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

Abstract

The critical thermal maximum (CTM) of black rockfish, Sebastes schlegeli, was evaluated. Black rockfish were acclimated at <TEX>$24^{\circ}C$</TEX>, and then exposed to temperatures from 24 to <TEX>$33^{\circ}C$</TEX>. Black rockfish were kept in constant darkness and subjected to a gradual temperature increase <TEX>$(1 ^{\circ}C\;12^{-1})$</TEX>. The oxygen consumption rate (OCR) was measured using an automatic intermittent­flow-respirometer (AIFR) during the exposure period (from 119.3 to 143.5 h). The OCR increased from 94.5 to 214.2mL <TEX>$O_2 kg^{-1}\;ww\;h^{-1}$</TEX> as the temperature rose from 24 to <TEX>$29.4-30.9^{\circ}C$</TEX>. Subsequently, the OCR increased abruptly, reaching 245.8-412.7mL <TEX>$O_2 kg^{-1}\;ww\;h^{-1}$</TEX> at <TEX>$32^{\circ}C$</TEX>. This study suggests that the CTM for black rockfish is <TEX>$29.4-30.9^{\circ}C$</TEX> when temperature is increased at <TEX>$1^{\circ}C\;12h^{-1}$</TEX> following acclimation at <TEX>$24^{\circ}C$</TEX>.