Dolphin-safe tuna: conservation success story or ecological disaster?

I used to feel warm and fuzzy inside when I saw the dolphin-safe logo on my tuna. I felt like a decision I made was helping the environment- like I was making a difference.


The commonly believed narrative about dolphin-safe tuna goes something like this: Lots of dolphins were being killed by tuna fishermen, outraged environmentalists led a massive PR campaign, legions of adorable children wrote to their elected officials, elected officials changed the rules to protect dolphins, and everything is better now. Hooray, we saved an innocent species and helped the environment!

That narrative is a great story. It shows that if a few people who care can convince others that their cause is just, there’s no limit to what we can accomplish. It’s inspiring. Too bad it’s not really true. As it turns out, we made things worse- a LOT worse.

Before we get into specifics, a little background  is in order. The tuna fishery, one of the world’s largest, employs tens of thousands of people and provides millions with a cheap source of protein. It can be difficult for people who have never seen it in action to appreciate the scale of modern commercial fisheries. Commercial fishermen aren’t out on the high seas with handheld rods and reels catching one fish at a time. The nets that tuna fishermen use, which are called purse seines, are miles long. With a net that size, it’s pretty much impossible to catch only tuna. Those nets also catch anything that happens to be swimming near the tuna. These unfortunate animals, killed for being in the wrong place at the wrong time, are called bycatch.

The diagram below shows how tuna purse seine nets work. Once a school of tuna is located (we’ll discuss how that happens a little later), a series of support ships help to deploy the giant purse seine from the main factory ship. The bottom of the net is drawn closed, and the contents of the net (tuna and bycatch) are brought onto the main factory ship.

Figure from "An introduction to monitoring, control and surveillance systems for capture fisheries", available at

Once the tuna are located, the method for catching them is just as I’ve described above. The differences, and the source of the controversy with tuna fishing, comes from how the tuna are located in the first place.

There are three ways that tuna schools can be located. The first is to search for them directly using surface ships and small aircraft, which is inefficient, time-consuming, and not always effective (you can’t see tuna from the surface if they’re deep enough or if weather conditions aren’t ideal). The second is to attract tuna using floating objects, which we’ll discuss in more detail shortly. The third is to follow dolphins- for unknown reasons, dolphins in the Eastern Tropical Pacific are often found associated with schools of large tuna.

Now that we have some background, let’s return to the “environmentalists saved dolphins from fishermen” narrative. The first part of the narrative is  mostly true. Because finding dolphin-associated schools of tuna was extremely easy (unlike tuna, dolphins have to return to the surface where they are easy to  spot), it was the preferred method for decades. The Eastern Tropical Pacific Tuna Fishery had a high rate of dolphin bycatch. According to NOAA’s Southwest Fisheries Service Center, an estimated six million dolphins were killed during the forty or so years that purse seining around dolphin-associated tuna schools took place. That’s approximately 150,000 dolphins per year, which is by far the largest cetacean bycatch of any fishery in history. However, it is important to note that mortality from being tuna bycatch did not mean that dolphins were endangered. The two primary species involved are spinner dolphins (data deficient) and spotted dolphins (least concern).

The second part of the narrative is also true. A massive PR campaign led by the Earth Island Institute resulted in making it illegal to sell tuna caught from dolphin-associated schools in the United States. Dolphin-safe tuna was born.

Now that fishermen could no longer use what was previously the most common method for catching tuna, they needed to change strategies. They turned to using floating objects (sometimes called FAD’s or fish aggregating devices) to attract tuna to a known location. One of the strangest known behaviors exhibited by open-ocean animals is their tendency to aggregate around any solid object that floats. This might have something to do with the fact that many open-ocean animals go their entire lives without seeing any sort of hard surface. This method is extremely effective for aggregating tuna, but it also aggregates many other species. Setting a purse seine around a dolphin-associated tuna school results in catching primarily large adult tuna (the target size because they have more meat per unit effort and because they have reproduced already) and dolphins (which are not endangered) . Setting a purse seine around a floating object results in all sorts of bycatch, including endangered sea turtles, open ocean shark species which are already in serious trouble, and high numbers of small tuna (which have not yet reproduced).

