Feeding and reproduction of the blue shark, Prionace glauca (Linnaeus, 1758), off Southeastern and Southern Brazil

Abstract

Sampling of individuals of  Prionace glauca was carried out using a surface long-line in four research cruises  of the R.V. Soloncy Moura, of the IBAMA/CEPSUL Institute, in December, 2002, and March, April and July, 2003. A  total of 61 individuals were captured (31 females and 30 males) in 20 hauls of the fishing gear. Gut contents from only 11  individuals could be analyzed, whereby the feeding diet was seen to be based on small Teleostei and Cephalopods, mainly  the fishes  Aluterus sp.,  Balistes sp. and  Diodon sp., and the squids  Illex argentinus and  Chiroteuthis veranyi . The  estimate of uterine fecundity of  P. glauca , which presents a viviparous development, was 34.2 embryos/eggs per female.  There was found to occur a synchronism in the embryonic development to the effect that in December and April (summer  and autumn), when embryos reach were 3 to 12 cm TL long, and females were beginning their pregnancy; and in July,  when embryos were 24 cm TL long, and the females would be in about their fourth month of pregnancy. This synchronism  may vary due to the occurrence of females with eggs implanted on the womb from December till next year’s July. The  results obtained in this work suggest that  P. glauca use the studied area for pregnancy and birth.