Fishing is a recreational, sporting and hunting activity that involves attempting to catch fish or other aquatic animals. Fishing can be done using a variety of implements such as nets, spears, traps, explosives or by using lines and hooks (with or without a fishing rod). Fishing may also be done purely by hand or by animals using their mouth or claws to catch the fish. Fishing has been practiced by many cultures around the world for thousands of years to provide food, with modern commercial fishing techniques involving large ships and nets some areas have become overfished resulting in the depletion of certain types of fish, therefore many countries have restrictions on fishing to ensure sustainability of the fish stocks. Recreational fishing that involves a rod, line and hook is known as angling, in many cases the angler will return the fish to the water after catching it particularly if the fish is below a certain size and hence young, this is to allow the young fish time to develop and spawn thereby maintaining the population of fish in that area.