-: Good evening.
We're pleased to have you join us
for our annual Seaside Chat speaker series
about Ocean Topics Associated with Flower Garden Banks
National Marine Sanctuary, and the Gulf of Mexico.
This year, we're also part of
the National Marine Sanctuaries Webinars series
hosted by NOAA's Office of National Marine Sanctuaries
as well as part of the OneNOAA Science Seminar Series.
During the presentation,
all attendees will be in listen only mode.
You are welcome to type questions for the presenters
into the questions box in the bottom of the control panel
on the right hand side of your screen.
This is the same area you can let us know about
any technical issues you may be having.
We will be monitoring incoming questions
and technical issues,
and we'll respond to them as soon as we can.
We are recording this session and we'll post the recording
to the National Marine Sanctuaries
and Flower Garden Banks National Marine Sanctuary websites.
We will notify registered participants via email
when these recordings are available.
And for those of you who are educators,
we have provided a Manta Mysteries activity
in the handouts pane of the control panel.
I am Kelly Drinnen, Outreach Specialist
with Flower Garden Banks National Marine Sanctuary
and I'll be facilitating today's Webinar
from Dickinson, Texas.
Leslie Whaylen Clift,
our Constituency Affairs Coordinator is also
joining us from Galveston, Texas.
Leslie will be helping me with
the back end administration of this Webinar.
NOAA manages a system of marine protected areas
called national marine sanctuaries
that are found throughout the US.
National marine sanctuaries are special ocean areas
set aside by Congress to protect for future generations.
They're like national parks and national forests
yet underwater.
The National Marine Sanctuary system consists of
15 marine protected areas that encompass more than
600,000 square miles of marine and great lakes waters
from Washington state to the Florida Keys
and from Lake Huron to American Samoa.
The system includes 14 national marine sanctuaries
and Papahānaumokuākea
and Rose Atoll Marine National Monuments.
If you're doing the math, that adds up to 16.
That's because the Rose Atoll Monument is inside
National Marine Sanctuary of American Samoa.
NOAA Office of National Marine Sanctuaries
is mandated to conduct research, monitoring,
resource protection, education, outreach, and of course,
management of America's underwater treasures
to preserve them for future generations.
National marine sanctuaries are also living classrooms
where people can see, touch and learn
about the nation's great lakes and ocean treasures.
Today's Seaside Chat Series is hosted by
Flower Garden Banks National Marine Sanctuary,
the only national marine sanctuary in the Gulf of Mexico.
This sanctuary consists of three banks
or small underwater mountains that are home
to some of the healthiest coral reefs in the world
and amazing algal-sponge community
and deep reef habitats featuring
an abundance of black coral.
In January of this year, the sanctuary also published
a final rule for expansion which will add portions
of another 14 reefs and banks to the sanctuary.
Today's presentation has both a global and local focus.
Manta rays around the world are some of the most
poorly studied ocean giants.
They're threatened by fisheries, ship strikes,
habitat degradation, and a suite of other human impacts.
Many populations around the world are in decline,
and the species was recently listed under
the US Endangered Species Act.
Closer to home, an undescribed species of manta ray
has been hiding in plain sight
at Flower Garden Banks National Marine Sanctuary.
What are these rays doing off the coast of Texas?
What are scientists learning about this population?
And what remains to be discovered?
Today, we welcome Joshua Stewart to answer these questions.
Joshua is Associate Director of The Manta Trust
and he will talk about the plight of these mysterious giants
and what we are learning about populations
in the Gulf of Mexico.
Josh has been studying manta and devil rays since 2010
and helped found The Manta Trust in 2011.
His work covers a range of topics related to the biology,
ecology and conservation of manta and devil rays.
He first started working with the team
at Flower Garden Banks National Marine Sanctuary
as a NOAA Nancy Foster Scholar during his PhD studies.
In addition to his work with mantas,
Josh is a research associate for
The NOAA Marine Mammal and Turtle division,
where he studies the population dynamics
of several whale species.
Welcome, Josh.
-: Thanks Kelly.
-: And there we go. Handing over the controls.
-: Let's see if we can get it working.
How's that look?
-: That looks good. We're ready.
-: So that headshot that you had of me is outdated.
I've had really short hair for years now
but the pandemic has (inaudible) things.
It's back out to long hair.
I don't know. That says something.
Wow, thanks everybody for being here.
It's pretty cool to see 500 people online.
I guess that might also be a sign of the pandemic.
People are running out of things to do at home,
but it's cool to see you all here
and hopefully you enjoy this talk
and all these fun photos and videos and facts about mantas.
I'll just introduce myself a little bit more.
I've been working with these really amazing animals
for almost 11 years now.
And I've been really, really privileged
to get to spend a lot of time with them
in the wild, in the water.
They're really amazing animals to be around.
The field work is definitely one
of my favorite parts of the job.
And I've also been missing that quite a bit this past year,
a lot more time behind the computer than I usually like.
