Growth and reproduction of the mud shrimp, Upogebia major (de Haan, 1841) (Thalassinidea: Upogebiidae) on the intertidal mudflat of the Southern Sea, Korea

Abstract

Samples of the mud shrimp Upogebia major were monthly collected from April 2015 to April 2016 on an intertidal mudflat in Southern Sea of Korea. The sex ratio of the U. major significantly equivalent to 1:1 (male = 701, female = 669). The relationship between carapace length (CL) and body weight (BW) was significant (P < 0.001). There was significant difference on the slope of regressions of log CL versus log BW between males and females, indicating sexual dimorphism in growth. The gonadosomatic index (GSI) varied monthly, reaching a maximum in November 2015 and a minimum in February 2016. The highest values of the GSI coincided with the breeding period, and there was a significant difference between the mean GSI of females with non-eyed and those with eyed eggs (P < 0.001), indicating that Upogebia major is a consecutive breeder. There was a significant relationship between CL and the number of eggs (EN) in the egg stages (P < 0.001), but there was no significant difference in the slope and intercept of the regressions of CL versus EN between females carrying non-eyed and eyed egg stages. Based on the dry weights in the egg stages, reproductive output was determined to be 0.257 ± 0.005. The Von Bertalanffy growth function parameters were CL∞ = 40.71 mm, K = 0.78 year−1, C = 0.4, and WP = 0.15 for males, and CL∞ = 40.48 mm, K = 0.62 year−1, C = 0.61, and WP = 0.95 for females. The growth performance index (φ′) was higher in males (3.11) than in females (3.01). The dimorphic difference in growth between sexes was discussed in terms of reproductive cycles and moulting.