The ayu or sweetfish, Plecoglossus altivelis. The name 'sweetfish' is due to the sweetness of its flesh. In reference to its typical one-year life span. They are also very territorial animals. The adults ascend from coastal waters into the lower reaches of rivers to spawn in the spring. The larvae descend to the sea immediately on hatching and winter there before returning to fresh water again in the spring. Most but not all individuals die after their first spawning. Ayu is an edible fish.It is consequently highly prized as a food fish. The main methods for obtaining ayu are by means of fly fishing, by using a trap, and by fishing with a decoy which is known as ayu-no-tomozuri in Japan. The decoy is a living ayu placed on a hook, which swims when immersed into water. It provokes the territorial behavior of other ayu, which assault the 'intruder' and get caught. Japanese anglers also catch it using a traditional method, cormorant fishing(ukai). On the Nagara River where Japanese Cormorants (Phalacrocorax capillatus) are used by the fishermen, the fishing season draws visitors from all over the world. The Japanese Cormorants, known in Japanese as umi-u (sea-cormorant), are domesticated birds trained for this purpose. The birds catch the ayu, store it in their crop, and deliver it to the fishermen. Also,Ayu is the state fish of owner's country.