So hopefully this talk will be a little bit
of an exciting trip for all of us, myself included
since I'm missing these field expeditions myself.
So they're really fantastic animals.
I've gotten to do things like tag them
to figure out where they go,
use a bunch of different methods to figure out
what habitats they use,
what they eat.
Some interesting things like sticking cameras on their heads
with suction cups has been some of the more unusual
and exciting work that I've gotten to do with them.
And just get to be around them and observe some
really unique behaviors and appreciate them
for these really amazing
and also mysterious animals that they are.
So my goals for the presentation today are to give all
of you some basic information about manta rays.
Get you up to speed on what we know about them,
some basic facts.
And then I also wanna share some of the work
that I and others have been doing with these animals
that have resulted in some unexpected
surprises about their ecology and biology
that we may not have otherwise known.
And so we've discovered a lot of things about these animals
over the past decade.
As Kelly mentioned, they used to be and remain
one of the most poorly studied
of the really large marine megafauna in the oceans.
But we have learned a lot in this last decade.
There's been a lot more focused scientific attention,
and I'm gonna focus on a few of those things
that we've learned that I think are most interesting.
And then I'm gonna circle back around
to the Flower Garden Banks and how these new discoveries
tie into what we're learning about
the Flower Garden Banks mantas.
-: [Kelly[ Are you ready for your first poll question?
-: Yeah, let's do that first poll question.
So thank you, Kelly.
I can't see these poll questions.
So Kelly's gonna send this one out.
I wanna know how many of you have actually gotten
to see a manta in the wild.
And you can go ahead and answer that
and I'm just gonna continue presenting
and then maybe Kelly, you can, oh, I do see.
There's a poll up there.
Kelly: Have you ever seen a manta ray in the wild?
Please make a selection on the screen
and we'll give it about 30 to 45 seconds
for people to respond and then we will close the poll
and share the results with Josh.
-: Great. So I'm gonna keep on talking
and then in a couple of slides,
I'll check back in and see where we're at. How's that?
Kelly: Sounds good.
-: So one of the things that obviously intrigues people
about mantas most is their size.
These are really enormous animals.
The biggest of the manta is the oceanic manta,
they can reach sizes up to a maximum
of close to 25 feet across, which is enormous.
And they're so gentle. They're so friendly.
They don't have big teeth or anything.
They're not aggressive.
They're really gentle giants.
So they're one of these unusual, enormous animals
that you can really spend a lot of time,
pretty close up with.
They're really interactive and they engage with
divers quite a bit.
And I see that just over half of the audience
or at least half of the respondees have actually seen
a manta in the wild.
So that's pretty cool.
And for those of you who haven't,
hopefully you can maybe experience some of the odd
that we do when we get to see them in the wild
just from these photos.
So from this photo, you can see first just how big they are
but also how close you can get to them.
They will actually approach you in the water.
And they've got these really enormous brains.
They've got the largest brain of any fish
and one of the largest brain to body mass ratios
which tells us a little bit about
their potential intelligence levels.
And you can really feel that
when you're in the water with them.
They spend a lot of time really checking you out,
investigating you, looking at you eye to eye.
They're in a larger group called the manta and devil rays.
And they're not the only ones,
we hear probably most about the mantas.
And we also know the most about the mantas,
partly because they're so popular with dive tourists.
And we know where we can find them for the most part.
But there are a lot of other species in this
manta and devil ray group or the genus Mobula.
Some of them are actually quite small.
So not all of the manta and devil rays
are these enormous animals.
It depends, they are between nine and 11 species.
And I hope that this will highlight to you
how much there still is for us to learn about these animals.
We can't even tell you how many species there are right now.
It changes every time somebody does a new genetic analysis.
Every few years, it gets updated and we change the number
of manta and devil rays that there are.
So we think of the oceanic mantas
as these real ocean giants.
And there are a couple of other manta species
but we do get some of these
really small pygmy devil rays as well,
which sometimes don't get any bigger
than about three feet across.
So a lot of diversity in size
and a little bit of diversity in habitat use as well.
But one thing that all of these guys share in common,
I'll note that I can't see what slides are coming
because I'm in presenter view or I'm not in presenter view.
So if I accidentally start on another topic
and then I find out that I actually had another slide here
I'll just about face.
There are two different species of manta rays
on top of about eight or nine species of devil rays.
We've got the oceanic mantas,
which as their name suggests they live in these
more open ocean, pelagic, open water habitats.
And then we've got the reef manta rays.
And these ones, they're a little bit more resident
to reef habitats in the tropics.
So they tend to stick a bit closer to shore.
And most people who have gone diving
or snorkeling with mantas have probably seen reef mantas.
And until 2009, we actually did not know that
these were different species.
They were also hiding in plain sight
because they're not often together in the same place.
So they look similar enough that it was confusing
and we didn't learn until 2009
that those are two separate species.
Once you know what you're looking for,
they're pretty, relatively easy to tell apart.
They've got some visual characteristics
that are pretty consistent across species.
Oceanic mantas always have a black mouth,
reef mantas always have a white mouth.
