Age determination by skeletochronology of the Japanese giant salamander Andrias japonicus (Amphibia, Urodela)

Yamasaki Hiromi

Taguchi Yuki

Minami Shinji

Kuwabara Kazushi

Shimizu Norio

広島大学総合博物館研究報告

Bulletin of the Hiroshima University Museum

[PISSN] 1884-4243

[EISSN] 1884-3999

[NCID] AA12459864

In the past several years, a number of studies have been carried out on the behavioral and reproductive ecology of the Japanese giant salamander Andrias japonicus, but the age and longevity of A. japonicus has not yet been studied. In this study, we attempted to establish an age determination method using specimens (age: 1 to 11 years old) from Hiroshima City Asa Zoological Park that lived and died in captivity. The cross sections of phalangeal bones were nearly circular in shape, and hematoxylinophilic lines that were interpreted as lines of arrested growth (LAGs) were observed in the periosteal tissue; this suggests that this technique can be used to estimate the age of A. japonicus. The number of LAGs was one less than the number of winters that each individual experienced. We could observe LAGs in both frozen and 10% formalin specimens. LAGs could be confirmed even for specimens that had been fixed in formalin for up to 30 years. By using this method, it was suggested that the lifespan of this species could be determined from specimens existing in museums, zoos, and aquariums worldwide. It also showed potential for providing important conservation information, such as generation time and age structure of populations in the field.

giant salamander

Andrias japonicus

age determination

skeletochronology

amphibians

natural monument

Zoology [ 480 ]

eng

広島大学総合博物館

Copyright (c) 2017 広島大学総合博物館 Hiroshima University Museum

[ISSN] 1884-4243

[NCID] AA12459864