Should you eat farmed Bluefin Tuna?
I recently had dinner with my family at an upscale Spanish tapas restaurant near where my parents live. This particular restaurant was known for their tuna dishes, which the waiter happily informed us were all exclusive made using bluefin tuna, the most exclusive of tuna.
Unfortunately, bluefin tuna is exclusive because it is overfished to the point that it is now an endangered species (Collette et al 2011), something my mom has heard me mumble under my breath many times.
My mom, quite the extrovert , assertively informed the waiter that we don’t eat bluefin tuna because it is heavily overfished — making it a food that should not be eaten by anyone, ever.
The waiter, slightly taken aback, then replied that the tuna being served was actually farmed, and although he doesn’t eat them, the restaurant says this makes them more sustainable to eat. This of course leads us to an important question — what is farmed tuna, and is it better than the wild-caught version?
The road to becoming endangered
Current international fishing regulations stipulate that every country has the exclusive right to catch and regulate any fish or other aquatic animal living within 200 miles of their coast. This is a regulation that largely developed due to competition over Atlantic cod fisheries during the 20th century (Kurlansky 1997). In practice, this makes it easy to create regulations that protect a species like redfish that lives exclusively along the coast. Redfish are an important commercial fish species, and like tuna were also once heavily overfished to the point of population collapse. However, since proper fishing regulations were put in place by the United States, the population has recovered and is now considered healthy and stable (Chao 2020).
Unlike Redfish, bluefin tuna live far from shore and migrate thousands of miles per year searching for food. They live nearly their entire lives past the 200-mile boundary where a single country could regulate the commercial catch for the species. For this reason, international treaties are required in order to regulate the commercial bluefin tuna catch. Many seafood producing countries do not want treaties that will prevent them from harvesting food from the open ocean. The goal is to gobble up as much of the pie before it is gone, and each country assumes that even if they choose not to participate others will, so the resource will still be depleted. No country will agree to regulate their own fishing fleet if they think others are taking more than their fair share. It is a modern example of the economist William Forster Lloyd’s tragedy of the commons, with and makes it extremely difficult to negotiate quotas that would actually protect bluefin tuna populations.
Even if treaties can be agreed to, they are almost impossible to enforce. Prosecuting a crime on the open ocean is difficult since evidence is easily dumped overboard and lost forever (Urbana 2019). Additionally, there is no police force that patrols the open ocean enforcing treaties, so enforcement is left to whichever country a fishing vessel is registered in. Oftentimes, fishing boats are registered in developing nations with minimal law enforcement ability (think Mongolia), even if the company and crew that runs the ship are based in a totally different country. This arrangement benefits both the country, due to the tens of thousands of dollars in registration fees they receive, and the company, since they get to pick and choose where they think there will be the least oversight (Urbana 2019). The arrangement also provides the perverse incentive for poor nations to intentionally avoid prosecuting vessels that break the law, since it can mean increased money coming in from registration fees. As a result of these difficulties with both enforcement and prosecution of illicit fishing on the high seas, it is estimated as much as 40% of all fish caught in some places are done so illegally (Agnew et al. 2009). As long as consumers will spend exurbanite sums of money for the chance to eat bluefin tuna, there will be fisherman willing to catch them, whether legally or illegally. This is why entrepreneurs have begun producing “farmed” tuna — to try to avoid the controversies of the wild caught product.
What actually is “farmed tuna”?
When most people think of animal farming, they probably imagine cows grazing in a field or chickens in cages laying eggs. Tuna farming is very different, and not just because it happens underwater. When tuna reproduce, they release millions of eggs that drift through the ocean currents before hatching into microscopic planktonic larva.
The early tuna life cycle is actually more like a butterfly than a mammal in that the larva do not even resemble a fish. Born without even eyes or a true spine , they have to undergo a metamorphosis over the first weeks of their life before we would even recognize them. During this larval stage, they eat other tiny microscopic plankton like copepods to rapidly grow and morph into juvenile fish, which is the life stage after larva.
