Welcome to Pulse of the Planet’s Science Diaries, a glimpse at the world of science from the inside. Today we’re off the coast of Guatemala with Carl Safina, founder and president of the Blue Ocean Institute. He’s aboard a research ship that acts as a floating laboratory for scientists that study ocean life. One of their questions is why the area’s dolphin population hasn’t rebounded since the introduction of dolphin-safe tuna fishing methods. We join Carl on the bridge of the ship in conversation with researcher Lisa Balance.
CS: “We’re about, I would say, half a mile away, perhaps. And even without my binoculars up right now, I can see that there’s a big flock of birds, and I can see the splashes of the tuna ripping through the surface below them, and the fact that that it is a flock with different species of birds. You can just see from here different sizes and different colors of birds, but the ship is turned toward them, and we’re gonna be approaching soon. Okay. Tell me why is it that the dolphins have just suddenly started frothing the water and running very hard away from the ship?”
LB: “Well, they have learned to avoid ships that approach them in this area because this is where they get set on by the purse-seine fleet.”
The so-called purse-seine method of fishing corrals both dolphins and tuna in a net that is then drawn closed, like a purse, at the bottom. The dolphins are then allowed to escape the net before it is hauled on board.
LB: “Typically, a purse-seiner will come and lower speed boats, chase the dolphins, try to herd ’em into a tight ball, and then, they set the net around the dolphin school. They’ve learned that over the years, and so, they run away from ships in this part of the world.”
You can check out Carl Safina’s blog on pulseplanet.com. Pulse of the Planet’s Science Diaries are made possible by the National Science Foundation. I’m Jim Metzner.
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