The status of shark species is reviewed based on the available data. A review of the history of shark fisheries demonstrates that intensive shark fisheries are not sustainable. Numerous problems are encountered in assessing shark populations: a general lack of biological and fishery data, lack of suitable models, and lack of validated age estimates. Sharks have an unusual combination of biological characteristics: slow growth and delayed maturation, long reproductive cycles, low fecundity and long life spans. These characteristics make them vulnerable to overfishing. A preliminary evaluation of the status of shark species is made on the basis of historical data, the reproductive potential of each species, and the level of exploitation of the species. In this document, exploited shark species are classified numerically according to their vulnerability. The majority of these species are listed as Category 1, indicating that there are not sufficient data to assess the species. Available data indicate that sharks are very vulnerable and are threatened by overexploitation in many parts of the world.