1.1 Historical background
In November 1994, the Convention on International Trade in Endangered Species (CITES) passed a resolution requesting that the Food and Agriculture Organization of the United Nations (FAO) and other international organizations to establish programmes to collect and assemble the necessary biological and trade data on sharks. This CITES resolution reflects the concern that shark stocks are being depleted rapidly and an attempt must be made to understand and quantify the effects of the world trade on shark populations. The purpose of this work is to indicate the species of sharks that may be threatened by overexploitation or trade, in response to the CITES request. This work lists all species of sharks that are reported in both commercial and recreational fisheries throughout the world, and assigns a status category to each, based on historical fishery trends, on reproductive potential of the species, and on the impact of fisheries upon the species. The authors believe that a species approach is the only meaningful and practical approach to shark conservation and management. Generic compilations of elasmobranch or "shark" landings, although interesting, convey little understanding of what is happening to species in a fishery, and are of little practical use in management and conservation attempts.
In the early 1980s, political and economic changes throughout the world affected fishing markets and operations. In particular in China, shark fins were no longer considered as a luxury product and it led to a significant growth of domestic consumption thanks also to the reduction of tariff rates on imported shark fins (Cook 1990, Rose 1996). In other areas, declining catches and rising prices of traditional food fishes made under-utilized sharks an inexpensive source of protein. These two factors engendered numerous and diverse shark fisheries throughout the world. By the late 1980s, shark fisheries everywhere were growing at a rapid pace fuelled by the demand and the high shark fin prices. By the mid 1990s, the ex-vessel price for dry shark fins had reached US $60 per kilogram, providing sufficient incentive to harvest sharks, even when the meat was not marketable. Currently, shark fisheries encompass the entire world and catch most large species of coastal and oceanic sharks.
While shark fisheries were growing in the early 1980s, the pelagic swordfish and tuna longline fisheries were also growing dramatically. These fisheries normally catch a large proportion of sharks as bycatch. In the early years of those fisheries, sharks were usually released or discarded. By the late 1980s, the high price of the fins caused previously released or discarded sharks to be retained as bycatch, and to be brought on board to be finned. Today, shark bycatch is probably a significant portion of the total shark mortality.
The history of the shark fisheries indicates that intensive fisheries are not sustainable, and that initial exploitation is followed by, at best, a rapid decline in catch rates or, at worst, by a complete collapse of the fishery (Holden 1974). Examples of shark fisheries that collapsed are the California soupfin shark fishery (Ripley 1946), the New England porbeagle fishery (Casey et al. 1978), the Australian school shark fishery (Olsen 1954), the English basking shark fishery (Parker and Stott 1965), and the California thresher shark fishery (Cailliet et al. 1991). Once a shark fishery has collapsed, it takes many decades for the stocks to recover, if they recover at all.
In the past, most shark fisheries were small artisanal fisheries that caught whatever species of sharks were locally or seasonally abundant, or intensive regional fisheries that targeted individual species for specific products: liver oil in the cases of the soupfin and basking sharks, and meat in the cases of the porbeagle and school sharks. Fishery administrators and the public generally had little interest in shark fisheries, because they were usually small. The rapid growth in the size and value of the shark fisheries throughout the world, along with increasing shark bycatch and recreational fishing, and the known vulnerability of sharks to overfishing, have engendered worldwide concerns and attempts to manage and conserve sharks. In addition to the economic concerns for a valuable resource, public attitude towards sharks in some countries has changed dramatically. The conservation ethic and concern for wildlife have been extended to encompass sharks, and, in many parts of the world, the public has developed an acute interest in conserving sharks.
Attempts to manage or conserve sharks have been few, and usually engendered by economic concerns about declining fisheries. Australia has had a shark fishery since the turn of the century, and it imposed more restrictions on licenses and fishing methods in 1988 (Stevens 1993). The sand tiger shark, Carcharias taurus, received protected status in the Australian state of New South Wales in 1984 (Pollard 1996). In New Zealand, shark management started in 1986 over concerns of declining catch per unit effort (CPUE). In South Africa, the great white shark has been protected since 1991 (Compagno 1991). In the United States, concerns about a rapidly growing fishery and overfishing led to a fishery management plan for the Atlantic coast in 1993 (NMFS 1993). Protected status has been given in April 1997 to five species in the United States on the Atlantic coast: the great white shark; the whale shark; the basking shark; the sand tiger shark; and the bigeye sand tiger shark. Shark fisheries along the western coast of the United States for shortfin mako and thresher sharks have been regulated by state agencies for many years. In 1989, the states of California, Oregon and Washington enacted an inter-jurisdictional fishery-monitoring plan for thresher sharks (Hanan et al. 1993).