Table from Hall 1998. "Log" = floating object, "school" = tuna found by plane or boat, "dolphin" = dolphin associated

A simple glance at the table above shows that while dolphins bycatch goes down, every other studied species (except “unidentified bony fishes”, “other sailfishes”, and marlins) has much higher bycatch rates in “floating object” tuna fishing than in “dolphin associated” tuna fishing. In other words, while better for dolphins, “dolphin-safe” tuna is disastrous for almost everything else. For open-ocean sharks, floating object fishing is orders of magnitude worse than dolphin-associated fishing. In some cases, such as mahi-mahi, wahoo, and triggerfish, the new method is exponentially worse.

Large numbers of these already threatened sharks are killed by "dolphin-safe" tuna fishing

If you do the math on this (and you don’t have to because the Environmental Justice Foundation already did), you find that one saved dolphin costs 25,824 small tuna, 382 mahi-mahi, 188 wahoo, 82 yellowtail and other large fish, 27 sharks and rays, 1 billfish, 1,193 triggerfish and other small fish, and 0.06 sea turtles.

You and I can argue about the relative value of dolphins vs. triggerfish all day, but the important take-home message here is that we are protecting animals that are not endangered at the expense of dozens of other species, and some of those other species are endangered.

Last summer, I went on NPR’s “The Pat Morrison Show” to discuss this issue with a representative from the Earth Island Institute, the organization most responsible for dolphin-safe tuna policies. I had expected him to acknowledge that the bycatch was a problem, but that it was still important to protect dolphins because they’re intelligent mammals (or something like that). Instead, he argued that there was no bycatch of endangered species taking place under dolphin safe tuna policies, and he accused me of perpetuating the propaganda of evil fishermen who “just want to kill dolphins”. Yikes. His ridiculous rants (and his subsequent refusal to continue the discussion on Southern Fried Science) cost the Earth Island Institute my respect, as well as that of many who heard the interview.

The fight to save the oceans is a long and difficult one, and I don’t know for sure how we’re going to win. I do know, however, that we will never win by making up lies about the other side or refusing to acknowledge when we make mistakes. Let us be honest with ourselves and with the world- the push for dolphin-safe tuna was a mistake. It was a well intentioned mistake, but it was a big mistake with disastrous consequences.

What can we do? The first thing that popped into your head was probably “ban tuna fishing”, which is a more politically correct way of saying “make it impossible for the world’s poor to have healthy balanced diets”. It’s just not feasible to ban purse seine fishing. If you’re interested in helping by “voting with your wallet”, you can support sustainably-caught tuna, which is caught with a rod and reel and has almost no bycatch, but this method makes tuna so much more expensive that it’s not a large-scale solution.

A conscious choice to go back to a previously-banned fishing method that kills large numbers of charismatic animals puts a bad taste in my mouth, but the fact is that fishing for dolphin-associated schools of tuna catches primarily non-endangered dolphins and adult tuna. Dolphin-safe tuna fishing is killing dozens of species, many of whom are endangered, and threatening the integrity of entire ecosystems. The old way may be the better of two bad choices.

This is a modified repost of “the ecological disaster that is dolphin-safe tuna” from the old site. That award-winning post and it’s over 200 comments can be seen here.


Au, DW (1991). Polyspecific nature of tuna schools: Shark, dolphin, and seabird associates Fishery Bulletin

Barker, M., & Schluessel, V. (2005). Managing global shark fisheries: suggestions for prioritizing management strategies Aquatic Conservation: Marine and Freshwater Ecosystems, 15 (4), 325-347 DOI: 10.1002/aqc.660

Girard, C. (2004). FAD: Fish Aggregating Device or Fish Attracting Device? A new analysis of yellowfin tuna movements around floating objects Animal Behaviour, 67 (2), 319-326 DOI: 10.1016/j.anbehav.2003.07.007

Hall, M. (1998). An ecological view of the tuna-dolphin problem: Impacts and trade-offs Reviews in Fish Biology and Fisheries, 1-34

Joseph, J. (1994). The tuna-dolphin controversy in the eastern pacific ocean: Biological, economic, and political impacts Ocean Development & International Law, 25 (1), 1-30 DOI: 10.1080/00908329409546023

LEWISON, R., CROWDER, L., READ, A., & FREEMAN, S. (2004). Understanding impacts of fisheries bycatch on marine megafauna Trends in Ecology & Evolution, 19 (11), 598-604 DOI: 10.1016/j.tree.2004.09.004


  1. Betul · July 26, 2010

    Thank you for this post. I agree with you that something has to be done before all sea animals go extinct, to stop this madness. As for my part, no more tuna sandwich for me.

