Roughly 250 miles off Mexico’s Pacific coast,
rugged islands rise steeply out of the sea. It’s one of the most spectacular places
in the world. This is the remote Revillagigedo Archipelago. It’s just absolutely magical. There are four islands in the Archipiélago
de Revillagigedo, known as the Socorro Islands. So, there’s San Benedicto, Socorro, there’s
Clarión, which is the farthest out, and then there’s Roca Partida. They’ve had their origin as volcanic structures
rising from the seafloor and they were all active volcanoes at one time. And those islands are not inhabited by people,
and not frequented by weekend sailors, they’re too far away. These far-flung islands are popular with die-hard
scuba divers who visit on liveaboards. It’s a bucket list dive site. The divers come for once-in-a-lifetime encounters
with the gentle giants that travel the open ocean. They’re like giant airplanes that start
to fly in. They are so big, so elegant, and so beautiful. Diving with the mantas is indescribable. I can even say that it’s a spiritual experience. The mantas, they’re warm and they’re friendly
and interactive and they like to feel your bubbles on their belly and they react to it. I’ve studied mantas both in the Galapagos
and at Cocos and while they’re beautiful and unique in their own way, they don’t
show the kind of interest in people and the interaction that we’ve experienced here. This unique behavior led the United Nations
Educational, Scientific and Cultural Organization, or UNESCO, to declare the Revillagigedo Archipelago
as a World Heritage Site in 2016. And it isn’t just giant mantas that frequent
the islands. You see seven different types of sharks: white
tips, silvertips, blacktips, silky sharks, hammerheads, tiger sharks, Galapagos.Revilla
is a special for the numbers of different species in very small area. Even though these islands are relatively small
they provide a fair amount of protection and there’s an abundance of food. The islands’ distinctiveness has earned
them the nickname “Mexico’s little Galapagos.” There are some animals found at the Revillagigedos,
the fish, are found nowhere else in the world. That uniqueness makes them intriguing to biologists
because you’re essentially seeing evolution in action. What can scientists learn from the ocean giants
that come here? How do they use these island habitats? Major funding for this program was provided
by the Batchelor Foundation, encouraging people to preserve and protect America’s underwater
resources. And by: Diver’s Direct/Emocean Sports, inspiring
the pursuit of adventures and watersports; The Do Unto Others Trust; The William J. and
Isobel G. Clarke Foundation. And by the following: Lady Suzanna P. Tweed
and Carleton Tweed Charitable Foundation; Skip and Diane Day. It takes more than a full day’s journey
from Los Cabos on the Baja peninsula to reach the archipelago by boat. Dr. Robert Rubin, who heads the Pacific Manta
Research Group, first encountered mantas in this remote island chain in the late 1970s. I’ve always been intrigued by mantas in
large part because there was no scientific knowledge really of note. I think they’re one of the most beautiful
designs I’ve ever seen. And I think that it’s important to be intellectually
intrigued and also emotionally involved in one’s work. The first work that was undertaken by mantas
at least in the Pacific, that I’m aware of, was the work that we started in the Sea
of Cortez, and to a lesser degree at the Revillagigedos, and it was mostly just natural history. I thought, at the time, that they were very
rare and that most people thought that also. If you saw one, it was pretty exciting. In those early days, Dr. Rubin focused most
of his manta research on the Sea of Cortez. And they were abundant at lots of sites and
then gradually they were less abundant and this correlated with the abundance, or lack
of, the big sharks: hammerheads, makos, others. I spent most of a year in the early nineties
looking for them at the sites that I had seen populated by large numbers in the past, and
in that year of searching I didn’t see a single manta. I didn’t see them in the ocean and I didn’t
see them in the fish camps, which you’d occasionally see where they’d been caught. The last manta that I saw in the Sea of Cortez
was in the mid-eighties. Years of heavy fishing pressures had decimated
the number of mantas in the Sea of Cortez. The transition to Socorro and the adjacent
islands occurred when we realized that we couldn’t work in the Sea of Cortez any longer
-- they were gone. Oceanic-or giant-manta rays are currently
listed as vulnerable by the International Union for Conservation of Nature. Mantas have been back and forth thought of
as endangered or threatened. We really don’t know, to be quite honest,
because we’ve only started to understand where the populations are. When I first started working on this I was
the only person in the world that was working on them, but now, there are lots of people
that are interested and the assessments are starting to become more sophisticated. The population sizes seem to be larger than
