Andrew Revkin has an excellent post on the declining ocean stocks of the Northern Bluefin Tuna, mainly due to the depletion caused by overfishing.
I think, sadly, environmentalists are really late to the game in this regard. Many species of ocean are well on their way to extinction if we do not do something about it. The reality is, we could all continue to enjoy eating it as high-grade sushi if we all make an effort to curtail our consumpition in order to let stocks recover. But that unfortunately makes too much sense… people would rather consume it now and not worry about the future. They will pay the price by never having it again due to extinction.
Revkin also goes on to talk about what a joke the current quote system for fishing this species is:
The fact is that for years the quota in the West has also been much too high, due to commercial and recreational fishing industry lobbying. And we continue fishing in the spawning area. (Earlier this month I lost a long-running lawsuit against N.O.A.A. to close the Gulf to gear capable of catching bluefins during the spawning season.) It’s all subject to limits but the limits are too high. If they weren’t too high, we would not have the problems. So we have a collapsed western stock and a rapidly declining eastern stock because of greed all around.
U.S. boats have been catching a small fraction of their quota (about 10 to 15 percent of what they’re allowed) in recent years. That percent of the quota will increase as the quota comes down, making things look better. But the quota remains higher than the catch, so the quota is not a limit. It’s like limiting your pasta intake by reducing your limit from 10 pounds of spaghetti per meal to five pounds per meal. Nobody is eating five pounds, so it’s not a limit.