    On another note, you can find ‘byproduct’-(dolphin, shark etc) skin purses and wallets in Hawaii. When I reacted to it, the shop-owner (not kindly) asked me to leave his store and said ‘they are already dead, this way their skin is not wasted’. I find it hard to believe that it is all good intentions, if there is a buyer even for the byproduct then why should you stop creating massive byproducts? Thanks again.

  2. fiona maskell · July 26, 2010

    Thank you for this report – but why do you say that banning tuna fishing will deprive the poor of a balanced diet? Sylvia Earle says … is that not realistic? I would rtaher see other forms of protein being made available (legumes for example) and leave the tuna alone at least until they can recover. And this business of ‘adult fish have already bred’ … where does that come from? is not new research showing that it is the mature individuals that produce the young?
    oh how frustrating and tragically full of self-interest is any talk of the sea!

    • WhySharksMatter · July 26, 2010

      “is not new research showing that it is the mature individuals that produce the young?”

      A general rule of sustainable fishing is that you don’t want to harvest a fish until after it has reproduced. That doesn’t mean that it wouldn’t have continued to reproduce if didn’t harvest it.

      “Sylvia Earle says … is that not realistic?”

      I get very uncomfortable whenever we start telling desperately poor people who have known starvation what they cannot eat.

    • Southern Fried Scientist · July 26, 2010

      People tend to forget that there are dozens of Pacific nations with absolutely no arable land that rely almost entirely on fisheries for their food supply.

    • Doris · August 7, 2010

      This is one reason why we need to seriously address human overpopulation instead of defending our “right” to exploit every other species on earth. If there are countries where the human population is unsustainable without plundering the surrounding oceans, those countries are biologically overpopulated. Of course, I’m not talking about forced sterilization, monetary incentives or other human rights violations. We have to address the issue humanely through public education, which includes educating our governments.

  3. Chuck · July 26, 2010

    I’m glad you updated this. I think everyone needs to read about this subject and how cute animal bias actually screws us all. Now we just need to get someone to market “dolphin unsafe” tuna…

    • Sam · July 26, 2010

      “Dolphin unsafe” tuna is actually illegal in the U.S. (and probably other countries). There was a big bru-ha-ha with Mexico and the WTO at first. U.S. policy on that probably won’t change because of that case.

  4. Patric Douglas · July 26, 2010

    Thanks for the article David. This is a classic example of legislation w/o enforcement. Looks good on paper, but is it effective?

    I would direct you to the fisheries law saving marlin in the USA. Longliners are prohibited from taking marlin.

    What happens?

    They still take marlin, but instead of processing a dead 1500lb animal it is cut loose and sunk by cutting its swim bladder.

    Effective? No. But try debating that with the several NGO’s who fought hard to win this law. They say they saved the marlin, I say they wasted their time.

  5. becca · July 26, 2010

    I’m kind of creeped out by the argument that any process that results in mahi mahi as ‘bycatch’ that gets thrown out rather then eaten is necessary for feeding the world’s poor. We have to fix fishery fishing to make it more sustainable *anyway*. Is dolphin unsafe tuna fishing better than dolphin safe? Perhaps. But that doesn’t mean this industry isn’t shouting out for reform. I just hope somebody *thinks* about the consequences next time.

    • Southern Fried Scientist · July 26, 2010

      I think you may have misunderstood Dave’s point – not all tuna fishing methods are equal. Pole-and-line is better than long-line is better than dolphin-set purse seine (maybe) is better than FAD-set purse seine. But a straight up ban on all tuna fishing hurts the pole-and-line crowd as much as the FAD-set seiner and precludes any industry reform.

  6. Alan Dove · July 27, 2010

    Is all of that bycatch really being thrown away? Mahi-mahi is delicious, and I would think some of the others could be put to good use as well.

    • WhySharksMatter · July 27, 2010

      Fishermen often only have a permit to land one species. If purse seiners could sell all of their bycatch, it would put a lot of people who target those species out of business- small boats can never hope to compete with miles-long nets.

