INFLUENCE OF SALINITY AND FOOD-DEPRIVATION ON GROWTH AND RNA-DNA RATIO IN RED DRUM SCIAENOPS-OCELLATUS (PISCES, SCIAENIDAE)

Juvenile Red drum Sciaenops ocellatus held in 30 ppt natural seawater or fresh water were starved or fed ad libitum for six weeks, and sampl ed each week for growth and for determination of RNA, DNA, and protein contents of while and red muscles and liver. Specific growth rate and condition factor were used to compare changes in nucleic acid and pro tein concentrations in fish tissues. Salinity had little effect on gro wth, while starvation caused a significant reduction in all growth par ameters and in the RNA-DNA ratio after three weeks. The RNA-DNA ratios of red and white muscles of the fed fish were greater than those of t he starved fish and also were related to specific growth rate and fish condition factor. Nucleic acid concentrations in liver were highly va riable. Since white muscle predominates and is more easily sampled in red drum than red muscle, and because it has less variable RNA-DNA rat ios than liver, it is the tissue recommended for nucleic acid analysis of physiological condition and growth.