And it is the sharks' usefulness, naturally, that becomes the death of them. Precisely how many of the animals have died and how many are left is the subject of endless debate. The World Wildlife Fund guesses that somewhere between 40 million and 70 million sharks were killed in 1994. Last spring the National Marine Fisheries Service imposed commercial quotas that reduced the legal catch of large Atlantic coastal sharks by 50 percent, to 1,275 metric tons a year. So while it may be illegal to catch a great white on purpose, if one should foul in your net or hook itself on your line . . .
Sharks are by no means the only pelagic animals under stress.
It's estimated that 13 of the world's 17 major fisheries are overfished or in decline. Most sharks reproduce slowly, some species only every third year. Some don't reach breeding age until they are more than 10 years old. And many species produce small litters when they do breed. Basking sharks, for example, pup only six offspring per litter.