    • Chuck · July 27, 2010

      At the same time, that is one of the downfalls of species specific management strategies. You run into situations where perfectly fine fish are tossed out (usually already dead from gear-related trauma) because they’re out of season or the fishery is closed or that particular fisherman isn’t permitted for that species. Those fish are still dead and removed from the ecosystem. It’s a tough balancing act, and unfortunately it’s about the best (or more accurately least worst) way fisheries managers have been able to work it so far.

  7. Paul Sharp · July 27, 2010

    Really, all Tuna fishing should be done the old way, with fishing poles. My father skippered a Tuna boat that pole fished during the fifties. He predicted  that trawling, long-lining and purse-seine fishing was going to destroy our oceans.
    A return to pole fishing would increase employment while maintaining a sustainable fishing practice with almost no bycatch.

    • WhySharksMatter · July 27, 2010

      Yes, but it’s also a LOT more expensive per pound of fish.

    • Christophe · July 28, 2010

      That’s maybe the price to pay for the oceans perenity.
      As Paul said, Industrial fisheries do not feed the world, just the the greed.

    • Fraser H · August 7, 2010

      The Solomon Taiyo fleet used to be primarily (if not exclusively) pole and line. As of last year I believe it is now long-lining – just not economically viable to pole and line, although when it was set up with the aid of donor money, it was.

  8. Paul Sharp · July 27, 2010

    On the subject of depriving poor people of cheap protien, the industrial Tuna fishery is doing this. They fish the oceans of poor nations and ship the catch to the affluent nations in Europe, North America and Asia. The Tuna industry is not a fishery that feeds the poor.

  9. RoyalsWithCheese · July 28, 2010

    That I was not aware of. Good old ocean, out of site out of mind. Every problem facing mankind goes back to the same thing, over population by humans of our wonderful planet. Yet this is not a topic any politicion will go near. I love my scuba and hate the way fisherman rape our seas. As for the poor, grow some beans and stop breeding. We need to stop interferring with natural selection.

    • WhySharksMatter · July 29, 2010

      “As for the poor, grow some beans and stop breeding.”

      Is that a serious suggestion? See Andrew’s above comment:

      “People tend to forget that there are dozens of Pacific nations with absolutely no arable land that rely almost entirely on fisheries for their food supply.”

  10. BronwynInAfrica · July 29, 2010

    This was a real eye-opener for me! I was feeling a bit bad that I couldn’t find ‘dolphin-safe’ tuna here… but not any more!

    I’m going to share this with some colleagues who are working hard on reforming the Indian Ocean Tuna Commission. We’re really concerned with bycatch, but also the issues of who benefits (as mentioned by one of the comments). Right now Kenya, Tanzania, and Mozambique (among other West Indian Ocean, WIO, countries) sell the rights to fish this multi-million dollar ground to European and Asian boats for a pittance. Its been estimated that the fishing industry COULD (but currently doesn’t) bring more revenue than the tourism industry in these Safari-centric nations without increasing catch, just reforming laws and encouraging local boats. Of course with sustainability in mind. It’ll be interesting to see the methodologies discussed!

    Since I’m living here in East Afica, when I buy my tin of tuna (packed in Thailand, distributed through Dubai, likely sourced in WIO) that does NOT say ‘Dolphin safe’, what is the likeliest methodology used for catching it?

    Maybe I should just stick to the nice fresh tunas I can run down to the Masasani fish market and buy that were line caught by a man on a little sailing dhow 😉 (of course I have to be careful that it didn’t come from a dynamite fisherman – who target tuna and mahi mahi here rather than reef fish – but that’s another story)

    • WhySharksMatter · July 29, 2010

      It’s hard to say how your tuna was caught. It could really be anything. It may even still be floating-object schools.

  11. Mike Lisieski · August 3, 2010

    I didn’t read all of the many comments here, so forgive me if this has been said:

    What is permissible for deperately poor people to eat to avoid death and disease has little bearing on what better-off people who have a lot of options should choose to eat. Nobody who has the resources to be commenting on this post eats tuna because it is literally the only protein source available to them. If this were about telling starving people not to eat tuna, it wouldn’t be an issue – but it’s not. It is, by and large, about asking people to grab a different can off of the grocery store shelf. The argument on the behalf of the world’s need is irrelevant and misleading in this case, because we’re not actually talking about the actions of people who are forced to eat tuna, but the actions of the much larger group of people who choose it over other foods.

