Giant manta ray migratory route

Location: Roca Partida, Revillagigedo Islands (Socorro Island), Baja California, Mexico.

Comments: Captain Dave reports that our guests had two very good days of diving at Roca Partida. It’s hard not to have a good day at Roca Partida!! While the first day was somewhat “surge-y,” with a northwest swell on top of 5 – 7ft seas, the swell disappeared and the seas dropped to 4 – 5ft for their second day of diving.

Highlights included a huge bait ball of skipjacks being hunted by silky sharks and 100-pound yellowfin tuna, a group of five hammerhead sharks that approached within 40 feet of the divers and a blue water drift dive looking for pelagics. All the usual Roca Partida critters were present, including over 30 white tip reef sharks, silky and Galapagos sharks and some curious wahoo. Unfortunately, the giant manta rays didn’t live up to their normal billing with only two animals sighted on the first day and four mantas on the second day and very little interaction with the divers.

Note from Captain Mike – we now believe that the giant mantas likely travel a 1200 kilometre route that includes San Benedicto Island, Socorro Island and Roca Partida as well as the west side and southern coastlines of Baja California at speeds of up to 9 kilometres per hour. Because of the migratory nature of this route, one can never be sure where the best manta sightings will be in the Revillagigedo Islands. While San Benedicto Island has been the “hot-spot” for the last number of years, Dr Bob Rubin (a leading expert on giant manta rays), tells me that he used to see the most mantas around Socorro Island. I find it really interesting that we have had no luck in finding mantas at Clarion Island, the fourth of the Revillagigedo Islands and speculate that Clarion is “off the beaten track” of this migratory route. I also find it really interesting and sad that it has been very rare to observe any giant manta rays in the Sea of Cortez over the last three seasons. I have a theory about this as well and wonder if the mantas have modified their behaviour – instead of continuing around the south tip of Baja California into the Sea of Cortez where there is huge fishing pressure on them, I wonder if these highly intelligent animals have learned to turn south at Cabo San Lucas for the safe and mostly protected waters of the Revillagigedo archipelago?

Weather: Partially overcast, air temperature 78°F, seas 5 – 7ft dropping to 4 – 5ft, winds from the north at 10 knots.

Water: Water temperature of 72°F. Visibility 100 feet.