Habitat use and occurrence of the bull shark (Carcharhinus leucas) near the Sabine Pass inlet of Texas and Louisiana

Abstract

The role of nearshore Gulf of Mexico habitats adjacent to Sabine Pass, a tidal inlet forming the southernmost border between Texas and Louisiana, in bull shark (Carcharhinus leucas) life history as well as the impact of selected environmental variables on this species' utilization of said habitats were characterized during late spring through summer, 1992-1999. A total of 730 bull sharks was captured in 91.4 m long entanglement nets of varying depth and mesh sizes deployed adjacent to jetty and/or beachfront sites near Sabine Pass. Total length, weight, and sex of bull sharks and hydrographic data (water temperature, salinity, dissolved oxygen content, and water clarity) were recorded at various frequencies. Bull shark catch-per-unit-effort (CPUE) increased as water temperature, salinity, and water clarity decreased and dissolved oxygen content increased. Average bull shark CPUE across the 8-year period was 1.921 individuals/kilometer-hour. May and July exhibited the highest monthly capture rates, while the highest yearly CPUE occurred in 1992 when sampling effort was lowest. Neonates through subadult life history stages (less than 199 cm TL) made up 100% of the Sabine Pass assemblage. The relationship between weight and total length of the bull sharks was best correlated (r=0.954) by a power model. Overall sex ratio was 1.5 males to 1 female. The Sabine Pass study area functions as a nursery ground for early life stages of bull sharks, and as such, requires proper management to protect neonate and juvenile constituents.