The flesh of many fish are primarily valued as a source of food and there are many edible species of fish. Today, fisheries are estimated to provide 16% of the world population's protein, and that figure is considerably elevated in some developing nations and in regions that depend heavily on the sea. Other marine life taken as food includes shellfish, crustaceans, sea cucumber, and jellyfish. Roe are also harvested.
Fish and other marine life have uses apart from food. Pearls and mother-of-pearl are valued for their lustre. Traditional methods of pearl hunting are now virtually extinct. Sharkskin and rayskin which are covered with, in effect, tiny teeth (dermal denticles) were used for sandpaper. These skins are also used to make leather. Sharkskin leather is used in the manufacture of the hilt of traditional Japanese swords. Sea horse, star fish, sea urchin and sea cucumber are used in traditional Chinese medicine. Tyrian purple is a pigment made from marine snails Murex brandaris and Murex trunculus.
Sepia is a pigment made from the inky secretions of cuttlefish. Fish glue is made by boiling the skin, bones and swim bladders of fish. Fish glue has been valued for its use in products from illuminated manuscripts to the Mongolian war bow. Isinglass is a substance obtained from the swim bladders of fish (especially sturgeon), it is used for the clarification of wine and beer. Fish emulsion is a fertilizer emulsion that is produced from the fluid remains of fish processed for fish oil and fish meal.
Fish may also be collected live for research observation or for the aquarium trade.