engleski

Reproductive biology of spiny dogfish, Squalus acanthias, in the northern Adriatic Sea

We studied the reproductive traits of economically important small demersal shark, spiny dogfish (Squalus acanthias), in the Adriatic Sea. We sampled 224 specimens (132 females and 92 males) collected on commercial bottom trawls from 2005 to 2007. The morphometry of gonads, gonadosomatic index and histological examination of gonads were utilised to analyse maturation and gonadal development of the species. The length at 50% maturity was attained at 50.4 cm for males and 72.5 cm for females. Ovarian fecundity ranged from 4 to 18 follicles (mean ± SD: 10.8 ± 4.5) and uterine fecundity ranged from 6 to 18 embryos (mean ± SD: 10.1 ± 3.9), with no significant relation to total body length. The gonadosomatic index and the high proportion of mature spermatocysts in the testes suggests that a majority of mating activity occurs during summer and winter, while the seasonal distribution of the largest ova and full term embryos indicate that ovulation and parturition are limited on spring and summer season. In comparison with other studied areas in the Atlantic and Pacific Ocean, spiny dogfish in the northern Adriatic attained sexual maturity at smaller sizes and obtained higher fecundity values than fish from other regions.

sexual maturity; spermatogenesis; oogenesis; chondrichthyes

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