東北太平洋沿岸におけるヨーロッパヒラガキ（軟体動物門： 二枚貝綱：イタボガキ科）の移入と定着状況について

抄録

The European flat oyster, Ostrea edulis Linnaeus, 1758, a species of edible bivalve native to Europe, was introduced to Japan from the Netherlands in 1952. Seeds collected from specimens were transferred to several areas in Northeastern Japan for aquaculture trials. However, in the 2000s, these trials to introduce O. edulis into Japan were discontinued. Strains of the O. edulis species were preserved in several Japanese laboratories, but since the laboratories were washed away by the 2011 Tohoku Earthquake and Tsunami, the species was considered to be extinct in Japan. However, this study confirmed the survival of the species in several locations in Iwate Prefecture, notably Yamada Bay. This is the first recorded case in Japan of a non-native oyster species, originally introduced through aquaculture, naturalizing in Japan's marine environment. Ostrea edulis has been found in several sites beyond those where it had been introduced previously. This suggests that O. edulis may be expanding into other areas in Japan. Multifaceted discussions on the handling, commercial use, and epidemiological testing of the species will be necessary in the future.