Scientific research

As part of our tour with the “Mozambique Experience”, we had the opportunity to spend time with the two marine biologists who are studying the Whale Sharks and the Manta Rays in the area. Andrea Marshal, originally from the USA, has been studying the Mantas here for more than three years. Simon Pierce, from New Zealand arrived in October of last year to study the Whale Sharks. Their research is being coordinated with the University of Queensland in Australia and is being supported in part by Casa Barry Lodge, Tofo Scuba and the recently formed Mozambique Manta Ray and Whale Shark Trust.

When we arrived, Simon had been in Tofo for a little over 5 months, and had already established a photo ID database of more than 200 individuals, which is remarkable when compared to other Whale Shark research projects in the world. What drew Simon to base his research here in Tofo was partly due to the abundance of Whale Sharks, but also due to the fact that they could be found, and studied, here year round. “That’s one of the things that makes Tofo so incredibly unique for research”, says Simon. “No where else in the world have we found a place that you can see Whale Sharks regularly at any time of the year – and in greater numbers than all but a few destinations.”

Simon’s research has so far indicated that the Whale Shark population in Tofo is migratory, with most individuals not appearing to stay in the area for more than a couple of weeks. “What we are seeing here is mostly juvenile and young adult Whale Sharks, with most being between six and nine meters in length. The majority up to now has been immature males, but we will see what happens during the rest of the year.” With the enormous amount of plankton in this area, it appears that the Whale Sharks approach the coast south of Tofo specifically to feed. During our trip, we were able to witness an uncommon occurrence in Tofo, when something in the plankton was drawing both the Mantas and the Whale Sharks in to feed together.

With Whale Sharks only protected under CITES while they are migrating, and increasingly under pressure from shark finning and commercial and local fishing, Simon hopes that he will be able to work together and co-ordinate with other research programs in the Indian Ocean and elsewhere to try and establish migratory routes and regional populations. “So little is known about Whale Sharks and the research is still in its infancy, but we need to work now to get protection measures in place or the species is in serious trouble”. Simon hopes that in the near future advancements in satellite tag technology will bring down the cost and increase the effectiveness. For now though, photo ID is the best option and it is hoped that soon an international Whale Shark photo data base will be established, something that even recreational divers with cameras would be able to contribute to.

Andrea Marshal’s Mozambique Manta Research program was set up more than three years ago, and what she has so far learned about the Mantas in the area is extraordinary. One of things that we had noticed almost immediately, other than the fact that these Mantas appeared to be bigger than Mantas we had seen in other parts of the world, was that most of them appeared to have large bite marks on them. What Andrea’s research has clearly indicated is that the Manta population in this region is the only one in the word where a significant majority of the individuals have one or many shark bite wounds, some old and scarred and some being very fresh.

These wounds, according to Andrea, are probably a contributing factor to these Mantas spending a great deal more time being cleaned than Mantas that have been studied elsewhere. With tags and listening stations, Andrea has been able to document behavior, with some individuals spending hours each day being cleaned. “Cleaning is extremely important to the health of a Manta Ray”, says Andrea, “What we see here is multiple individuals, up to 10 or 15 at times, cleaning together, taking turns on station in a very orderly and social manner”.

Like the Whale Sharks, Manta Rays are seen in the area year round, making Tofo ideal for research, and also making it the only place in the world where Whale Sharks and Mantas can be seen at any time of the year.

Andrea’s Photo ID program has so far documented more than 350 individuals, making it the single largest scientific Manta photo database in the world. Like Simon, she is also hoping to begin coordinated and cooperative efforts with other researchers in the region and is hopeful about the use of satellite tags in the future. “Right now, we can only guess where these Mantas go when they are not inshore on the reefs”, she says. “What we are also hoping to learn, is that if this is a strictly regional population that has not genetically mixed with other populations for a significant period of time, have they evolved differently, and if so, enough to be declared a new species.” Andrea is currently awaiting the results of genetic testing on tissue samples, and if they support her hypothesis, she will be presenting the Mantas of Mozambique as a potentially new species at the International Shark and Ray conference in the States this year.