长江鲢、草鱼原种——人繁群体生长差异与生化遗传变化↑（*）

用完全随机区组设计的方法在三个池塘中进行了源于长江的鲢，草鱼原种与封闭人繁群体子三代１龄鱼种阶段的生长比较试验。结果表明；原种鲢，草鱼的体长绝对增长高出封闭人繁子三代群体１７－２１％，相对增长快１３－１８％；体重绝对增重高出２５－２６％，相对增重快１５－２０％。但这些差异均未达数理统计上差异显著的标准。

GROWTH DIFFERENCES AND BIOCHEMICAL GENETIC CHANGES BETWEEN WILD STOCK AND HATCHERY POPULATIONS OF SILVER CARP AND GRASS CARP FROM YANGTZE RIVER

The growth comparison experiment for wild stock and isolated hatchery population (third generation from wild) from Yangtze River of silver carp and grass carp was conducted with completely random block design during their first year stage. Compared with hatchery population, the wild stock of silver carp and grass carp was 17-21% higher in absolute growth rate of body length, 13-18% higher in instantaneous growth rate of body length; 25-26% higher in absolute growth rate of body weight, 15-20% in instantaneous growth rate of body weight. However, these differences were not significant (P>0 05). Allelic frequency variation on 18-19 loci of 10 enzymes and protein from the wild stock, F1 of wild stock in hatchery and isolated hatchery population of silver carp and grass carp were analyzed with isoenzyme electrophoresis. It was found that there were no significant difference in mean proportion of polymorphic loci (P), but there were significant difference in the average heterozygosity per locus (H) among 3 tested groups of silver carp and grass carp respectively at a rank of wild stock> isolated hatchery population>F1 of wild. Cluster analysis showed that the genetic distance between isolated hatchery population and wild stock was higher. In addition, a specific EST-5 band was found in the wild stock of silver carp and grass carp. This study indicats that isolated hatchery population is worse than the wild population in growth, and have a slight biochemical genetic differences with wild population.