Developmental changes in low-salinity tolerance in larvae and juveniles of longtooth grouper, Epinephelus bruneus

Abstract

Survival and growth rates of some marine fishes such as red-spotted grouper, E. akaara and false kelpfish, Sebastiscus marmoratus during early larval to juvenile stages have improved drastically by rearing fish in low-salinity water. Cultured longtooth grouper, Epinephelus bruneus, suffer from high mortality rates during larval stages and the growth rate of juveniles is poor. Low-salinity tolerance data are needed for E. bruneus larvae and juveniles as a first step to apply low-salinity water rearing to mass seed production. This study revealed changes in low-salinity tolerance in E. bruneus larvae and juveniles associated with development using a logistic regression model included in a generalized linear model (GLM). The median lethal salinity doses (LD₅₀) of 24 h rearing based on the predicted death probability curves for GLM at the mid-larval (19-20 dph), late-larval (48-49 dph), early juvenile (68-69 dph), and late juvenile stages (335 dph) were 10.5, 14.2, 4.4, and 2.7 psu, respectively. Grouper larvae are probably less tolerant to low salinity than other coastal fish species such as olive flounder, Paralichthys olivaceus and sea bream, Pagrus major.