STRUCTURE OF OTOLITHS DAILY GROWTH RING OF EMBRYO CHUM SALMON AND ENVIRONMENTAL MASS MARKING

This study marked the eyed egg otoliths of chum salmon from Heilongjiang river and Suifenhe river, by regulating the environment temperature periodically and sustainedly. This experiment consisted of 4 groups: 1 for control, 2 and 3 for regulatling temperature groups and 4 for the group exposed to the open air for a stretch of time. 10000 chum salmon eyed eggs were used in the experiment. The otoliths of chum salmon formed as primordium at the beginning of eyed egg stage and the initial daily growth ring, made up of dark and bright calcium zone, which began to surround the core 5 days later and the daily increment width was (2.6±0.15) μm. Under the proper environmental condition, 30 daily growth rings would be formed during the embryo period, and we corroborated the daily growth ring in sagitta and lapillus. Otoliths marking experiment was conducted when the daily growth ring was stable. With the environmental water temperature changed periodically, the embryo otolith formed the marking area. The picture of daily growth ring, with the darker and brighter stripe and the different daily increment, which was marked by artificial regulating temperature, was different from the natural daily increment, and the rate of marking reached 100%. This experiment obtained precision marking pictures, established fishes otoliths marking and distinquishing technology, which was suited to artificial propagation marking in reproduction and stocking assess for salmons such as chum salmon et al. As the safe, effective, and cheap marking technology, fish otoliths marking method would be used in fish artificial reproduction and stocking widely.