Reproductive biology of the spotback skate, Atlantoraja castelnaui (Ribeiro, 1907) (Chondrichthyes, Rajidae), in southeastern Brazilian waters

Abstract

Specimens of Atlantoraja castelnaui were obtained from seven commercial fishing vessels overating in southeastern Brazilian waters, from March 2005 to April 2006. A total of 53 males, ranging from 17.9 to 111.0 cm in total length (TL) were examined. Based on analyses ot the clasper gland and clasper length, testes weight, testicular lobes diameter and alar thorns, size at maturity was estimated to be 91.0 cm TL. Fifty-four females were examined ranging from 17.4 to 116.0 cm TL. Accordin2 to observations of uterus width, oviducal gland width, ovarv weight and diameter of the largest vitellogenic follicle, size at maturitv was estimated as 105.0 cm TL. Vitellogenesis would start when follicles attain a diameter of 1.0 cm, and ovulation when attaining 3.0 cm of diameter. The maximum number of vitellogenic follicles of this species was 20. Inspite of the tact that A. castelnaui is an oviparous species, and therefore, with a relativelv high fecundity when compared with other elasmobranchs, its big size makes it an extremely vulnerable species to fishery pressure, being even already considered as an endangered one. Because of that, the knowledge of its reproductive parameters will lead to an adequate management of the stocks.