Dynamics of growth and spawning in the Indian squid Uroteuthis duvaucelii (Cephalopoda: Loliginidae) from the tropical Arabian Sea

Abstract

The dynamics of age, growth, maturation and spawning of the Indian squid Uroteuthis duvaucelii, were determined by statolith analysis in the tropical southeastern Arabian Sea. In the samples, the smallest male (30 mm Dorsal Mantle Length) was 63 days old and the largest (350 mm DML) 170 days old. The smallest female (32 mm DML) was 62 days old and the largest female (207 mm DML) was 146 days old. The maximum life span was estimated at 6 months. Recruitment to the trawl fishery occurred approximately after two months of age. The average daily growth rates were estimated as 1.22 mm DML/day for females and 1.48 mm DML/day for males. The age at first maturity was estimated as 98 days for males and 106 days for females. Hatch dates were distributed throughout the whole year with two peaks indicating the presence of two cohorts with varying growth dynamics. The best-fitting growth models were the Gompertz growth model for females and the Linear model for the male populations based on the Akaike Information Criterion (AIC). This study suggests that fast growth and a short life span associated with a rapid population turnover may facilitate continuous recruitment to the fishery. From a conservation and management perspective, a closed fishing season during the peak spawning and hatching period (October–November) or in the subsequent recruitment period may prove beneficial to U. duvaucelii population in the Arabian Sea. This study further improves the overall understanding of the life-cycle of multiple spawning tropical squids.