I would have ever predicted but they are likewise isolated in certain regions. Early observations of the animals showed that
individuals can be identified by their appearance. The color patterns of mantas seem to be highly
variable, so we can recognize them individually. There are two color forms, the black morph
is very unusual and rare-er, a beautiful, elegant beast and that animal is often seen
within populations or groupings of chevron mantas, which is a lighter animal with patches
of white on its shoulders and v-shaped designs on its wings and posterior upper body. And then underneath they’re white with black
markings and that seems to be the most common form and in places of the world it’s the
only form that appears. The pattern of the shoulder patches on the
top and to a little bit lesser degree, those underneath, are habitat specific. So, you can see a picture of an animal and
say yes, that picture was taken in Mexico, or that was taken in Africa and so on. And that led to some of the early ideas about
there being different populations. Mantas are found in tropical and subtropical
oceans across the globe. Up until about ten years ago it was thought
that there was a single species of manta worldwide and as more and more people started to study
them we realized that there were some rather significant differences. Mantas are now classified into two separate
species and there may be a third actually now in the in the Atlantic, but the two that
are well defined are referred to as the oceanic manta and the reef manta. The oceanic manta is larger in size and it
seems to be more associated with colder, nutrient rich, water that is associated with offshore
islands and seamounts, open ocean habitats. The reef manta is about 15% smaller. It has somewhat different markings and it
is more associated with warmer water and reefs. Over the years Dr. Rubin and his team have
put together an extensive photo identification guide that helps them keep track of individual
animals. We established a photo catalogue that now
has about thirty thousand plus photographs in it. Divers visiting the islands are encouraged
to submit their images to help with the research. All sorts of folks from all sorts of different
walks of life in the world send us pictures and they have been instructed or asked to
give us at least one perfect image of the animal’s belly and boy we’ve gotten some
great photographs. We identify them based on five different characters
in the markings. We can then match them, and this is kind of
a key and you do it by somewhat of a process of elimination, it has these markings, it
does not, if it does not you go over here, if it does you can follow up. And we keep track of when we’ve seen it
where we’ve seen it and so on. And so, we know about a little over six hundred
different animals, and about 250 we’ve seen more than one time. We see new ones on every trip, so it just
means that the population is growing or we’re learning more about it. Accoustic tags make it possible to track the
animals’ movements. Those tags are attached to the mantas themselves
with a small dart, right underneath the skin. They have a battery life of about a year. And they come off the mantas fairly readily. The acoustic tags send out sound signals that
are recorded by underwater receivers. They’re extended from the seafloor by a
float and they’re listening for the tag, they’re also recording time of day and water
temperature. So, we know when the animals are present and
when they’re absent. Unfortunately, the tags have a very limited
range, a little over a kilometer maybe. They come into a location around an island
and they may be around for twenty minutes or thirty minutes and sometimes for a couple
of days. And then they’re gone. And then maybe we’ll pick them up at another
island. We know that they’re moving between islands. Sometimes the same day, so it’s not uncommon
to see an animal at one site and then the next morning see it at the new site, which
is separated by maybe sixty kilometers or so. So, they can swim fairly quickly from place
to place. The receivers are located throughout the archipelago,
as well as in the Sea of Cortez and along parts of Mexico’s Pacific coastline. They move between San Benedicto, Socorro and
Roca Partida and they’re moving back and forth into the southern Sea of Cortez and
maybe up north as well. We’re starting to see them in places that
I have never seen them in the past. They’re not abundant, but they’re here
and there, which is very encouraging. We also see them moving from the Revillagigedos
south into Bahía de Banderas, which is around the resort city of Puerto Vallarta, and even
farther south than that. So, we think that the population in the islands
is acting as a recruitment site. And that’s very encouraging, because if
they’re protected now in the Sea of Cortez and other places it looks like they’ll repopulate
it. And we’re excited about that potential. Dr. Rubin shares the receivers with Mexican
scientists who study other animals. One of them is Frida Lara Lizardi, a Ph.D.
