Growth and reproduction of the Japanese mantis shrimp, Oratosquilla oratoria (De Haan 1844) in the coastal area of the Tongyeong, Korea

Abstract

Growth and reproduction of the Japanese mantis shrimp, Oratosquilla oratoria (De Haan 1844), were investigated based on samples from July 2014 to August 2015 in the Tongyeong, Korea. A total of 2,621 samples was collected (1,380 females and 1,241 males) during the study period. The number of female was observed more frequently than that of male ( P<0.001). The mean body length (BL) was 128.54±0.38 mm in females and 126.87±0.42 mm in males, respectively. The mean body weight (BW) was 31.23±0.28 g in females and 31.06±0.32 g in males, respectively. The females were larger than males in BL (P<0.01). There was a significant difference in the length-frequency distributions between females and males (P<0.05). A linear regression analysis using natural log transformed data of females was lnBW=2.8498(±0.0235)lnBL-10.4339 and lnBW=2.8727(±0.0272)lnBL-10.5153 of males, respectively. We found no significant difference in the slopes of the regression between ln BL and ln BW for the both sexes (P>0.05), but a significant difference in the intercepts of the regression for the both sexes (P<0.01). The Von Bertalanffy growth function parameters were BL∞ = 184.5 mm, K = 0.72 year−1, C = 0.36, and WP = 0.45 for females and BL∞ = 183.75 mm, K = 0.82 year−1, C = 0.38, and WP = 0.22 for males. The growth performance indices (φ') were 4.39 for females and 4.44 for males. The gonadosomatic index (GSI) varied monthly. GSI reached a maximum in May and a minimum in November. The highest values of the GSI coincided with the spawning period of O. oratoria. Larger individuals of O. oratoria have earlier spawning season than smaller ones. The size at sexual maturity (〖BL〗_50) of females was estimated as 96.5 mm.