A team of scientists from the Galapagos Whale Shark Project (GWSP), the Galapagos National Park Directorate (DPNG) and the Georgia Aquarium (GA) embarked upon a second annual expedition to Darwin Island on the week of the 9th of September. The expedition goal was to carry out field work for the long term study on the unique grouping of whale sharks sighted passing by seasonally in the waters of the far northern region of the Galapagos Archipelago.

The Galapagos Whale Shark Project cofounded by Dr Alex Hearn and Jonathan R Green a decade ago has been working to better understand the movement ecology and reproductive biology of female adult whale sharks sighted in greater numbers in the Galapagos than anywhere else in the world. Since the beginning of the project the scientists from the GWSP have carried out ground breaking science for the conservation of this endangered species, working in collaboration with multiple organizations and expert scientists from around the world.

This year, the team, reduced to small numbers due to continued impact of the COVID-19 pandemic for travel and global collaborations, was made up of five members from the abovementioned organizations.

During a week of work they carried out various field methods to gather data that will continue to shed light on the remaining mysteries of this species. During this expedition the main activities carried out were photo-ID of four whale sharks, satellite tagging (SPLASH tags) of four sharks, tagging with animal-bourne video cameras (CATS) of one shark and sampling of the microbiome of two of the sharks.

The data from the photo-ID and the satellite tagging provides information of estimates on population size, residency indexes, mortality, and allows for both passive and active tracking of the animals, respectively. The satellite tagging also provides information on the activities Galapagos Whale Shark Project Press Release Image 1. A satellite tag placed on the dorsal fin of an whale shark. ©Sofía M Green performed by the whale sharks underwater, giving insight about their diving behaviour and habitat preference and use in the water column.

Meanwhile, the animal-bourne video cameras allow a visual insight of their movements underwater and any possible interactions with other individuals both inter- and intra-specific in areas not easily observed by the human eye, while also avoiding any change in behaviour that may occur from human presence. The camera’s also have inbuilt accelerometers which allow fine scale resolution data collection of their movements in different planes during various activities such as foraging, navigating, diving, and more.

The microbiome samples serve for innovative research which is looking at the role of bodyassociated microbiomes in determining elasmobranch health and how the unique microbiome might be involved in host immunity, nutrition, disease and waste- processing.

This year the Galapagos Whale Shark Project team reports a low frequency of whale shark sightings which are probably influenced by the fluctuation of sea surface temperatures (SSTs) due to climatic patterns such as the warming of waters with El Niño Southern Oscillation (ENSO) and the cooling counter event of La Niña. Specifically in 2021 NOAA reports a neutral climate state with “near to below average” SST’s with a 70-80% chance of La Niña during the northern hemisphere winter 2021-22.

Jonathan R Green states “The lower SSTs in April and May brought early sightings of whale sharks but in June and July temperatures again rose with a corresponding decrease in numbers and frequency of sightings from reports from the dive Masters, visiting divers, [and our team].” With climate change it is predicted that the Oceanic phenomena’s such as El Niño and la Niña will occur with higher frequencies and thus it is probable that this will affect the regularity with which whale sharks are sighted in their known aggregation locations. The shift in seasonal sightings and possibly also location of sightings make it more complicated to apply proper measures of management for the conservation of this species. The impact of climate change on this species is uncertain and is being considered in current and future studies.

The GWSP would like to thank the Galapagos National Park Directorate (DPNG), the Georgia Aquarium (GA), the Galapagos Science Center (GSC), the Galapagos Conservation Trust (GCT), the World Wildlife Fund (WWF), Save Our Seas Foundation (SOSF) and Galapagos Shark Diving (GSD) for their funding and/or support in this project.

For further information:

galapagoswhalesharkproject@gmail.com

www.galapagoswhaleshark.org