Movement patterns and residency of bull sharks, Carcharhinus leucas, in a marine protected area of the Gulf of California

Photo credit: © Miguel Grau

Movement patterns and residency of bull sharks, Carcharhinus leucas, in a marine protected area of the Gulf of California

Frida Lara-Lizardi | E. Mauricio Hoyos-Padilla | A. Peter Klimley | Miguel Grau | James T. Ketchum

Environmental Biology of Fishes (2022)

DOI: https://doi.org/10.1007/s10641-022-01223-x

Abstract

In the southwestern Gulf of California one of the most successful marine protected areas (MPA) worldwide is found: Cabo Pulmo National Park (CPNP). Due to the level of protection and availability of prey, a large population of bull sharks (Carcharhinus leucas) exists in this MPA. Historical records about the abundance and distribution of these sharks in the park are scarce. Here we describe the movement patterns of 32 bull sharks within CPNP using a passive acoustic telemetry array (N = 13) located along the park to examine how the residency of the species change spatially and temporally. Environmental variables were taken in situ (HOBOs) and complemented with satellite information (MODIS aqua). The mean residence index (RI) was 0.365 (SD ± 0.2143). Sharks were resident from December to May, whereas they were absent from August to October. Most bull sharks preferred water temperatures below 28 ºC and depths as shallow as 14 m as well as deeper waters ranging from 70 to 160 m. They thus occupy a wide range of habitats with diverse prey, from shallow to mesophotic reefs. Differences in the residency of males and females occur in response to temperature during the different seasons, resulting in sexual segregation. Our results suggest that females segregate from males probably for reproductive reasons (pupping in another area) or to feed on more energy-rich prey resulting in increased growth rates. This study provides information germane to the protection and management of bull sharks in CPNP.

Keywords: Acoustic telemetry, Temporal patterns, Residency index, Sexual segregation, Shark conservation.