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Spotted Eagle Ray Population Study in Cozumel, Mexico

We are seeking to fund this project as a partnership between VeterHands and conservation scientists who are actively engaged in existing studies of Spotted Eagle Rays. It is also a vital step in attaining a Course Director rating for our Lead Instructor, Liang Chen. Liang will coordinate and supervise the activities of local volunteers and assigned interns as well as collect and assemble data to support these studies being conducted by marine biologists.

The Spotted Eagle Ray (Aetobatus Narinari) is a common and spectacular sight on coral reefs throughout the Caribbean region. However, very little is known about the biology and ecology of this species, and unfortunately, populations have been declining. Researchers at the Center for Marine Resource Studies have been studying the ecology of eagle rays for a number of years, and we are proposing an extension of the project to Cozumel. The global population of spotted eagle rays is listed as “near threatened” by the International Union for the Conservation of Nature (IUCN). Eagle rays are most threatened from overfishing in areas of the world like Cozumel, where inshore and artisanal fishing is a way of life. The waters of Cozumel are one of very few places in the world where divers are able to frequently spot large schools, making them a valuable attraction to the tourism industry – an important player in the national economy.

Since Eagle Rays are both predator and prey, the population numbers are vulnerable to dramatic shifts in either direction when their environment is changed. This makes researching them as an indicator species essential to conservationists and economists alike. It is important to attempt to understand their foraging behavior, population dynamics, and life histories when they and their prey are such valuable tourist attractions and commodities, respectively. Eagle rays, however, are capable of traveling large distances at high speeds, making them difficult to keep track of: Consequently, very little has been known about their behavior. The proposed study sites in Cozumel are interesting and unique, because they include protected marine park areas where fishing and depredation by humans is illegal, open waters where fishing activities are legal and newly found areas which do not exist within the marine park, but still have been under extremely low fishing pressure due to their remote locations. These combined areas will allow us to study the populations and the potential impact of associated human activities.

The main goals are to identify local and/or migratory individuals within the population at Cozumel, then describe movement and migratory patterns of the rays, determining critical habitat areas and their use with regards to breeding and hunting. We would like to determine if these areas are used year-round, and if individual rays display preferences for particular areas or exhibit territorial behavior. This data then can be applied to management plans aimed to increase and stabilize populations.

With the help of software, researchers have been able to identify individual eagle rays based on the pattern of white spots on their body through mapping and comparing the spots and markings on individuals to those that have been added to the database. This method is particularly adventitious because unlike methods that require capturing or tagging individuals, all that is needed is a clear photograph that shows these unique “fingerprint” patterns. When combined with the geolocation and time the photo was taken, it then becomes a very effective tool for estimating Eagle Ray movement patterns.