Finding a way to replicate the needs of these larval tuna has thus far proved impossible in a farm or laboratory setting. Although baby tuna has been hatched from eggs many times, no researcher has successfully figured out how to get tuna through their larval stage and survive to be fully metamorphosized juveniles (Charles 2014). But if aquaculturists can’t crack the code and successfully grow tuna from eggs into fish, how can they claim to be “farming” them?
In short? They cheat by catching juvenile fish. “Farmers” go out into the ocean and catch juvenile bluefin tuna and pack them into nets pens, then feed them until they grow large enough to be sold at market. As seafood journalist Paul Greenberg appropriately notes, “this represents an overall loss of wild bluefin, not a gain” (Greenberg 2010), since tuna are being removed from the ocean before they are ever able to reproduce.
Solving this purely technical issue of getting baby tuna through their larval development would not, however, make bluefin tuna farming sustainable. Tuna are large carnivores, similar in many ways to a tiger (Collette et al 2011). In order to obtain one pound of bluefin tuna muscle growth (the part that we eat), tuna need to be fed roughly 15–20 pounds of other fish meat (Greenberg 2010). Comparatively, salmon require only 2 pounds of meat from other fish to produce 1 pound of meat for sale, while algae-eating fish such as tilapia (as well as mollusks like oysters or scallops) require no fish derived protein to grow. An ideal animal for farming needs to be both easy and cost effective to feed. This is why we farm herbivores like cows and sheep that eat grass and are happy around people, and not tigers that are large carnivorous and eat cows and sheep. The math for farming large carnivores will never add up, whether on land or in the ocean.
Is Farmed Bluefin Tuna Actually Sustainable? And Should You Be Eating it?
Not only does farmed tuna remove otherwise wild tuna from the environment and prevent them from breeding, it also requires an enormous input of other fish to produce the final product. Farmed bluefin tuna somehow manages to be even worse than the wild caught version of the fish, a feat that is as sad as it is impressive.
There is no such thing as sustainable bluefin tuna, and I would not recommend holding your breath waiting for someone to produce it (Greenburg 2010, Charles 2014). If you see bluefin tuna on a menu, just don’t eat it. Even better, tell the restaurant why you don’t want the bluefin tuna on the menu. Right now, bluefin tuna is seen as a prestigious item used to lure diners in by demonstrating how luxurious the menu is. If people start complaining to the chef that they don’t want to see bluefin tuna on the menu this will change. Restaurants are low margin businesses, and even losing a small number of customers can lead to bankruptcy. If selling bluefin tuna makes a restaurant into a pariah to consumers, it will quickly disappear from menus.
If restaurants are unwilling to pay the high prices to purchase bluefin tuna, fishermen will stop catching them. It will take time, but if people stop catching bluefin tuna the population will eventually recover. If we want to continue to eat wild fish we need to care about where our fish comes from. The ocean is not boundless, and if we do not actively fight to keep wild fish populations healthy, one day there will be no fish left.
References
Agnew DJ, Pearce J, Pramod G, Peatman T, Watson R, Beddington JR, Pitcher TJ (2009). Estimating the Worldwide Extent of Illegal Fishing. PLoS One 4(2):e4570.
Charles D (2014). Farming the bluefin tuna, tiger of the ocean, is not without a price. National Public Radio, Morning Edition. https://www.npr.org/sections/thesalt/2014/07/30/336339179/farming-the-bluefin-tuna-tiger-of-the-ocean-is-not-without-a-price. Accessed October 5, 2022.
Chao L (2020). Sciaenops ocellatus. The IUCN Red List of Threatened Species. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T193270A82667516.en. Accessed on 05 October 2022.
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Greenberg P (2010). Four Fish: The future of the last wild seafood. New York, NY, Penguin Books.
Kurlansky M (1997). Cod: A biography of the fish that changed the world. New York, NY, Penguin Books.
Myers SL, Chang A, Watkins D, Fu C (2022). How China targets the global fish supply. New York Times. https://www.nytimes.com/2022/09/27/briefing/china-fishing-galapagos.html. Accessed October 5, 2022.
Urbina I (2019). The Outlaw Ocean: Journeys across the last untamed frontier. New York, NY, Penguin Books.