candidate who works for Pelagios Kakunjá, a non-profit dedicated to the recovery of
marine predators through science-based conservation. My Ph.D. is about the distribution patterns
of the sharks and first I started especially in Revillagigedo, or Socorro Islands, and
then as the years passed I also study other marine reserves like Cocos, Malpelo and Galápagos. So, I’m looking for the connections between
the marine reserves in order to protect some species of sharks like Galapagos and silky
sharks. Frida began her research in the archipelago
by setting up baited cameras on various dive sites. I wanted to see all the sharks that are around
the area and I found eight species. Frida is also using acoustic tags to study
the movement of sharks. We have been following the movements of 23
Galapagos sharks and 24 silky sharks that has been tagged since 2008. The research shows that the sharks travel
back and forth between the islands, putting them at risk of being caught by fishermen. Shark populations have been on the decline
in Mexico, and in 1994, the Mexican government established the islands as a biosphere reserve. Currently there is a no take zone in place
around each island that extends out for twelve miles from the shore. But scientists argue, that isn’t enough. For us, it was very important to prove that
the sharks are doing this movement between the islands, because there are some areas
between the islands that are not fully protected. So, all the fishing boats can go there and
exploit tuna and also some sharks. Not just Galapagos and silky sharks other
sharks like tiger sharks and silvertips are also using these three main islands and they’re
moving between these places so we think if we protect this areas we can protect a lot
of species. The proposal is to cover a bigger area, around
the islands, so doing that we can cover a triangle between the islands and then protect
the sharks. Using their research findings, Pelagios Kakunjá
is working closely with Mexican authorities to extend the protected areas. Past research has shown that marine reserves
that are closed to fishing don’t just allow local populations to recover, but they can
actually create a spillover effect into unprotected areas. Socorro islands, or Revillagigedo, are very
important because in Mexico it’s the only place that you can find this number of species. I think as Mexican we have the responsibility
to protect this place and to show that it’s important for us. One of the main reasons that I feel that Revillagigedo,
or the Socorro Islands, need to be protected is because it is so remote and an issue we
have out there is the illegal fishing. And so, we need to make the policy holders
understand that they need to have vigilance all the time at the Revillagigedo Islands. Mantas, too, are affected by fishing pressures. We lose so many of them to fishing, sometimes
intentionally killing them, sometimes killing them by accident, stuck in the nets. While mantas are now protected in Mexico,
they are killed in other parts of the world for their large gills, which are used in traditional
Chinese medicine. Mantas have very large mouths and they use
modified gills to filter their food out of the water. One of the major mechanisms that you see in
mantas is the modification of these pectoral fins into feeding devices that we call cephalic
fins. They look like large spatulas coming off the
sides of the face, around the mouth and those are used in feeding. When the mantas swim in the open water and
they’re not feeding they roll them up like a newspaper and it reduces the drag on the
swimming motions. But, when they feed they open them and drop
them down and around the mouth like large scoops and open the mouth and with them they
create a vortex of water that cycles into the mouth. Mantas filter large amounts of water to feed
on tiny animals called zooplankton. This is what got Ph.D. student Tania Pelamatti
interested in studying mantas. Two years ago, I had the opportunity to go
to the Revillagigedo Islands for the first time and when we jumped in the water and there
were those beautiful animals swimming elegantly in the water, I completely fell in love and
I said I want to study them, I want to work with mantas because I think they’re the
most beautiful animals I have ever seen. This is my dream job. Tania is curious if the filter-feeders are
negatively impacted by plastics in the water. I was thinking about the quantity of water
they filter every day and so during all their long life how many plastics will they get
in contact with and how can they affect them? The islands’ beaches are generally off-limits
to visitors, but Tania obtained a special research permit from the Mexican authorities
to go on land and collect plastic trash that washed up on shore. 300 miles from the coast there are big quantity
of plastics, so not even a small island in the middle of the Pacific is free from this
pollution. Winds and currents can transport plastic trash
over long distances out into the open ocean, far from their places of origin. It’s estimated that between eight to 30
