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Mobula Munkiana – The Secret of El Barril

Mobula munkiana swirl beneath our boat in a mass aggregation, and leap from the water in an array of fantastic arial displays. Photo: Amber Jackson
Mobula munkiana swirl beneath our boat in a mass aggregation, and leap from the water in an array of fantastic arial displays. Photo: Amber Jackson

Clap, slap, clap clap clap! Mobula munkiana, also known as “Munk’s Devil Ray” explode out of the water around us like popcorn. Each, about the size of a coffee table in diameter, they leap out of the water and flap their wings as if they were able to take to the sky and fly like birds, before landing in an almost comically exaggerated bellyflop. This unique landing has been coined, “The Tortilla”, for the flat orientation of their bodies at re-entry.

As I peer into the water below our expedition boat, thousands upon thousands of the rays glide by silently like a massive parade of synchronized soldiers. Flickering amongst the manta-like bodies of the Mobula munkiana, several other species are observed, sea lions (lobos del mar), green sea turtles (tortugas de mar verde), sharks (el tiberón), yellowfin tuna (Jurel de Castilla) and surprisingly several members of another species of ray, the Golden Cownose. Swimming in the mass aggregation beneath us, they create a whirling orchestra of marine life. We have just drifted into a massive feeding frenzy.

National Geographic Emerging Explorer Asher Jay captures one of several arial displays witnessed that day. Photo: Patty Elkus
National Geographic Emerging Explorer Asher Jay captures one of several arial displays witnessed that day. Photo: Patty Elkus

Welcome to El Barril. El Barril is one of a precious few places remaining in the Sea of Cortez that has survived man’s touch relatively unscathed. It is clear that we have arrived at one of the most biologically diverse and abundant bodies of water on planet earth. However this area, like so many others in Baja, is threatened due to trawling, development, and pollution. Fortunately, there are those who have spent their entire lives in this place, and, witnessing first hand the growing threats, have decided to assume the role of eco-guardian.

Mary Jameson is a force to be reckoned with. Amazonian in stature, beautiful and passionate, she is one of several such eco-guardians in this area that has made protecting this sacred wild place her mission. She, along with her brother James Jameson, who has over the past twelve years sponsored University of California San Diego (UCSD) students to conduct field research project studies with the El Barril fishing community, believe that there are still some wild, raw and beautiful places left on this earth, but realize that without action, they may cease to exist. Trawling is of particular concern in this seemingly remote area. At the end of each expedition day, we stroll the beaches identifying the whorled shells that have washed ashore, sadly however, they are not all we find. On these walks we also encounter the discarded entrails of the trawler’s bycatch; the broken bodies of dolphins and large glittering roosterfish are just a handful of the casualties we witness. A profound shift in the balance of the local ecosystem is occurring right before our eyes, evident upon the shifting sands of the beach.

Thousands of Mobula munkiana glide beneath our boat in synchronized unison. Photo: Emily Callahan
Thousands of Mobula munkiana glide beneath our boat in synchronized unison. Photo: Emily Callahan

Over the course of an hour, Mobula munkiana continue to leap about our boat, often in succession of one, two, even three aerial displays. Very little is known about the high-flying Munk’s Devil ray, and researchers continue to debate the meaning behind their spectacular aerial behaviors. Walter Munk, the “Einstein of the Ocean’s”, and for whom the rays are named, has hypothesized that the distinct and clearly audible slapping sounds that occur upon the ray’s landing back into the ocean may be used as a form of communication. Still others have guessed that perhaps the behavior is more practical, and used as a way to remove parasites clinging to their bodies, or, it may simply be a display of excitement. Our team developed our own hypothesis based on our observations of the feeding frenzy we witnessed that day on the water. Is it possible that the rays used the distinct slapping sounds to purposefully herd, immobilize and frighten its prey? These include a myriad of mysids, zooplankton, and small schooling fish. For indeed other species that display collaborative behaviors, such as dolphins and orca whales, exhibit similar displays while hunting in packs, powerfully slapping their tails to create a sound wave to stun their prey.

One thing about this mysterious and acrobatic ray remains clear, we still have so much to learn and we may be racing the clock as its very existence is threatened. The ray’s unique tendency to school in mass aggregations has resulted in a high mortality rate, a devastating result of local gill and trawl net fisheries. It’s limited geographic range and low reproduction potential, (a mature female may only birth one pup in her lifetime), further serves to compound this species’ vulnerability.

Hundreds of miles away from the nearest city, guarded by towering saguaro cacti, El Barril is wild and remote. Historically, the oceans have been El Barril’s primary source of economic sustenance, but their fisheries are rapidly being depleted. Our team recognizes that this village, like so many others, is in a race against time, and must seek new and innovative forms of ocean management if it is to preserve its legacy. Under the watchful eye of our local guide Luis, and Mary Jameson, our expedition’s leader, our team included Amber Jackson and myself of Blue Latitudes; Asher Jay, a National Geographic Emerging Explorer; Patty Elkus, a board member of the Scripps Institution of Oceanography; and Katie Walter. We had set out on a journey of exploration to uncover the secrets and beauty that is El Barril and the Sea of Cortez. Each team member brought to the expedition a unique perspective and background, but all shared a common passion to conserve our wild blue oceans and to bear witness to a future hanging in the balance.

Several Members of the Expedition Team. From Left to Right: Mary Jameson, Education Endowment Committee member for the Birch Aquarium at Scripps Institution of Oceanography; Patty Elkus, board member of the Scripps Institution of Oceanography, Mission Blue, and TBA21 Academy; Amber Jackson and Emily Callahan, co-founders of Blue Latitudes
Several Members of the Expedition Team. From Left to Right: Mary Jameson, Education Endowment Committee member for the Birch Aquarium at Scripps Institution of Oceanography; Patty Elkus, board member of the Scripps Institution of Oceanography, Mission Blue, and TBA21 Academy; Amber Jackson and Emily Callahan, co-founders of Blue Latitudes