AFFECTS OF SALINITY ON GROWTH,MUSCLE COMPOSITION,AND PROTEASE ACTIVITY OF PORTUNUS TRITUBERCULATUS

The affect of salinity on growth,muscle composition,and protease activity of Portunus trituberculatus was studied.The crabs with body weight of(14.45 1.36) g were raised at five salinity levels(11,17,23,29,and 35) for 30 days,after which the growth,composition of water,crude protein and fat in muscles,and protease activity in hepatopancreas and stomach were measured.Results showed that the growth rate,protease activity of hepatopancreas,and stomach all increased prominently with the rise of salinity at the range of 11~29(P0.05),and those targets declined significantly when the salinity reached 35(P0.05).The water content of muscle was not affected distinctly by salinity(P0.05),but the value which below salinity 17 were higher than those up salinity 23.The crude protein and fat of muscle were affected notably(P0.05),the crude protein at salinity 29 was distinct higher than those below salinity 17(P0.05),and the crude fat of muscle increased prominently with the rise of salinity at the range of experiment(P0.05).