STUDIES ON THE ARITIFICIAL INDUCEMENT OF REPRODUCTION IN COMMON EEL

Studies on the artificial inducement of reproduction in common eel (Anguilla japon-ica) have been carried out since 1973. The parents were collected from Tai Hu. They were induced by injection with pituitary gland of carp and HCG. The results of induce-ment show that the females can be induced to mature by means of injecting with smalldosage of the gonadotrophie hormones at an interval between 15--20 days each time and5--6 times in total. All the females were matured in 7--8 times, and the method seemsto be of good effect. The spawning of common eel usually takes place in the early morning between 4:00and 6:20 A. M. at water temperature between 18.5--24.5C. The spawning place isjust under the surface of the sea water. Soon after spawning the females begin to takefood and gradualty restore to health. The remnant of ovary absorbs rapidly. Thesephenomena lead us to consider whether the gonad can redevelop and mature again. The 3--days old larvae demonstrated that the digestive organs are incompletelydeveloped, and the yolk sac is nearly absorbed. The intestine is filled with foods andwithin it there is a violent ciliary movement. This may be a kind of special method ofnutrition in transition. The larvae lived 19 days (434 hours).