摘要：
The growth and development of teleost were more or less directly affected by the environmental factors. Salinity is one of the important ecological factors. The influence of salinity on the survival and growth of marine fish has been demon-strated in many studies. However, distinct results were displayed due to the different abilities of tolerance to salinity among fish species. The milkfish (Chanos chanos), which has a nice marine habitat and an efficient osmoregulation, is widely dis-tributed throughout tropical and subtropical Indo-Pacific. This species occurs naturally and is commercially cultured in fresh, brackish, and oceanic waters as well as in hypersaline lagoons. In the present study, the influences of salinity stress on the survival and growth of milkfish juveniles were assessed and the effects of morphometric attributes on body weight were also evaluated. Juveniles of milkfish [mean weight and total length: (0.215±0.083) g; (2.850±0.356) cm, respectively] were reared at salinities of 0 (fresh water), 10, 20, 27 (sea water) and 35 without acclimation, in triplicate, for 30 d cultivation. The survival rate was recorded and the body weight and morphometric attributes of each individual were measured. Results showed, the lowest survival rate was founded at salinity 0 group (73.33%) when compared with other groups (>90%). The juvenile stage is a special stage during the life history of fish, the juvenile developed not as well as the adults, and cannot adapt to the short-term drastic changes of external osmolality, which may be one of the reasons of the high mortality rate at salinity 0 group. On the other hand, however, the highest rates of weight gain rate (573.94±231.58)% and specific-growth rate (6.23±1.16)% were obtained at salinity 0 group (P0.05). The higher weight gain rate and specific-growth rate were also found in the intermediary groups with salin-ity 20 and 27. It has been suggested that the marine fish often has a better growth rate in water with lower salinity for the rea-son of fish spending less energy on osmoregulation in such conditions. Although it has not been reported that milkfish require a fresh water environment for any part of its life cycle, it did showed well growth performance at fresh water in many studies. Furthermore, recent studies indicated that the true proportion of energetic cost of osmoregulation remains under debate as thought before. The total length (x1), body length (x2), tail length (x3), trunk length (x4), head length (x5), postorbital length of head (x6), eye diameter (x7), snout length (x8), caudal peduncle height (x9), and body height (x10) were measured by QCapture Pro 6.0 software after the cultivation. The correlation analysis, path analysis and determination coefficients were calculated by SPSS 13.0 software. Significant differences (P0.05)。相关分析表明,幼鱼的各形态性状与其体重之间呈极显著的相关关系(P<0.01)。通径分析表明,遮目鱼幼鱼的体长、全长和体高对体重的影响最大,且在不同盐度胁迫下对幼鱼体重的决定作用不同,其他性状对体重的影响较小。建立了盐度胁迫下形态性状对体重影响的最优回归方程。
