The departure of sperm whales ( Physeter macrocephalus ) in response to the declining jumbo squid ( Dosidicus gigas ) population in the central portion of the Gulf of California

As sperm whales are important predators that control energy flux in the oceans, changes in their population can be used as a sentinel to measure of ecosystem health. The present study conducted a sperm whale survey of the eastern Midriff Islands Region in the Gulf of California over the course of ni...

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Bibliographic Details
Published in:PeerJ (San Francisco, CA) CA), 2024-10, Vol.12, p.e18117, Article e18117
Main Authors: Pérez-Puig, Héctor, Arias Del Razo, Alejandro, Ahuatzin Gallardo, Daniela, Bolaños, Jaime
Format: Article
Language:English
Subjects:
Animals
California
Cetacea
Cetacean
Decapodiformes - physiology
Ecosystem
ENSO
Marine mammal
Mexico
Population Density
Population Dynamics
Population ecology
Predator-Prey Interaction
Sperm Whale - physiology
Water, Underground
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Summary:As sperm whales are important predators that control energy flux in the oceans, changes in their population can be used as a sentinel to measure of ecosystem health. The present study conducted a sperm whale survey of the eastern Midriff Islands Region in the Gulf of California over the course of nine years, recording sightings and collecting photographs of the fluke of sperm whale individuals. A photo-identification catalog was compiled, while individual recapture data were used to estimate the population size in the central portion of the Gulf of California, using a Jolly-Seber POPAN open population model. The results obtained show a yearly population of between 20 and 167 sperm whales, with a super population of 354 sperm whales observed between 2009 and 2015. However, from 2016 to 2018, no sightings of the species were recorded, which coincides with the decline observed in landings of their main prey, the jumbo squid, in the region. General additive model conducted on sperm whale sightings per unit of effort vs jumbo squid landings obtained an adjusted R of 0.644 and a deviance explained of 60.3%, indicating a good non-linear relationship between sightings of this odontocete and its prey availability. This evidence suggests that sperm whales departed the region between 2016 and 2018, due to a documented fishery collapse alongside changes of their main prey into its small phenotype, possibly as the result of increase warming conditions in surface and subsurface waters in the Gulf of California in the last three decades.
ISSN:2167-8359
2167-8359
DOI:10.7717/peerj.18117