Short-term rearing of red sea bream in deep seawater and its effects on rigor mortis

Deep seawater (DSW) under the euphotic layer is cool and constant in temper ature, rich in inorganic nutrients but contains less organic matter and mic roorganisms than surface seawater (SSW). We reared red sea bream Pagrus maj or in DSW, SSW and SSW chilled to the same temperature as DSW (CSSW) for 87 days. Red sea bream successfully acclimated to DSW but the temperature of DSW seemed too low for growth of red sea bream. To know the effects of DSW acclimation on muscle properties, we compared post-mortem changes of rigor mortis and degradation of ATP-related compounds during storage at 0 degrees C and 10 degrees C, and IMPase activity 30 and 87 days after the start of rearing. Acclimation to DSW for 30 days caused the delay of rigor mortis, e specially in fish stored at 10 degrees C. The delay of the rigor mortis was supposed to be caused by the low temperature of DSW. The relationship betw een the progress of rigor mortis and the degradation of ATP was, however, n ot clear. Differences in rigor mortis among experimental groups became uncl ear after rearing for 87 days, with the decrease of the difference of water temperature between SSW and DSW.