Reproductive Biology of the Scalloped Hammerhead Shark Sphyrna lewini Griffith & Smith (Sphyrnidae) in the Gulf of California

Reproductive biology of scalloped hammerhead shark Sphyrna lewini, was investigated in eight shark fishing camps in the Gulf of California (Mexico) from 1994 to 1996. A total of 1 693 specimens were determined total length (TL), total weight, sex and the gonadal maturity. The total length range was from 41 to 363 cm for females and from 43 to 290 cm for males. The sex proportion of embryos, neonates and juveniles in most of the cases was 1:1; however, this was not the case for adults, where the proportions varied at the sampling sites. Sexual maturity was reached at 170 cm for males and 207 cm TL for females. The gestation period was 11 months and the highest fecundity was 32 embryos. The June births were between 41 and 53 cm TL. The presence of neonates, gravid females, and small juveniles in the east coast of the Gulf of California and in La Paz Bay indicates that these areas are used as a nursery for S. lewini. In addition, the presence of male and female adults during the summer in the central and southeastern Gulf of California suggests that these two places are important as mating areas.