Friday, March 06, 2009

How much is a dolphin worth?

What would you trade to save a dolphin's life? A single shark seems like a pretty good deal. How about about 10 sharks? That's getting a bit pricey.

What about 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 endangered sea turtles? That's the bycatch cost associated with saving a single dolphin by moving to 'dolphin safe' tuna fishing practices. Dolphin safe tuna, it turns out, is an ecological disaster. It seems the only species it's better for is dolphins. The reason is the method used to find the tuna schools.
[A]fter a large group of tuna is located, a miles-across purse seine net is closed around them via a group of small boats associated with a large factory ship. It’s an effective way to catch large amounts of fish for not a lot of money.

This technique is pretty standard- the main variation lies in how the large group of tuna is located. There are basically three ways to do this.

  1. Get lucky and happen to stumble across a large group of tuna visible from the surface in the middle of an enormous ocean. Obviously, this isn’t terribly practical.

  2. Attract tuna using floating objects. Stay tuned, we’ll come back to #2.

  3. Follow dolphins, because dolphins in the Eastern Tropical Pacific are often associated with large schools of tuna. Dolphins are easy to follow because, unlike tuna, they have to come up for air.
For a long time, #3 was the most common way of catching tuna. The problem with this method was that by definition, dolphins are right there- and they get caught in the net as well.
Unfortunately the problem with #2 is that floating objects attract so much more than just tuna, resulting in the bycatch mentioned above. Dolphin-associated tuna schools, on the other hand, are primarily mature tuna.

Dolphin-safe tuna is even bad for the tuna. The 'small tuna' bycatch refers to pre-reproductive fish, removing them from the breeding pool and making tuna fishery even more unsustainable.

Of course changing the 'dolphin friendly' label to 'eco unfriendly' (or 'ONLY dolphin friendly) is probably never going to happen.

What's a dolphin worth to you?


Anonymous said...

Dolphins are far more intelligent than any of the other bycatch species mentioned. This is why it is far more important to save a dolphin than any of the other species. The dolphins represent the most likely species to exact their revenge upon fish eating humans. Keep them happy, and perhaps they will continue to let us coexist.

Anonymous said...

"Intelligent and friendly on rye bread with some mayonnaise."

Bayman said...

Personally I always look for the tuna-safe logo when I buy my dolphin.