Abundance, distribution and side fidelity of gray whale "Eschrichtius robustus" in Magdalena-Almejas lagoon complex (Baja California Sur, Mexico) during 2019

Abstract

Eastern Gray Whale is known for its population recuperation success and it is one of the most studied whale species because of its near-shore habitat.The abundance, distribution and side fidelity of eastern gray whales on their calving and nursinggrounds in Magdalena-Almejas Bay coastal lagoon system were evaluated withboat surveys countsand photo-identificationin 2019.A total of 845 whales (single and female-calf pairs) were observed during boat transects as well asfourspecies of other cetaceans.The highest number of single whales was registered on 25thof Februarywith 234individualsin Almejas Bayand the highest number of mother-calf pairs was registered on 27thof February with 7 pairs in Santo Domingo Channel. Atotal of 242sightings were madewith a group size range from oneto eightduring photo-identification effort. A total of 319whales were classified in 2019 Catalog using photographic identification. Approximately 10% of the whales which arrived this year has already visited same breeding grounds in previous years.Furthermore, 32% of the photo-identificated animals presented nutritional stress condition. Decrease in population stockand body mass could be a consequence of the presence ofEl Niño event and global warming. Whale-watching activities and scientific research influence was also evaluated. More detailed research and comparations with previous year’s dataset should be required for more precise results