Reproduction and population dynamics of Penaeus chinensis (Decapoda: Penaeidae) on the western coast of Korea, Yellow Sea

Abstract This paper describes reproduction, population structure, growth, and size at sexual maturity of a penaeid shrimp ( Penaeus chinensis ) in the western coastal areas of Korea, Yellow Sea. The reproductive season was April–June, with peaks in June. Insemination took place from October to July, and larvae form during April–June. Recruitment to the fished population takes place in August, and is compatible with a 1 year life cycle and a single breeding season. Size at 50% sexual maturity (CL 50 ), determined from both mature females and inseminated females, was 39.19 mm CL and 38.71 mm CL, respectively. Fecundity was related to body size, ranging from 315,620 ova in the smallest female to 642,140 ova in the largest. Diameter of ova ranged from 250 to 370 μm. Size distribution of the population was similar in the 2 years of the study. Specimens were not found within the studied area during winter (January–March), indicating that the shrimp had moved outside the range of the fishery, probably to deeper water. Growth was estimated by the modified von Bertalanffy growth function incorporating seasonal variation in growth. In both years females ( K=0.96 yr −1 and L ∞ =58.6 mm CL ) grew faster, reaching a larger size at age than males ( K=0.45 yr −1 , L ∞ =54.9 mm CL ). This is indicated by differences in growth performance indices ( ϕ ′) between females (1.75) and males (1.39).