Reproductive biology of Carcharhinus acronotus in the coastal waters of South Carolina
Abstract:The reproductive biology of blacknose sharks Carcharhinus acronotus in the western North Atlantic Ocean was studied by examining specimens collected in the coastal waters of South Carolina. Males begin the maturation process between 875 and 910 mm fork length (L F), as indicated by the presence of functional claspers and siphon sacs. The presence of vitellogenic oocytes and developing oviducal glands and uteri indicated that females begin to mature at c. 870 mm L F. Length at which 50% of the population reached maturity was 896 and 964 mm L F, equivalent to 4·3 and 4·5 years, for males and females, respectively. Gonado‐somatic indices suggested that spermatogenesis and vitellogenesis began after December. Mating took place during the end of May and the beginning of June. Fertilization occurred during late June and early July, suggesting that female blacknose sharks were capable of sperm storage. Based on the timing of fertilization and occurrence of females carrying near‐term pups in late May and early June, the gestation period for blacknose sharks was c. 11 months. Female blacknose sharks reproduced biennially based on the absence of vitellogenic oocytes in near‐term females and there being no indication of vitellogenesis in postpartum females. Male blacknose sharks were capable of reproducing annually as indicated by turgid genital ducts, which were observed in all mature males collected during late May and early June.
Document Type: Regular Paper
Publication date: 2004-06-01