Distribution and Abundance of the Ryukyuan Subspecies of the Ayu Plecoglossus altivelis ryukyuensis: Results of a Survey Made in 1986

Abstract

The distribution and abundance of an endangered subspecies of the ayu Plecoglossus altivelis ryukyuensis was determined on the three major islands, Amami-oshima, Tokunoshima, and Okinawa Islands, in 1986. The fish was observed only in five streams in the southern part of Amami-oshima Island. Among these five streams, the majority of fish were found in the Yakugachi River. While the number of fish in this particular stream was approximately 3.5 xlO4, in all other streams the densities were much lower, and we therefore conclude that this subspecies is threatened and some attempts should be made for conservation of this fish. © 1992, The Japanese Society of Fisheries Science. All rights reserved.