PARÁMETROS REPRODUCTIVOS DE LOS TIBURONES PILOTO (Carcharhinus falciformis), MARTILLO (Sphyrna lewini) Y AZUL (Prionace glauca) EN EL PACÍFICO MEXICANO

Abstract

ABSTRACT The blue shark Prionace glauca, silky shark Carcharhinus falciformis and scalloped hammerhead shark Sphyrna lewini are the shark species most caught commercially in the Mexican Pacific. They are considered as priority species for the fishery management; however biological characteristics are unknown and these characteristics are necessary to elaborate adequately these management plans. In this context, the aim of this study is estimate the reproductive parameters of these shark species and recognize possible mating zones and nursery areas in the Mexican Pacific. The biological information used, comes from studies done in Centro Interdisciplinario de Ciencias Marinas (CICIMAR) for Baja California Sur and the Gulf of Tehuantepec, and bibliographic information from the Mexican pacific. The reproductive parameters estimated were: maturity size (L50), where C. falciformis did not present differences between sexes, but there were differences between geographical areas (Baja California Sur, Colima and Gulf of Tehuantepec). Females of S. lewini showed variations between areas (Gulf of California, Michoacán and Oaxaca). P. glauca showed differences in both sexes for Baja California, Baja California Sur and Colima. Also was analyzed the sex ratio in embryos; this parameter was closed to 1F:1M in the different localities for the three species. There are not relationship between the litter size and maternal size, except for S. lewini in the coast of Michoacán. Blue sharks use the western coast of Baja California Sur as mating area and as secondary nursery area considering their high abundance of juveniles. Silky sharks use the western coast of Baja California Sur as mating area, however the Mexican central Pacific were observed pregnant females and neonates, they use the Gulf of Tehuantepec as nursery area, however, the reproductive season could not be defined. The, Scalloped hammerhead utilize three localities as nursery area in the Mexican Pacific: Gulf of California, coast of Michoacán and Gulf of Tehuantepec. There is a propose than the adjacent areas to the shark nursery areas would be considered as potential mating areas.