Revillagigedo Archipelago
Discovering a shark nursery.
Status of shark populations at the Revillagigedo Archipelago are unknown, although evidence indicates heavy exploitation by fisheries. In March 2019, Ocean Blue Tree provided a vessel and funding for a 3-week expedition to Revillagigedo National Park, Mexico.
The expedition spent 4 days in Clarion a remote island rarely visited by dive operators or scientists. This was a unique opportunity for the scientists who installed 3 receivers and acoustically tagged 9 juvenile Galapagos sharks, suggesting this is a newly discovered nursery ground.
During the expedition the team documented and reported an illegal sports fishing vessel.
Does scuba diving impact oceanic manta ray health?
In the Revillagigedo Archipelago, the high density of recreational diving boats from November to June presents additional threats to oceanic manta rays. Dive operators use fixed lines to provide easy descents to dive sites, and manta rays occasionally become entangled in these lines, as well as lines connected to divers’ surface marker buoys, which cause serious injuries.
During an expedition with Ocean Blue Tree and Pelagios Kakunjá, Dr. Mauricio Hoyos successfully collected 14 biopsies from oceanic mantas. The biopsies will be analysed for reproductive and stress hormones. The analysis of the hormones will allow scientists to identify the patterns of sexual maturation, mating, gestation and postpartum. The scientific team will return during the low season to collect biopsies to compare stress levels when there is low dive intensity.
Increased understanding will allow marine park managers to adjust diving restrictions during peak manta reproductive months to reduce stress on these majestic animals.
Photo: Edwar Herreno
Photo: Edwar Herreno
Photo: Edwar Herreno
Photo: Luis Javier Sandoval