Artisanal shark fisheries have been an important source of food and employment in Mexico for many years. In the Gulf of Mexico, this multispecific fishery is based on the seasonal abundance of several shark and teleost species. To obtain fishery and biological information needed to manage the fishery and conserve shark stocks, intensive monitoring of artisanal shark landings was undertaken from November 1993 to December 1994. The State of Campeche had the highest landings and effort. October 1994 had the highest monthly catch per unit effort for all species and areas combined (27.2 sharks per trip). Rhizoprionodon terraenovae (46%), Sphyrna tiburo (15%), and Carcharhinus limbatus (11%) accounted for most of the landings numerically, and the highest catch per unit effort for C. limbatus occurred late in the year as a result of increased landings attributable to an annual southward migration from USA to Mexican waters. The high proportion of neonate and juvenile sharks in gill-net catches from shallow coastal waters suggests that the main shark nursery areas are under heavy fishing pressure. In light of the heavy exploitation of shark resources, the Mexican National Fisheries Institute recommends a number of precautionary actions to avoid the collapse of this fishery. Resumen. Las pesquerías artesanales de tiburones han sido una importante fuente de alimento y empleo en México durante muchos años. En el Golfo de México, esta pesquería multiespecífica está basada en la abundancia estacional de diversas especies de tiburones y peces. Para obtener la información biológico-pesquera necesaria para manejar la pesquería y conservar los stocks de tiburones, se realizó un monitoreo de las capturas artesanales de tiburón entre noviembre de 1993 y diciembre de 1994. Campeche presentó las mayores capturas y esfuerzo. En octubre de 1994 se registraron las mayores CPUE para todas las especies y áreas combinadas (27.2 tiburones por viaje). Rhizoprionodon terraenovae (46%), Sphyrna tiburo (15%) y Carcharhinus limbatus (11%) constituyeron la mayoría de las capturas numéricamente y las mayores CPUE para C. limbatus se produjeron hacia finales de año a consecuencia del aumento de las capturas atribuible a una migración anual norte-sur desde los E.U. hacia aguas mexicanas. La alta proporción de neonatos y juveniles capturados en redes agalleras en aguas costeras someras sugiere que las principales áreas de crianza están sometidas a una alta presión de pesca. En vista de los niveles de explotación el INP recomienda diversas medidas precautorias para evitar el colapso de la pesquería.

The Pacific sharpnose shark, (Rhizoprionodon longurio, Jordan and Gilbert, 1882), migrates along the Pacific coast of Mexico. It is captured with gillnets and bottom long lines commonly used in the artisanal fishery of Mazatlan. From a sample of 3 464 individuals, R. longurio was observed to be a viviparous shark of small size, which is born at an average length of 31 cm total length (TL), after a gestation period of 10 to 11 months. The number of embryos showed no statistical relationship to the TL. The average number of embryos per female was 7.4 (σ = 2.01, n = 146) and sex ratio was 1:1. Observations on the growth of the claspers indicated that male maturity begins at 93 cm TL. The two smallest gravid females measured were 83 and 87 cm TL. The rest of the gravid females were at least 92 cm TL. Between 90 and 95 cm TL, the females exhibited an increase in the width of the oviducal gland and its size ranged from 5 to 12 mm. The statistical relationship between weight and length is presented in which females reach a larger size than males. The diet of R. longurio was composed principally of crustaceans and demersal teleost fishes.

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