Longevity in captivity of an endangered Japanese frog of Hiroshima prefecture, Rana porosa brevipoda

Abstract

An endangered Japanese frog R. porosa brevipoda, a subspecies endemic to Japan was the most threatened frog in Hiroshima pref. Captive breeding for the conservation of R. p. brevipoda was first attempted in Japan in 1993. In 1993, one remnant, the Kisacho-population, located in an isolated basin of Hiroshima pref., was faced with extinction due to the reconstruction of paddy fields to increase rice productivity. Therefore, about 150 froglets were collected from the Kisacho-population to establish a captive stock in October 1993 and maintained by a volunteer group, who were scattered in Kanto District (Okochi et al., 1997). We succeeded in breeding the species by employing a more natural approach (Numazawa et al., 1995). We bred the frog outdoors and without the use of hormone injections in consecutive years, from 1995 to 2000 and the frogs survived until 2001 (Numazawa, 2003). After capture, the frogs survived in an artificial environment from 2431 to 2842 days. The specimens were caught as froglets for captive breeding on October 4 1993. The Kisacho-population has been reported to breed from the beginning of May to late June, before the paddy fields are drained for agricultural purposes (Utsunomiya et al., 1996a). Therefore, it can be estimated that the frog's longevity is approximately 7-8 years in captivity.