The biological consequences of taking fish out of the ocean before they spawn are severe depletion of the population and possible commercial extinction. Smaller Nets Legal Gillnets are vertical walls of netting designed to entangle fish by their gills. While driftnets longer than 2.5 kilometers are illegal, smaller nets are regularly used to catch swordfish, shark and tunas. Gillnets entangle anything larger than the net's mesh size, resulting in tremendous amounts of bycatch. Longlines are single-stranded lines many miles long, with up to 3,000 baited hooks.
Drift longlines targeting tunas and swordfish catch every creature that bites one of the hooks.
Marine experts say that because of their unique characteristics, tunas, sharks, swordfish and marlins fish often sought by the recreational anglers are particularily hard hit. The North Atlantic population of swordfish is in a free fall, having declined 42 percent. An estimated 40,000 juvenile swordfish were discarded dead by the U.S. commerical fleet in 1996. Bycatch is the No. 1 killer of sharks worldwide. U.S. longliners in the Atlantic and Gulf of Mexico killed and discarded an estimated 40,000 blue sharks in 1995.