Diving Deeper into the Underlying White Shark Behaviours at Guadalupe Island, Mexico

Photo credit: © Marc Aquino

Diving Deeper into the Underlying White Shark Behaviors at Guadalupe Island, Mexico

Marc Aquino-Baleytó | Vianey Leos-Barajas | Timo Adam | Mauricio Hoyos-Padilla | Omar Santana-Morales | Felipe Galván-Magaña | Rogelio González-Armas | Christopher G. Lowe | James T. Ketchum | Héctor Villalobos

Ecology and Evolution, 2021; 11:14932–14949

DOI:  https://doi.org/10.1002/ece3.8178

Abstract

1. Fine-scale movement patterns are driven by both biotic (hunting, physiological needs) and abiotic (environmental conditions) factors. The energy balance governs all movement-related strategic decisions.

2. Marine environments can be better understood by considering the vertical component. From 24 acoustic trackings of 10 white sharks in Guadalupe Island, this study linked, for the first time, horizontal and vertical movement data and inferred six different behavioural states along with movement states, through the use of hidden Markov models, which allowed to draw a comprehensive picture of white shark behaviour.

3. Travelling was the most frequent state of behaviour for white sharks, carried out mainly at night and twilight. In contrast, area-restricted searching was the least used, occurring primarily in daylight hours.

4. Time of day, distance to shore, total shark length and, to a lesser extent, tide phase affected behavioural states. Chumming activity reversed, in the short term and in a non-permanent way, the behavioural pattern to a general diel vertical pattern.

Keywords: Telemetry, Behavioural states, Movement strategies, Energy costs, Bayesian inference