    Even if it were a valid argument, it’s not economically sound. As far as global staple food prices go, soybeans stand at about $0.10-$0.15 per pound whereas tuna fetches at least $0.40 per pound (for whole fish, which is processed down to some fraction of its original weight.) If what we’re worried about is food for poor people, it’s odd that we’d support the use of a relatively more expensive protein source vs. relatively cheaper ones. (I may be somewhat inaccurate here because these are export prices to presumably corporate buyers and may not reflect local prices, but I take them to be indicative of the relative cost of each commodity in general.)

    The way to improve the nutritional lot of desperately poor nations is not to allow large-scale food production operations sponsored by companies from wealthy countries strip their traditional food source from them (as is the case with commercial fishing and farming, which has participated in the pseudocolonization of large portions of the developing world,) but rather to prevent this so that they can continue to use these resources locally. The large scale tuna-fishing operations that we’re discussing only exist because it is profitable to ship tuna to the huge populations of industrialized nations, who (generally) have abundant food choices, comparatively. If everybody who could afford to buy another protein source did, the catch would be sustainable, and it wouldn’t be a debate at all.

    From a practical perspective, we’d never be able to ban tuna fishing, even if we decided it was a good idea (as a vegan, this is a hard concession to make, but I think it’s necessary.) The industry clearly needs some sort of reform, and as long as we are going to harvest ridiculously unsustainable amounts of tuna, we should avoid killing as many other species as possible in the process, even if it means killing dolphins (which everybody seems to like, for some reason.) When we see the consequences of our actions, however, we should not say “it was for the poor people!” when we really mean something much less charitable like “tuna tastes good and makes a quick lunch, and I’d rather eat it than something else, even if it has some bad consequences.”

    Whew. Good post, by the way. I learned a lot.

    • Fraser H · August 7, 2010

      It’s an interesting argument. From a purely economic point you may be right. From a social and cultural standpoint, not to mention logistical standpoint, I see nothing but problems. There are often social status involved in what you eat and what you are seen to eat – that is a massive hurdle to overcome. Logistically – well, we need to find arable land to increase the production of legumes enormously, then have to transport to where they are needed (and if you include all the transport costs to small island developing nations in the pacific it may start to approach tuna prices in those nations – do you know if the volumes are comparable?). In island PNG and Solomons in my experience canned tuna is in fact a staple part of the diet, and gives a fair proportion of the populace their protein (something like 2-4 meals a week per household – it’s been a while since I looked at the survey results where the question was asked, and no longer have access).

      If fish is required as part of a diet, personally I would much rather have burgeoning coastal populations looking to tuna, rather than pillaging the nearby coral reefs.

  12. Katya · August 3, 2010

    This is a fair and balanced (and a tad daring) post. Captivating writing too. Kudos! I’ve some colleagues working with UNFSA and ICCAT who will undoubtably be interested. Keep up the good fight 🙂

    • WhySharksMatter · August 4, 2010

      I’m glad that you liked it, Katya. Please let me know what your ICCAT and UNFSA friends think (or have them comment here). I haven’t published it other than on the blog and in the marine conservation magazine “Beyond Blue”- it’s not really publishable in a scientific journal.

  13. Katya · August 3, 2010

    p.s. have you published this?

  14. Chisa · August 4, 2010

    Tuna populations are dwindling as fast or faster than any other species (except maybe sharks)…why is there even a discussion of ‘going back’ to ‘porpoise fishing’? Stop the commercial fishing of tuna…that is what we MUST do. In fact, we should stop ALL commercial fishing where there is significant bycatch (that’s pretty much ALL commercial fishing, period).

    I’m pretty sure when Sylvia Earle says to stop eating fish – that is a message to all of us who have another alternative. I’m sure the desperately poor could keep fishing and as long as huge commercial operations stopped, we would help the ocean and its fisheries tremendously.

  15. Patrick · August 5, 2010

    I guess the only way to save our oceans is by banning the industrial fishery for a while and make proper regulations for the time after that. All traditional fishery would be still aloud what would feed all ocean nations as well.

    Really nice posts up there, but the problem discussed is to isolated and should go further.

    Well done, thanks for the input

  16. Mariah Boyle · August 10, 2010

    Hi David,

    Great blog on tuna. I love how you cite so much science in your blogs.

