Biology and morphometry of the oceanic whitetip shark, Carcharhinus longimanus (Carcharhinidae), off north-eastern Brazil

The oceanic whitetip shark, Carcharhinus longimanus, represented 29% of the elasmobranch catch in 197 longline sets conducted off Brazil in the equato rial Atlantic (1 degrees N to 9 degrees S, 30 degrees to 40 degrees W) from 1992 to 1997. A total of 258 individuals were caught (121 males and 137 fe males) ranging from 71 cm to 250 cm (total length, TL). No significant diff erence was detected in the length vs eviscerated weight relationship betwee n sexes. Significant differences between sexes were found for twelve morpho metric features. Claspers 2.6-21.0 cm in length were found in males measuri ng 114 to 235 cm. In individuals up to 187 cm, claspers are flexible and sm aller than 10 cm. A substantial increment in size of claspers occurred in 1 90 cm individuals. Testes ranging from 3 to 170 g were recorded in individu als 95 to 235 cm in length and epididymis width varied from 0.4 in to 2.4 c m. In females, nidamental gland width varied between 0.5 to 4.4 cm in 105 t o 250 cm. Ovary weights from 5 to 180 g were recorded. Vitellogenic follicl es were not observed in females smaller than 180 cm, but in larger individu als they vary from 1.0-4.4 cm. Liver weights ranged from 180 g in a 100 cm female to 7,500 g in a 250 pregnant female. First maturity class is 180-190 cm for both sexes. Three pregnant females (203, 213 and 250 cm in length) were caught with embryos of approximately 20 cm (n = 3), 10 cm (n = 4), and fertilised eggs (n = 9), respectively. Males and females were longer and h eavier from July through December. Testis and liver weights in males were a lso significantly higher during this period. The mean weight of ovaries and follicle diameter decrease during this period which can be attributed to o vulation. A new-born shark caught in August with an unhealed umbilical scar suggested that birth takes place at about 70 cm.