million tons of plastic trash enters the ocean each year, making it one of the most common
pollutants in the sea. We found 28 shoes, it was clear-clear that
they had traveled a lot and they were losing pieces during their time in the ocean. We collected also 51 bottles, and we were
looking at the bottles and we saw that three of them were from Japan. So, it’s the proof that plastics can reach
every place on earth. It was pretty sad to find all this plastic
objects in such a remote beach. While large trash is a problem, Tania is particularly
interested in microplastics - tiny fragments that are less than five millimeters in size,
which could easily be ingested by the filter-feeding mantas. Manta rays, the size of their food is the
same of microplastics. Everyone knows about whales eating plastic
bags or bottles or big nets that can entangle animals, but very few is known about the importance
and the effect of microplastics on animals. People don’t think about it because you
cannot see them. To detect these microplastics, Tania conducts
a number of experiments. We have been doing samplings with the special
net that is made to collect the first centimeters of water from the surface. And so, we’ve been collecting microplastics
doing 30 minute trawls so that we can evaluate the density of microplastics in the surface
zone. Microplastics come from a variety of sources. Tiny plastic granules are added as exfoliants
to cosmetics and as industrial abrasives used for sandblasting. Then there are virgin plastic production pellets
and small fragments created by the breakdown of larger plastic trash. Tania also collected sediment samples on San
Benedicto Island, to see if microplastics are washed up on the beach. Scientists are concerned about the potential
health impacts these plastic particles might have on animals that ingest them. As plastics deteriorate they leach toxic chemicals
like BPAs and others. In addition, persistent organic pollutants,
which are present in low levels in the water, will stick to the surface of plastic trash
and accumulate there. These contaminants include PCBs, PBDEs, pesticides
like DDT, and other toxic chemicals known to cause serious health impacts ranging from
endocrine disruption to cancer. So, there is the double danger of microplastics,
they are the pollutants itself that plastic leach, and the pollutants that are adsorbed
during their staying in the ocean. The main problem for manta rays is that they
can live for more than 30 years, so during this long life, they can accumulate a lot
of those pollutants. And so, filtering plastics for so many years
it can make damages at many levels. Tania also received special permission to
collect small tissue samples, which she will analyze to see if the toxic chemicals are
present in the mantas’ bodies. She is comparing populations of mantas in
the remote Revillagigedo Archipelago to the heavily populated Bay of Banderas on the Mexican
coast. I want to see if those manta rays of coastal
region are more or less impacted by microplastics than Revillagigedo’s ones. I have found plastics in both Revillagigedo
Islands and Bahía de Banderas and so we’re going to see what we’ll find in the biopsies. Once you meet manta rays for the first time
you have a special connection with them. When you look into their eyes you have the
feeling that they are such intelligent animals and that we have to do something to protect
them. Much is still unknown about mantas. Manta rays are thought to be the most evolutionarily
recent and advanced form of living elasmobranchs, the class of cartilaginous fishes that includes
sharks, skates and rays. They have a number of features that make them
more mammalian like than fish like. One of them is the way young are raised in
utero and their brains are quite a bit larger than you’d expect for an animal of that
size. Mantas are one of only a few animals, and
the only fish, known to recognize themselves in a mirror. There’s really a suggestion of some kind
of consciousness. I hope so, I would like to believe things
like that even though it’s not good science. Mantas have charmed divers and intrigued experts
like Dr. Rubin for decades – providing a glimpse into a mysterious underwater world,
where much is left to explore. I’ve loved every minute of it every day. I haven’t had very many bad days at sea,
and in part there are days where we get no data and we have nothing to show for ourselves
except the windmills of our mind and I have been blessed with big windmills, and mantas
are big parts of those spinning blades. Major funding for this program was provided
by the Batchelor Foundation, encouraging people to preserve and protect America’s underwater
resources. And by: Diver’s Direct/Emocean Sports, inspiring
the pursuit of adventures and watersports; The Do Unto Others Trust; The William J. and
Isobel G. Clarke Foundation. And by the following: Lady Suzanna P. Tweed
and Carleton Tweed Charitable Foundation; Skip and Diane Day.
