Spawning dynamics and maturity patterns of the Indian squid, Uroteuthis (Photololigo) duvaucelii (A. d'Orbigny, 1835), along the southeastern coast of India

Uroteuthis (Photololigo) duvaucelii (A. d’Orbigny, 1835), is an economically important squid species along the southeastern coast of India. This study presents a comprehensive analysis of its reproductive biology, based on the specimens collected during an exploratory fishery resources survey in the region. The results provide valuable insights into the reproductive patterns of this important fishery resource. The overall sex ratio was 0.9:1 (Male:Female), indicating a predominance of females over males. The length at 50% maturity (L50) was estimated at 138 mm dorsal mantle length (DML) for Males, and 118 mm for females, showing that females tend to mature earlier. Observation of maturity stages revealed that sexually mature (stage V) males and females were found throughout the year, with a reproductive peak in April, though no spent individuals were observed during the study. The maximum number of total eggs recorded in the ovary was 69,629 with 841 mature ova. Potential fecundity ranged from 544 to 20,865 eggs, with an average of 9,114. Relative fecundity (RF) value ranged from 8 to 115, while potential reproductive investment (PRI) values ranged from 0.01 to 0.196. The maximum egg weight was observed between 1.6 and 1.7 mg. Histological examination of the ovary and oviduct (stages IV and V) confirmed that this species follows an iteroparous spawning strategy, characterised by multiple spawning events throughout the year.