The influence of stocking density on the growth performance of juvenile Russian sturgeon(Acipenser gueldenstaedti)in flowing water cultivation

Nowadays,some countries in Europe,Asia,and North America have developed the techniques for sturgeon artificial breeding according to the conservation acts.Russian sturgeon(Acipenser gueldenstaedti)is one of the rare and valuable fish species,which has become one of the popular sturgeon culture species in China.It has been demonstrated that people tend to get more benefit by increasing stocking density,which may suppress fish growth due to the decreasing of food consumption efficiency and the alteration in metabolic rate induced by crowding stress associated with stocking densities.This study was undertaken to investigate the influence of different stocking density on the growth performance of juvenile Russian sturgeon.Three triplicate groups of juvenilesinitial body weight:(29.7±1.32)gwere reared in nine square concrete ponds(4.4 m×4.4 m×0.45 m)at three stocking densities2.5(SD1),3.6(SD2),4.7 kg/m³(SD3)for 90 days.The results showed that:the weight gain(GBW),length gain(GBL),specific growth rate(SGR)and food conversion ratio(FCR)of the fish at low density(SD1)were(362.01±15.87,55.88±4.77,1.79±0.03,114.95±4.52),respectively,which were significantly higher than those in high density(SD3)(272.30±2.74,46.34±6.22,1.53±0.02,94.49±1.96)(P<0.05).The mortality and greater variation in size and growth of the juvenile fishes in SD3 were significantly higher than those in SD1(P<0.05); Meantime,the protein and fat content decreased while the moisture and ash content increased along with the density increasing,but there is no significant difference(P>0.05).These results suggested that high density has a significant negative impact on the growth preformance of juvenile Russian sturgeon,and the growth suppression caused by high stocking density might be associated with the crowding stress and reductions in both food consumption and food conversion efficiency.