Do cartilaginous fishes need protection? We think so, but in southern Africa most people might think otherwise. There seem to be plenty of sharks, rays, and chimaeras about, and to many people these `inedibles' are trash fish, `man-eaters' and objects of hatred, that could stand for culling or even extermination. However, cartilaginous fishes, because of their essentially mammalian life-history style, are endangered by ever-increasing human exploitation. The threefold increase in fisheries for cartilaginous fishes since World War II highlights the biological, environmental and management difficulties with these fishes that need careful consideration to insure their long-range survival. Cartilaginous fishes are typically slow-growing, long-lived, mature late in life, and have a low reproductive rate. In addition the females of most species grow to a larger size than males. These life-history characteristics make cartilaginous fishes easy to overexploit, and make sustained fisheries for them nearly impossible with the nonselective practices of most fisheries operations. Numerous case histories for such fisheries indicate that initial exploitation usually results in rapid declines in catch rates and in some instances a complete collapse of the fishery.
http://www.biodiversityexplorer.org/chondrichthyes/conservation.htm
http://www.biodiversityexplorer.org/chondrichthyes/conservation.htm