2017 Volume 64 Issue 2 Pages 95-105
The present-day distribution of Carassius auratus was surveyed in 1129 inland water bodies on mainland Kyushu, and the Osumi and Amami-Ryukyu Islands (5 and 31 islands, respectively). The frequency of occurrence of the fish on the Amami-Ryukyu Islands [30 of 516 locations on 10 islands (Amamioshima, Tokunoshima, Iheya, Noho, Izena, Okinawa, Kume, Minamidaito, Miyako and Ishigaki Islands)] was significantly lower than on mainland Kyushu (65 of 241 locations). On the basis of old records and a verbal survey of 266 local residents, it is likely that C. auratus has become extinct on 10 islands (Kikai, Kakeroma, Uke, Okinoerabu, Yoron, Yagaji, Tokashiki, Tarama, Iriomote, and Yonaguni Islands), there being no records of its occurrence at any time on 11 additional small islands. Several specimens with unusual body colors, such as orange and blue (transparent-scale) types, were found, their likelihood of occurrence on Amami-Ryukyu (19 individuals from 7 populations) being significantly greater than on mainland Kyushu (1 individual from 1 population). Local Amami-Ryukyu residents also recalled previous occurrences of silver (ordinary type), orange, blue (possibly transparent-scale type), green (possibly transparent-scale type), white and black individuals. It was concluded that Amami-Ryukyu Islands C. auratus, characterized by various body color patterns, is now endangered. The color variation could be a conservation symbol for C. auratus and the freshwater ecosystem of Amami-Ryukyu Islands, if the native status of the species is verified.
