Reproductive cycle and maturity stages of Johnius carutta Bloch, 1793 off Visakhapatnam, south-east coast of India

摘要

A total of 3,406 gonad samples of Johnius carutta caught off Visakhapatnam (during 2008-'09), were analysed to study the reproductive cycle and maturity stages. Seven maturity stages were observed in the gonads. Spawning season was assessed based on gonado-somatic index and monthly occurrence of matured females based on the general appearance of gonads, its relative length to the abdominal cavity and developmental stages of ova. Monthly distribution of ripe (stage VI) and spent (stage VII) females were considered for ascertaining the probable spawning season. The restricted brief spawning period lasts for three months from February to April and the species spawn only once in a year. The peak breeding activity was observed in the month of February (26.64%) followed by March (18.62%) and April (15.38%) in which high gonado-somatic index (GSI) values (February 3.50%; March 3.46%; April 2.74%) were recorded. Spent females were observed from June to December with peak in the month of August (13.78%) andOctober (10.80). The size at first maturity was estimated at 17.5 cm in females. The fecundity varied from 35,650 to 1, 96,496 in individuals of 140 to 217 mm and its mean fecundity rcorded was 81,290 ± 5014 (n=38).