Revillagigedo Archipelago
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March - April 2016

Pristine Seas Expeditions - Revillagigedo Archipelago

In March 2016, partnering with Mares Mexicanos, the Pristine Seas team conducted an expedition to explore the waters around the small reserve—including never before surveyed seamounts. The team traveled to Socorro, San Benedicto, and Roca Partida to evaluate their fish biomass and improve understanding of how the entire ecosystem of the archipelago works. To fully explore the area, they descended to the depths in the DeepSee submersible, deployed remote drop and stereo pelagic cameras, made scuba diving transects, and operated drone cameras. Using high-tech tools and conducting 140 scuba dives allowed the team to get a comprehensive look at the marine environment. While conducting their scientific surveys, they sampled shark populations, swam with San Benedicto’s famed giant manta rays, and observed unique sea fan gardens at a depth of over 80 meters.

Overall, our team of scientists found an interesting mix of tropical and temperate species. They observed a high diversity of sharks, consisting of at least eight species, and a high fish biomass with several endemic species. The abundance of mantas was exceptional. Large predatory pelagic species were also abundant, with sharks and tuna observed regularly. Five species of shark from two families were observed; the most common was the silky shark, occurring at 92% of all locations. Yellowfin tuna were abundant in the waters sampled, appearing in 28% of drops, sometimes in large schools. Olive grouper (Epinephelus cifuentes), and sharks and chimaeras were common. Of these cartilaginous fishes, the purple Chimaera (Hydrolagus purpurescens) was the most abundant and occurred on 40% of the surveys. Tiger shark, Galeocerdo cuvier, was observed at 1,229 m. Prickly shark (Echinorhinus cookie) and Combtooth dogfish (Centroscyllium nigrim) at 1,807 m and 1,134 m, respectively. The team documented new records of elasmobranch species in the Archipelago. With the Dropcams, they found the sleeper shark (Somniosus microcephalus), prickly Echinorhinus cookei and longnose skate (Raja spp). These are the topline principal findings, as the comprehensive scientific results of the expedition are still being determined.

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