Ocean News

Brazilian Manta Mystery

21st August 2009

Seasonal reports of giant manta rays from the small island of Laje de Santos off Brazil have led to an annual migration of scuba divers to the area to view these amazing creatures. There are no regular sightings of this species from anywhere else along the long Brazilian coastline, which leads to some intriguing questions: where do the mantas come from, and where they go when they leave this small marine protected area?

To shed some light on this mystery, FPMM joined forces with the Laje Viva Institute in a collaborative study on the migratory patterns of the giant mantas in southern Brazil. This project is the second phase of the Save Our Seas-funded worldwide satellite tagging study on the species.

In July, after a short flight to the city of São Paulo, our field team consisting of Dr. Andrea Marshall and Richard van Huyssteen, joined up with local marine biologist Osmar Luiz Jr. and Laje Viva Institue founders, Ana Paula Balboni and Guilherme Kodja and travelled down to the coastal town of Santos. From our base in Santos we were able to make daily visits to Laje de Santos.

Having studied the mantas in this area for several years, the representatives from the Laje Viva Institute were able to tell us that the giant mantas frequent these waters in the winter months and stay for only a short time before moving on. They are not known to clean or feed in the immediate area and the reasons behind their brief visits have not yet been established.

Unfortunately, during the three weeks that wewere there, no giant mantas showed up to the island despite concerted efforts by our team and the help of dozens of local divers.

The folks at Laje Viva Institute were stunned by the lack of manta sightings this winter, with only a single individual spotted early in the season in May. This is the first year since they began their observations that the giant mantas have not made an appearance at the island. They did note that weather patterns in the region were unusual for this time of the year and that altered conditions may have caused a change in the mantas? natural behaviour or their standard migratory routes.

The trip was far from a total loss, however. Interest generated by our visit prompted me to give several talks in the local area during our

visit and we were kindly hosted by the aquarium in Santos as well as other venues in São Paulo. FPMM left two satellite tags with the Laje Viva Institute in case the giant mantas do turn up later in the season, and we will be back next year to try again with the Laje Viva Institute and will put on even more tags in a jointly-funded project by the Save Our Seas Foundation and Petrobras.

Despite a somewhat disappointing outcome with regards to our first attempt at satellite tagging giant mantas in South America, I was overwhelmed by the support and interest in the region and thank everyone for their kindness and hospitality. I can?t wait to return next year!