A large white shark cruising near the Farallon Islands, west of San Francisco. Courtesy Scot Anderson, NOAA

Juvenile cod caught in a gill net. Cod were once incredibly abundant in the North Atlantic. No longer.
Courtesy NOAA

Capture fisheries (conventional fishing), has quadrupled since 1950. In the past 15 years, aquaculture has surged as well.
Courtesy FAO

POSTED 13 AUG 2001

You protect the sharks, he argues, and you endanger the swimmers. This despite the fact that shark attacks are increasing only slightly year after year.

(Florida took a more logical step on Sept. 6 by banning "swim-with-the-sharks" expeditions -- which used bloody fish to bait sharks so divers could groove on the proximity of razor-sharp chompers.)

Sharks are increasingly attractive to the fishing industry, but they aren't the only fish suffering from a global frenzy to extract protein from salt water. According to United Nations Food and Agriculture Organization, 47 to 50 percent of the world's major marine fisheries are considered fully exploited, and 24 percent to 28 percent are overexploited or recovering from depletion. That leaves only 25 percent to 27 percent capable of greater exploitation.

Heading for the plate
If you like to eat, the argument over overfishing is crucial. Fish now provides one-sixth of overall animal protein, and as global population grows, fish had better sustain that role. If overfishing continues, the FAO predicts that only 74 million tons of fish (wild and from fish farms) will be available for us to eat in 2010. That number could rise to 114 million tons with stringent, effective regulation.

Fishing scientists have long assumed that such a high level of fishing can harm fish stocks, especially when you add millions of tons "by-catch" (unwanted fish) that are killed while catching edible fish.

The general pattern over the past century has been to fish top predators until scarce, and then catch their prey, a process called "fishing down the food chain."

Overfishing can do more than endanger our food supply. Some scientists say it causes widespread changes in ocean ecology -- degradation of reefs, destruction of bottom grasses, eutrophication of estuaries. Although fertilizer, runoff, sedimentation and exotic species are destroying ecosystems, they argue that overfishing came first -- and if it's controlled, ecosystems often recover.

With increased attention to global warming, some scientists say climate plays a major role in the fishing equation.