• Cambaroides japonicus;
  • crayfish;
  • distribution;
  • lethal temperature;
  • Pacifastacus leniusculus;
  • tolerance

ABSTRACT: Lethal limits of high temperature were studied to clarify the effects on the survival of the endangered Japanese crayfish species Cambaroides japonicus and the alien species Pacifastacus leniusculus. After the acclimation period for 2 weeks at 16°C, the temperature was raised at a rate of 1°C per week. As a result, the ultimate upper lethal temperatures of C. japonicus and P. leniusculus were 27.0 and 31.1°C, respectively, and the lethal temperature for P. leniusculus was significantly higher than for C. japonicus. The natural distributions of these two species are discussed in terms of the temperature tolerance.