HISTOLOGICAL OBSERVATIONS ON THE MATURITY OF FEMALE GONAD OF THE SMALL CROAKER,PSEUDOSCIAENA POLY ACTIS BLEEKER

The present paper deals with observations on the cycle of histological changes inovaries of the small yellow croaker, Pseudosciaena polyactis Bleeker. Samples werecollected monthly from Bo Hai and in the northern part of Huang Hai, in May, 1963to June 1964. 1) Maturity. Based upon the macro-and microscopic characteristics the matura-tion of the ovaries can be divided into six stages: Stage Ⅰ-Juveniles; Stage Ⅱ-includingimmature ovaries, and those recovered spent ovaries; Stage Ⅲ-ripening ovaries; StageⅣ-nearly ripe ovaries; Stage Ⅴ-ripe ovaries near spawning or spawning, Stage Ⅵ-spent ovaries and Stage Ⅵ-Ⅳ', Stage Ⅴ'-recovered ovaries. 2) Annual cycle of the ovaries. The ovaries enter into Stage Ⅵ-Ⅱ' in July-Aug.; Stage Ⅱ' in Sept.-Oct.; Stage Ⅲ in Nov.-Jan. (mostly in Dec.-Jan.) this is theoverwinter period; Stage Ⅳ in Mar.-May (often in April); Stage Ⅴ from mid-May tomid-June (mostly in May) this is the spawning period. After the fish releases onebatch of ova the ovary is in Stage Ⅵ-Ⅳ' (or Ⅳ') and later on developes to Stage Ⅴ'.Stage Ⅵ occurs in June. 3) Reproductive cycle Sections of ovaries of each successive age group (2⁺-15⁺)collected during the spawning season showed empty follicles. This indicates that thereproductive cycle of the small yellow croaker is of the plural cyclic type, the adultfish spawning every year. 4) Type of spawning. The ripe eggs of this fish are released at least two batchesin a breeding season. It is evident that sections of ovaries sampled from fishes beforeand after spawning all show oocytes of various sizes.