Capture fisheries resources are highly diverse. FAO landing statistics refer to about 2 500 species or group of species most of which are finfish. By far the most numerous fish species, and those most important to aquaculture and fisheries, are teleosts, or bony fish, which in the sea extend from small "grazing" species such as anchovy to large active predatory fish such as tuna. A similarly wide range is also found in freshwater, with the most important species from a production point of view belonging to the carp family. These account for over half the total of inland waters fisheries production.
Marine capture fisheries resources are usually considered close to full exploitation worldwide with some 52 percent fully exploited, 24 percent of them over exploited, depleted or recovering from depletion and 21 percent only with some capacity to produce more than they presently do. The overall situation of inland capture fisheries resources is not as well known but is likely to be as serious or worse, considering the much larger environmental impact they are subject to.
Capture fisheries resources are usually exploited and managed on a stock-by-stock basis. Stocks present a wide range of characteristics that affect the fisheries exploiting them: their mono- or multi-species composition, size, value and distribution (e.g. in the high seas). High seas resources such as tuna or marine mammals require international collaboration for their management.
There is no comprehensive global database on fish stocks and monitoring of their state needs significant improvement.