|Sample Student Lesson
The Tuna/Dolphin Controversy
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Why would anyone get upset about a tuna sandwich? Yellowfin tuna live in warm ocean waters. These tuna often swim beneath groups of dolphins. Fishers have known this for years. No one knows why this is so. About 1960, the tuna/dolphin controversy began.
What happened in 1960? The American tuna industry developed a new way of fishing. The new method depends on the mysterious relationship between dolphins and tuna. This method is called "fishing on dolphin". This is a story about the way it works.
Dolphins are mammals. Like you, they breathe air with lungs. They must come to the surface often to breathe. Their surfacing and jumping makes them easy to spot.
The net is a mile long. It is 600 feet deep. How long is a mile? A mile is about as long as 12 city blocks. If you were to stand on top of a 60-story tall building and hold the top of the net, the bottom of it would reach the ground.
The two boats work together to complete the circle. The top of the net is kept in place by the cork line. The bottom is held down by the heavy lead line. The purse line is pulled in. It closes the bottom of the net the way a draw string closes a purse or bag. The tuna and the dolphins are caught.
Most of the net is quickly pulled aboard. A small section is left in the water. The section contains the tuna and the dolphins. The tuna move to a deep pocket of water. The pocket is near the side of the ship. The dolphins stay near the edge of the net. This is the most important time for the survival of the dolphins.
The skipper of Joan P. begins to "back down". The ship pulls the net out from under the dolphins. Most of the dolphins swim away.
Not everyone feels the same way about dolphins. For one, the government of Japan classifies dolphins as "harmful marine mammals". Some fishers treat the dolphins as such. And when the U.S. government passed laws to limit the dolphin kill, some tuna fishers left the country. In some other countries, they could fish as they pleased. Fishers from Mexico, Venezuela, and the European Community continued to kill dolphins as they fished.
Many people felt something needed to be done. One group of conservationists urged people to boycott yellowfin tuna. Boycott means "refuse to buy". Yellowfin tuna is sold as "light meat" tuna. The boycott tried to get tuna fishers to change the way they fish. Many people stopped buying the tuna. Some tuna fishers had trouble selling the tuna they caught.
New tuna fishing methods are being developed to protect dolphins. Now 95% of all tuna are caught without harming dolphins. Other kinds of tuna, the Albacore, skipjack, and bonito, are caught on hooks. Sports fishermen catch the yellowfin tuna without a purse seine net.
Even so, about 3,000 dolphins are still killed each year. The Earth Island Institute is working to stop the practice of "dolphin fishing" for tuna. This seems like a good idea. After all, no one wants to kill dolphins.
But as with many complex issues, things may not always be what they seem. Marine Mammal Biologist, Doug DeMaster works at the National Marine Mammal Laboratory. He has spent over ten years working on this problem. He agrees that the number of dolphins killed in the past was unacceptable. But, he and other scientists believe that the 3,000 dolphins killed each year is acceptable.
This all sounds good for dolphins. The move toward "dolphin safe" tuna has been successful. True enough, but this success comes with a real threat. The threat is to the ecosystem of which the dolphin is a part. Let's see how.
Dr. DeMaster says there are three ways people catch tuna in warm Pacific Ocean waters. "Dolphin fishing" is the way we've been looking at. "School fishing" is a second way. In this, tuna are surrounded in a way which harms few dolphins. The third way to catch tuna is called "log fishing". In this, the net surrounds all of the animals that gather near floating objects. Turtles, sharks, and other animals are caught along with the tuna.
At least some of the dolphins are not waiting for people to solve the problem. These dolphins allow themselves to be "rounded up". They are herded into an ideal position for capture. But as soon as the net is set out in the water things change. The dolphins scatter in all directions. They take the tuna with them.
The tuna/dolphin controversy is a difficult problem. Hopefully, fishers and conservationists will reach a good solution quickly. Whatever the final solution, both fishers and non-fishers need dolphins and tuna.
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