    It is true that the Fish Aggregating Devices (FADs) when used with purse seines are unsustainable. The MBA Seafood Watch card ranks all tuna fisheries that use FADs with a red ranking, as they are unsustainable due to their bycatch as you noted. However, purse seines that don’t use FADs can be yellow or even green depending on the species and ocean. I don’t know for a fact that dolphin-safe tuna always uses FAD purse seines, but to be honest a lot of the industry does, as well as longlines, which aren’t much better. IUU (illegal, unregulated, and unreported) fishing is also a problem with the cosmopolitan tunas, but the creation of the ISSF ( gives me hope. They are a global partnership whose mission is to undertake science-based initiatives for the long-term conservation and sustainable use of tuna stocks, reducing bycatch and promoting ecosystem health.

    Until then, it is best to buy tuna from groups like Wild Planet and Henry and Lisa’s that note the catch method and region of catch on their websites and packages, as many canned tuna products fall into the unsustainable red-ranked category per the Monterey Bay Aquarium. However, tuna fishery improvement projects are gaining momentum, so hopefully soon even more tuna will be sustainable.

    To look for other progressive companies making commitments to seafood sustainability, check out our partners at

    Keep up the great blogging!

  17. Ecological · August 18, 2010

    So basically, the fisherman were using a natural method to search for tuna and if the dolphins got caught, too bad for them? I guess while I can imagine people being offended that they’re eating dolphin, I’d say unless they were catching a loT of dolphin, they weren’t endangered in the first place.

    As for the Earth Island Institute, I honestly thought that was extremely unprofessional, and ATM, if other endangered species are going because of these policies…I agree the old way is the lesser of two evils

  18. Anna Laisheva · September 12, 2010

    Dear WhySharksMatter,
    I’m working on a project in my biology class, and i was wondering how much money is being spent on this project? And also is this project successful so far? Please reply a.s.a.p.
    Thank you,
    Anna Laisheva

    • WhySharksMatter · September 14, 2010

      I’d be happy to help, but I don’t understand your question. What project are you talking about?

  19. melissa · September 19, 2010

    Great post! You’ve brought up a lot of important bycatch issues associated with the tuna fishery. I’m all for reducing the massive amounts of bycatch, and if it were this simple would be with you on just losing non-endangered dolphins over many other species, including endangered ones. But either I’m misunderstanding something here, or you’ve set up a false dichotomy pitting a return to dolphin sets vs continuing bycatch from FAD sets and long-lines. Dolphin sets are still happening. They make up 1/3 (~10,000 per year) of sets on tuna in the ETP. The only tuna species that dolphin sets bring in are yellowtail. Cheap canned tuna is made up of the smaller species like skipjack and albacore which are only very occasionally found around dolphins. So while I agree that the dolphin safe label may “trick” people by hiding information about all the other dangers of tuna fishing, I don’t see how upping the quotas on dolphin deaths and thereby number of sets on dolphins will do anything to bring in other species of tuna that FADs and long-lines do better at. That will just mean more dolphins are dying in addition to all the deaths of sharks, turtles, and smaller fish. And several populations of dolphin species in the ETP have had near or below 0 growth rates since their depletion in the 1970’s, so while they are not endangered, increased death rates could bring them there, particularly considering net deaths are highest among neonates and juveniles. So I guess we’ll have to work on another option.

  20. Bobbi Higgins · October 16, 2010

    I would like to have a magaize send to me so I can help safe all wild animals. My mail address is 108 W. Hamtramck St. Apt. D Mount Vernon, Ohio 43050

  21. Annette Godbout · November 29, 2010

    The proportion of animals now in danger compared to the number of dolphins being saved is unacceptable. Although, yes, I consider myself a dolphin lover I do not believe all of the other species should be jeopardized in order to focus on merely one animal. Although I realize it is easier said that done, more research should be done on alternative methods of netting/fishing techniques.

  22. B · January 27, 2011

    Are there any proposals that include taxing fish varying amounts depending on the fishing method used? This would put transfer the environmental cost of different techniques to the consumer, as opposed to the entire globe.
    An additional benefit is that this could lead to developing more bycatch-friendly fishing methods, since this would leave to a price advantage in the market place.
    I think bans are like hammers, when what we need are scalpels.

Comments are closed.