these farmers be punished as well, or should they be applauded for their efforts to make a positive change in an industry that clearly is the future?  By making all-inclusive statements like “farmed fish is bad” or “aquaculture is not the answer to overfishing”  are we further closing the door on an opportunity to exhibit our marine stewardship, and thus take the pressure off wild fish?

 It is a scientific guarantee that the supply of wild fish will NEVER meet the worldwide demand.  So what is the answer?  How can we continue to eat heart healthy fish at a rate of 2-3 times a week and not take into consideration alternatives once we have eaten our way through the ocean?  America is behind in the world of aquaculture.  As a result of the pessimism surrounding the notion of fish farming, and the millions of dollars spent painting farmed fish as evil, the government has been unable to establish the systems and regulations required to cultivate the aquaculture industry here in the United States.  Recently, Obama was attacked for trying to increase spending on the study of viable aquaculture practices.  Opponents critiqued that this would be the catalyst for the depletion of even more wild fish as they would be used in fish feed.  What do you think wild fish eat in the ocean….tofu?  No, they consumer the same  fish, but at an inefficient rate.  Farmed fish require less wild  feed per pound of output than wild species.

America needs to set the (or a) standard for sustainable fish farming.  As a scientifically rich nation, with forward thinking values committed to a sustainable platform, we can develop and homogenize a program that takes into consideration clean and healthy practices.  Unfortunately this is not happening, and instead underdeveloped countries with minimal care for the marine environment are farming in a dangerous manner, while we sit around and split hairs about fishery management.

Don’t misinterpret this post as unequivocally supporting farmed fish.  Quite the opposite rather.  There are farms in Asia, Scotland, Chili, Canada…that are farming irresponsibly.  They are producing in such a manner as to destroy communities, ecosystems and wild fish through irresponsible practices in an effort to maximize profits.  But don’t we do the same thing through commercial fishing.  How are we any more enlightened by trawling for wild shrimp, longlining for wild tuna, or allowing right whales to die in Maine lobster lines?  Why is one better than the other?  At what point is by-catch acceptable or for that matter, “sustainable”.  It’s not a black and white issue, and it never will be. It makes me really uncomfortable to say only eat green species, or don’t eat farmed fish.  Just because a species might be “green” doesn’t mean it’s not being over-fished. As consumers we can make a bigger difference by putting down the wallet cards and encouraging the consumption of responsibly farmed seafood here in the US.  The solution resides in the point at which effective fishery management meets responsible aquaculture. 

Below are some great products that are responsibly farmed and wonderful companies that recognize the need for responsible aquaculture:

cleanfish

http://www.kona-blue.com/

www.litchfieldfarms.net/

http://www.desertsweetshrimp.com/