Mass spawning is the most common method of reproduction in fish. It involves all the members of a particular species in a particular area getting together in a single place to release sperm and eggs together. Number of sperm produced by a single male fish is normally billions, to increase the chance of fertilization occuring. Sperm can survive in the environment of the water for a period of time to allow external fertilization. Species that use this method include Tuna, Sardines, Pilchards, Cod, Mackeral, Pollack, Hake, Tailor, Halibut, Eels, Herring and Menhaden.