Demography of the bonnethead shark, Sphyrna tiburo (Linnaeus, 1758), in the southeastern Gulf of Mexico

Abstract

The bonnethead shark, Sphyrna tiburo, is one of the most abundant species in catches from the Gulf of Mexico, particularly from Campeche. It is mainly caught with gill nets and it is available throughout the year. A demographic analysis was carried out, incorporating the best available information about its life history, such as age at first maturity, fecundity, longevity, sex ratio (1:1) and age-specific natural mortality. The age and growth data used come from northern individuals of the Gulf of Mexico. The first run was done to obtain the demographic parameters under natural conditions. Other simulations varying age at first capture and incorporating fishing mortality were made to estimate the rate of change of the net reproductive rate (R₀), generation time, intrinsic rate of increase and doubling time. Using an age-structured dynamic model, R₀ was projected until the year 2010. The results of the simulations showed that S. tiburo has a higher reproductive potential than other sharks. This analysis will allow us to establish the management strategies for the fishery.