There are currently over 32,000 species of fish described worldwide. A sampled assessment of 1,500 randomly chosen species of marine and freshwater fishes, including elasmobranchs (sharks and rays), was carried out to track the status and trends of this species-rich group, in collaboration with the IUCN SSC Shark Specialist Group , the IUCN SSC/WI Freshwater Fish Specialist Group and the Global Marine Species Assessment .
Fish play a diversity of roles within our aquatic ecosystems, as predators, prey, and in disease control, providing a large biomass contribution to aquatic food webs. As a result, fish are one of the most globally important natural resources to humans. Some of the world’s poorest countries derive 75% of their animal protein from fish; without this the number of starving people would significantly increase.
Based on the Sampled Red List assessment of the world’s fish, 15% of species are estimated to be threatened with extinction. Many commercially exploited fish are classed as threatened, particularly in the marine environment. Overall, freshwater fish appear at a higher risk of extinction compared to marine fish. Threats to the world’s fish are manifold, ranging from overexploitation (a predominant threat in marine environments which are often considered limitless, but also a serious threat to freshwater fish) to modification of waterways, water abstraction, pollution, and invasive species in freshwater habitats.