Critical Thermal Maximum (CTM) of Cultured Black Rockfish, Sebastes schlegeli

Abstract

Critical thermal maximum (CTM) was evaluated for the adult black rockfish Sebastes schlegeli. Adult black rockfish were acclimated at 24°C, and then exposed to temperatures from 24 to 33°C. The oxygen consumption rates (OCR) were measured using an automatic intermittent-flow-respirometer (AIFR) during the exposure period (from 119.3- to 143.5-h). Black rockfish were kept in constant darkness and subjected to gradual temperature increase (1°C 12 h-1). The OCR increased from 94.5 to 214.2 ml O2 kg-1 h-1 as the temperature rose from 24°C up to 29.4 - 30.9°C. The OCR abruptly increased again thereafter, reaching of 245.8 - 412.7 ml O2 kg-1 h-1 at 32°C. This study suggests that the CTM for adult black rockfish is 29.4 - 30.9°C under the condition of the increasing temperature rate at 1°C 12 h-1 following the acclimation at 24°C.