In 2001 Dení Ramírez Macías, has established and maintained a research project on whale sharks in the Gulf of California and surrounding areas: La Paz Bay, Conception Bay, Los Cabos and Revillagigedo Archipelago. We also work together local community groups from Bahía de Los Angeles (Pejesapo group) and Nayarit (Chacon group) and with the University of Nayarit, to share data in order to increase the knowledge of the migratory species in the Gulf of California. We are proud to have 1135 photo-ID sharks in our database.
The goal is to determine whale shark population size!
In Mexico we currently have several lines of research involving students. For the study we use different tools:
Photo-identification technique. Apparently every whale shark looks similar, but this isn’t true. Each shark has a unique pattern of lines and spots, it’s like their fingerprints! As scientists we take picture from the left side of the shark, just behind the gills, which we call photo-identification. With this technique we can estimate their abundance, fidelity and movements by comparing the photos from different localities
In La Paz bay we have 549 identified sharks, and we name them! Here they have a lot of fidelity which means they spend a lot of month feeding and they returned year after year around 60% of the sharks in each season are knowing sharks.
Satellite tagging to know the movements of whale sharks once they leave the areas of aggregation. We placed satellite tag on juvenile and adult whale sharks present in the Gulf of California, in order to asses if differences in their migratory patterns exist. Juvenile and adult whale sharks displayed clear differences in their movement patterns. Juveniles remained in the tagged site and moved north into the Gulf of California based on tracks and photo-identification data. Juveniles showed a high degree of site fidelity to the Gulf of California, in contrast with adults, which left the tagged site immediately. The five adult whale sharks tracked from the Gulf of California, which included four adult females that were visually assessed to be pregnant, all moved a significant distance following tagging and spent the majority of their time in the open ocean. The females moved south and then to the north, offshore of the peninsula of Baja California, whereas the only male tracked moved straight to the south. We also recorded diving behavior: the adult male spent more time diving than the females and juveniles. Two whale sharks dove 1286 m. our next step is to tag in the Archipelago of Revillagigedo.
The regular presence of female sharks, almost exclusively pregnant, in deep waters in the southern part of the Gulf of California suggests that their presence is related to breeding. A very small, free-swimming whale shark pup was sighted at Espíritu Santo Island on 4 July 2015 to support this theory.
Analysis of injuries on sharks, which we evaluate each season for the managements of the species.
Behavior: The assessment of behavioral changes when whale sharks are in the presence of people and tourism. This study includes the use of drones and cameras on whale shark’s dorsal fins to monitor the sharks.
Contaminants: Analysis of the effects of contaminants such a pesticides and leather microplastics on the whale shark.
Ultrasound: we are using a underwater ultrasound machine to prove the pregnancy on the whale sharks and giant manta rays, can you imagine to see a whale shark´s embryo or manta?….watch our manta video…
Economic valuation of species and tourist satisfaction in the service of tourism with the species.
Carrying capacity study. The maximum number of people that may visit the whale sharks in La Paz Bay at the same time, without causing negative effect on the whale sharks and maintaining a the quality of visitors’ satisfaction.