Unintended Consequences in Tuna Fishing

In the 1980’s, fishermen trawling for tuna killed tens of thousands of dolphins each year, scooping them up as “bycatch” in their nets. A public backlash spurred development of a “dolphin safe” fishing method — which, while great for dolphins, turns out to be a catastrophe for sharks, sea turtles, mahi-mahi, and other sea creatures, many of them endangered. Dolphin-safe fishing is also a less ecologically sustainable way to harvest tuna stocks. The Southern Fried Science blog has the grisly details, showing that eco-reform, like everything else, is beholden to the law of unintended consequences. [%comments]


In fairness, I think part of the argument is that dolphins are so intelligent that they have a right to not be killed. That right doesn't apply to sharks or sea turtles, so advocates of dolphin-friendly fishing methods might not be all that concerned about those particular consequences -- unintended or not.


paraphrased: "saving 1 dolphin equals the death of 382 mahi-mahi, 188 wahoo, 82 yellowtail and other large fish, 27 sharks, and almost 1,200 small fish"

it has always struck me that "dolphin-free" tuna was very artificial anyway. why not "turtle-free" tuna? those turtles are at least as cute as the dolphins...


There should be a "public backlash" for overfishing tuna. When already low tuna stocks becomes depleted, you'll be signing the reverse song of the law of unintended consequences.


There should be a public backlash over animal rights activists grandstanding when the "cute" animals are involved. We're at the top of the food chain and I, for one, prefer to stay there.

I'm having tuna for lunch today.


Peter - only some species


the market is not so safe for dolphins- check out the documentary - "the Cove"

Hah! This is a classic example of opportunity costs, the most important part of someone's decision making process. Reading the first sentence you can assume that the method fishers used was inefficient. Then as you keep reading you might be relieved when they developed a “dolphin safe” method. Now it results that dolphins are safe, but what about sharks, turtles and mahi-mahis and other similar bycatch creatures that aren't? There's a huge opportunity cost for both ways of fishing, both will kill bycatch animals, but which method is more efficient? It's either dolphins or sharks and the other similar creatures or not fish tuna at all. I think the government should interfere by thinking at the margin and establish rules. They can develop a new way of tuna fishing without harming other animals, and if they can't, keep the same method (only if the profit gained from tuna exceeds the cost of killing the bycatch animals) or not fish tuna (only if the benefit of not killing the bycatch animals exceeds the profit gained from tuna). I only warn them to think rationally at the margin but all the decisions will have costs, choose the one they think has the least cost, where the benefits exceed the costs.



No one realized the irony in making the hunting of one type of animal safe for a different type of animal? Obviously, you'd rather not cause the needless death of an animal. If the tuna will be eaten, that is useful. If the dolphin dies and discarded, that is needless and ideally would be avoided. Yet, if more animals are dying as a result, well, we haven't really done anything to improve things.


This seems like a fair argument in the defense of not only dolphins but also any other sea creature. The world, as it is, is suffering from a condition called the "tragedy of the commons" which basically means we are taking to much from places that don't belong to use, but belong to everyone. This is tragedy that in time will affect everyone, and most definitely have an impact on the economy. If too much tuna is fished one year, then they wont be able to reproduce enough to satisfy everyone's needs. This usually happens when people start getting greedy, and try to take more than the competition. In a way it might seem as if these new fishing methods, which prevent the dolphins of being caught, but have the opportunity cost of catching less tuna, might be better, than just catching as much as you can of everything. This would cause the the price of the tuna to go up, but it would prevent a tragedy of the commons, and if a tragedy of the commons were to occur, then wouldn't this as well make the price of the tuna go up? I mean, there is less tuna, giving the people who sell tuna scarcity power, basically regulating the price at what they feel is correct.
On the other hand, we have the problem of other sea creatures in extinction getting caught as well, in this new way of fishing. This is also a problem because, first of all no animal should be in extinction, no matter how useless they might be, and second of all if one sea creature goes extinct, then it will affect the way that the whole marine cycle works, because you are taking out a component of it. The best thing to do in this case to devise a way in which tuna, and only tuna are caught. Maybe by using something only tuna is attracted to as bait, or isolating the tuna, and putting them on breading grounds (which is done with other types of fishes like salmon).
In conclusion the opportunity cost regular tuna fishing is also fishing dolphins, which are in extinction, and creating a tragedy of the commons. In the other hand we can use the dolphin-free fishing method, but make sea creatures go extinct disrupting the marine life cycle.



Isn't the lesson that not accounting adequately for externalities creates a backlash that creates distortions?

It's not that the dolphin free initiative was at the behest of eco freaks that valued dolphins above the other species you mentioned. Rather, the outcry was against the impact and waste of the existing harvesting techniques. "Dolphins" in a way was simply a metaphor for the unaccounted environmental impact -- costs imposed on us all that were not borne by the harvesters.

I'm not sure that your argument is that any attempt to address externalities will result in absurd distortions and area waste of time? Seems a tad cynical. Note that the comments seem to have stirred up the usual cynical anti eco freak humbuggery.

Johnny E

Mahi-Mahi are too valuable to be considered by-catch.


Agh the worst part about it is I hate dolphins!

Are there any dolphin-lethal brands I can buy?

Also @11, not unless they're separated, processed differently, and sold as Mahi Mahi.

Randall Arauz

The problem is tuna purse seine fishing. It isn't sustainable, be sharks, turtles, dolphins, and not even the tuna. Take a pick? I say, industrial tuna purse seiners have got to go...and replaced by the old pole method. The problem is that you have the industry, with all their infrastructure and political and economic power, pushing to keep the status quo, organized in Tuna Commissions all over the globe, where they are represented IN the local governments. The sad thing, is that this doesn't seem like it will stop, precisely because of this political arrangement, until of course the tuna are depleted and the industry collapses, dragging the turtles, sharks and dolphins to extinction. This has already happened to several species of tuna, and its happening to the yellow fin tuna in the Eastern Pacific too.


Dolphins: cute, great personality, very photogenic.
Other species: not so much.

Dolphins: Win!