Distribution and reproductive biology of the lentil bobtail squid, Rondeletiola minor (Cephalopoda: Sepiolidae) from the Portuguese Atlantic Coast

Abstract

The present study investigated the distribution and general and reproductive biology (size, maturation, fecundity) of the bobtail squid Rondeletiola minor from the Portuguese Atlantic Coast, based on 387 specimens collected between 1997 and 2009, of which 240 were fully analysed. The species was mainly encountered on the southern shelf of the Algarve, in depths of 175–375 m. Females had mantle lengths (ML) of 10.9–21.2 mm and were mature from 13.4 mm, while ML in males ranged from 10.4 to 18.9 mm with the smallest mature specimen being 10.4 mm long. The potential fecundity varied from 5 to 460 (mean 228). Mature ova ranged in numbers from 2 to 115 (mean 26), having a diameter of 1.5–3.0 mm (mean 2.0). Oocytes were present in the ovary at different stages of maturity. We also encountered mature specimens with elevated reproductive indices in all sampled months, which is a sign of a multiple spawning strategy with asynchronous ovulation. A peak in reproductive activity is indicated in autumn. R. minor seems to exhibit a comparatively long spawning season, adapted to a life in variable environmental conditions.