1. Sharks have an unusual combination of biological characteristics: slow growth, delayed maturation, long reproductive cycles, low fecundity and long life spans. Sharks produce small numbers of live young that hatch or are born fully developed, and are relatively large at birth. Many commercially important species of sharks have nursery areas in shallow coastal waters. All these factors make sharks extremely vulnerable to overfishing. The new fisheries and markets that have appeared in the last two decades have greatly increased the fishing pressure on sharks throughout the world.
2. Species specific data on shark fisheries is scarce and difficult to obtain. Consequently, our report is modest and far from being complete. However, we have shown that nearly all the species for which we have catches or landings data for more than ten years are in severe declines.
The documented declines are probably indicative of what is happening to many species in undocumented fisheries. For example, the thresher shark population has declined severely off the western coast of the United States. Because the thresher is also being fished in the Atlantic by several nations, it is likely that Atlantic populations have suffered similar but undocumented declines. Our evaluations can only confirm Holden's (1968) observation that most elasmobranch fisheries collapse following initial exploitation.
3. Concerns about overfishing and the collapse of shark stocks have engendered worldwide attempts to manage and conserve sharks. If these attempts at management and conservation of sharks are to be successful, we must do the following:
a) We need to better understand the shark fisheries and their effects. Efforts must be made to collect species specific data on the shark fisheries. These efforts must be directed to the lowest data collection levels by fishery workers. It will take a concerted effort by interested agencies and countries to improve the training of fishery workers in shark identification before meaningful statistics from shark fisheries can be expected. In the authors' experience, this can be done by training programmes and the use of simple, inexpensive regional guides to the species found in local fisheries.This may require international agreements among concerned nations and reductions in catches and bycatch. Given the current, worldwide interest in the short-term exploitation of sharks for fins and meat, attempts at the protection of shark stocks are likely to be difficult. Unless efforts are undertaken promptly to reduce present catch rates and bycatch, the future of the shark resources is very bleak.b) A conservation ethic for sharks must be developed. Educational programmes that explain the role of sharks in the ocean, the value of sharks as a resource, and their vulnerability to overfishing, may be one of the cheapest and most effective methods to promote the rational and sustainable use of natural resources. The attitude that sharks are man's "competitors that reduce the abundance of certain valuable resources" (Taniuchi 1990), is still common. Educational programmes must be directed at the public as well as to fishery managers. Fishery managers must be made aware that sharks do not support intensive fisheries, so that they can prevent the unregulated development and irrational overexploitation of shark fisheries.
c) Shark fisheries need to be managed to ensure their long-term conservation and sustainable use (see FAO Code of Conduct for Responsible Fisheries, paragraph 7.1). Levels of fishing effort should be commensurate with the low reproductive capacity of these species (CoC 7.1.8). Appropriate measures should be taken to minimise shark discards (CoC 7.6.9). Timely, complete and reliable statistics on catch and fishing effort should be maintained and disseminated (CoC 7.4.4).
