Distribution and reproductive biology of the little cuttlefish Sepiola atlantica (Cephalopoda: Sepiolidae) around Anglesey, North Wales

Abstract

Sepiola atlantica were captured in seine nets at twelve locations around the coast of Anglesey, UK. Animals were most abundant on the very sheltered shore of Y Foryd Bay and the wave-exposed shore of Traeth Penrhos, and these two locations were further sampled seasonally to examine the seasonal occurrence, population structure and reproductive biology of S. atlantica. Sepiola atlantica (5-28 mm dorsal mantle length (DML)) migrated inshore seasonally and Wrst appeared in July where they attained peak abundances between July and August at seawater temperatures of 17°C. Numbers declined between September and October as temperatures fell below 15-16°C, and in late October, they migrated oVshore. Male S. atlantica was signiWcantly smaller and matured at a smaller DML than females. The number of spermatangia on the bursa copulatrix of female S. atlantica varied seasonally attaining maximum numbers in October with a mean of 22 spermatangia on the bursa copulatrix of Y Foryd Bay females. At Y Foryd Bay and Traeth Penrhos, the number of spermatophores in male and potential fecundity in female S. atlantica ranged between 1 and 147 and 25 and 141, respectively. The spermatophoric complex and gonadosomatic index showed a high degree of variability in individuals of similar wet body weight with the female gonad constituting a far greater percentage of the total wet body weight than the male gonad. It is concluded that S. atlantica of all sizes and maturity stages congregate in the shallow waters around Anglesey between July and October when environmental conditions are favourable for enhanced growth and maturation and where the high numbers of animals enhance opportunities for mating.

Untitled

“…Implantation area of spermatangia is an enlarged area of distal oviduct (Rodrigues et al, 2012). According to Jones and Richardson (2011) species Sepiola atlantica contains 22 sprematangia in its bursa copulatrix, and by Rodrigues et al (2011) it was reported that implanted sprematangia in the bursa copulatrix could survive up to 104 days.…”

“…Spermatangia are implanted in bursa copulatrix, which is located in the genital opening of females, or into the wrinkled area (Jones and Richardson, 2011), which is called seminal receptacle. Implantation area of spermatangia is an enlarged area of distal oviduct (Rodrigues et al, 2012).…”