The Bycatch Problem
It’s hard to believe, but the United Nations estimates that about 27 million tons of fish each year—a third the volume of the regular commercial catch—are caught and then tossed back (usually dead) because they are the wrong species, too small, damaged in capture or exceed a particular quota. And some estimates peg the real amount at closer to 40 million tons. In the industry, it’s known as unwanted “bycatch.”
Shrimp and prawn trawlers are the worst culprits; in some fisheries, 15 tons of fish are dumped for every ton of shrimp landed. The U.S. National Marine Fisheries Service reports that 84 percent of the shrimpers’ hauls in the Gulf of Mexico are bycatch. This includes some 35 million juvenile red snapper killed annually, in a commercial and recreational fishery that’s already on the brink of collapse from overfishing.
Longline vessels setting as many as 80 miles of hooks in pursuit of tuna and swordfish are the biggest source of mortality for billfish such as the marlin, a sports species whose sale is outlawed in the U.S. Between 1989 and 1992, American longliners reported about 30,000 billfish taken in the Atlantic, half of which were dead when returned to the water.
Nor does the longliners’ impact stop with fish. A recent study conducted by Charles Wurster of the Marine Sciences Research Center at the State University of New York indicated that bycatch mortality on diving birds caused by tuna longlines may by “even more severe than from driftnets.” (The UN General Assembly has voted unanimously for a moratorium on large-scale driftnets on the high seas—“walls of death” which, in 1990, entangled 42 million non-targeted animals.)
An estimated 100 million longline hooks are set (mostly by the Japanese) in the Southern oceans each year, resulting in the death of about 180,000 albatross and petrels that hit the buoyed lines as they feed into the water. That total cannot account for the offspring that subsequently starve; and it doesn’t do much for the fishermen either, since about half the birds that dive for the bait get away with it.
Marine mammals are equally vulnerable. Despite the UN-imposed global ban on high-seas driftnets, some 600 Italian vessels continue to utilize them in the Mediterranean Sea, where sperm whales wrapped in these netted curtains have washed up dead along beaches. After the Humane Society of the U.S. filed suit, a federal judge last February ordered the State Department to either work out a compromise or impose an embargo against Italy.
Dolphins often swim with schools of tuna and, in the Eastern tropical Pacific, an estimated seven million dolphins have been killed in the U.S. tuna fleet’s encircling purse-seine nets since 1959. A public outcry, spearheaded by the Earth Island Institute, forced precautionary dolphin methods to be implemented in 1990. That same year, major canneries including Bumble Bee, Starkist and Chicken of the Sea refused to sell tuna caught by foreign purse-seiners that kept entrapping dolphins. By last year, the wanton slaughter of dolphins dropped to below 5,000—down from nearly 500,000 annually before measures were taken. Still, Congress is now debating lifting a ban on tuna imports from Mexican ships that persist in setting where dolphins swim, claiming this creates a problem with the North American Free Trade Agreement (NAFTA), which encourages tariff-free trading between the U.S., Canada and Mexico.
U.S. shrimpers are now obliged to install Turtle Excluder Devices (TEDs), which shunt the turtles out a trap-door of their trawls, and will go a long way toward saving the estimated 55,000 adult turtles that were dying in them previously. Other technologies are also being developed by fishermen themselves—including acoustic net alarms to warn dolphins away from swordfish driftnets, and lobster pots with biodegradable vents.
According to the United Nations Food and Agriculture Organization, a 60 percent reduction in bycatch could be achieved quickly by improving the selectivity of fishing gear; developing greater cooperative research between scientists, industry and managers; and the application of new technologies. Unfortunately, the final version of the landmark United Nations high-seas treaty last December weakened a provision that would have forced nations to use selective gear to cut bycatch. The U.S., under pressure from its own fishing industry, succeeded in amending the treaty language to require countries to do so only “to the extent practicable.”