コウライエビ

Maturation of the ovary of the Korai prawn, Penaeus chinensis (Osbeck) was studied with 52 specimens sampled from catches of survey trawling at two stations in an offshore fishing ground of the Yellow Sea in March, 1981. External shape and internal structure of the ovary were examined. Numerous young oocytes of increasing diameter, produced at the germinal epitherium of the formative region and budded off into the lumen of invagination, were observed from the lumen to the inner part of the egg pouch. The largest oocytes were found along the membrane of egg pouch. Height of the follicle layer changed with development of oocyte. Difference of maturity among different portions of an ovary was not recognized. Maturing ovaries were classified into 4 types (a, b, c and d) based on the egg diameter compositions. These types were characterized by the modal value of egg diamiters, the histological maturation stage of developing eggs, and mean of gonadosomatic index as follow: (a) no mode, pre-yolk stage, 3.67; (b) 110~140㎛, pre-yolk stage, 3.91; (c) 150~190㎛, primary yolk globule stage, 5.25; and (d) 200㎛ and over, secondary yolk globule stage, 11.01. Developing eggs formed an isolated batch from young eggs during the ovarian maturation, and this pattern of oocyte development is considered to belong to the group synchronous type. Relationship between number of developing eggs (E) and carapace length (L in mm ) was expressed in the following equation, for the eggs in the primary and the secondary yolk globule stages.E=0.0770L^(4.0391)(r=0.94)