And then these little epaulets or shoulder patches
are very different between the species.
And there's not gonna be a test on this or anything.
You don't have to remember this.
This is just to say that once you know
what you're looking for, it's pretty easy to tell
if you're looking at an oceanic manta or a reef manta ray.
We also know from genetic evidence that in the Atlantic,
the Caribbean and the Gulf of Mexico,
there's a third manta species.
And it hasn't yet been described,
for now we're calling it
the Caribbean or the Atlantic manta.
It's not an official species, but we do know
from this genetic evidence that these little orange dots
in the bottom right corner are genetically very,
very different from either reef mantas in red
or oceanic mantas in blue.
And then there's this one really curious little guy
who's hanging out between oceanic mantas
and Caribbean mantas.
And I'm gonna come back to that,
I'll circle around to that at the end of the talk.
I'm leaving these little cookie crumbs
and then we're gonna tie them all together
when we start talking about Flower Garden Banks.
There we go.
So now what's so interesting about this third species
is that visually it has a huge amount of diversity.
And that makes it really, really hard to be able to say,
am I looking at an oceanic manta?
Am I looking at one of these Atlantic's/Caribbean mantas?
Because there's actually more of this.
We call it morphological diversity,
more diversity in the physical characteristics
and the coloration patterns within this species
than there is between the oceanic and the reef mantas.
And that's one of the reasons that
there's not a formal description.
This isn't an official species yet.
'Cause it's been really challenging to find features
that uniformly can distinctly characterize it
as this species versus an oceanic manta let's say.
So we know that genetically they're distinct,
but morphologically we're still trying to figure out
exactly what we can use to characterize
these different species.
So that is the mysterious third species that we know exists
but we're having trouble identifying who is hanging out
in the Gulf of Mexico and the Caribbean and in the Atlantic.
One thing that all of the manta and devil rays
have in common is that they feed on zooplanktons.
So they're filter feeders,
which means that they open up their gigantic mouths
and they filter huge amounts of water.
They have these really, really cool specialized,
we call them gill rakers.
They are these cartilaginous structures
that surround their gills.
And they use those as a sieve to filter out
mainly zooplankton from the water.
So they don't have big teeth,
they've got these kind of like microscopic
sandpapery teeth on their jaws.
But they are totally harmless if you're bigger
than the size of a small fish.
If you're a zooplankton, they're a horrible predator.
But for those of us who are big enough to escape
their mouths, they're gentle giants.
So if you can imagine when you see a manta
they look like these flat disks
that are really hydrodynamic.
But as soon as they open up their gigantic mouths,
suddenly it's like dragging a big sea anchor around.
And so that actually costs them a lot of energy
in order to feed with an open mouth.
And so they've developed all these different
strategies to maximize their foraging efficiency.
And one of them is these big lobes,
we call them cephalic fins, that unroll.
So they look like horns when they're all rolled up
and then they unroll and they can help the manta channel
water and plankton into its mouth.
So that, on the individual level, allows them
to help maximize that forging efficiency.
But there are also lots of these really interesting
social behaviors where for example,
they'll stack up in a line
which you're looking at on the left here.
One manta above and behind the next one.
And the reason they do that is because if you're a little
zooplankton and there's a big manta bearing down on you,
there's not much you can do to escape that manta.
But you can jump pretty quickly in the water.
You can make a really rapid jump up or down.
And so the mantas position themselves
so that if the zooplankton jumps to avoid the manta
in front of it, it just gets scooped up into the mouth
of the manta behind it.
We also see a really famous manta feeding behavior,
these barrel rolls.
And this is where they'll find a really dense patch
of plankton and just continuously loop
through it again and again.
Again, making sure that they're hitting the richest patch
of plankton to maximize their efficiency.
And then we see some really extraordinary,
social, cooperative feeding behaviors like this one
on the bottom right, from the Maldives, where you can get
up to around 250 of these reef manta rays
all feeding in this big cyclone formation
on these really dense patches of plankton.
So there's some really, really extraordinary
adaptations that they've developed in order to maximize
that feeding efficiency.
So how long do mantas live?
That's a good question and I don't have a perfect answer
for you because one of the only ways that we can tell
how long mantas live is by photographing
or tracking individual mantas across time.
So this particular manta here was seen twice
in the Maldives, approximately 30 years apart.
And there are some records of this where mantas
have been seen with up to 40 or 50 year gaps.
And so we know that they can live
for at least 40 or 50 years.
But we don't know perhaps they could live
much longer than that.
And the way that we can identify these mantas and track them
over time is with these unique spot patterns
that they have on their bellies.
So every manta has its own spot pattern,
we think of them as a fingerprint.
They don't change over time.
So they stay constant from the day
that that manta is born until it dies.
And because they're so unique,
we can, as you see there's a lot of diversity
in these spot patterns.
So once we have a photo of a manta,
if we get another photo of its belly,
we can say with confidence, this is the same manta,
this is a new manta.
Here's the last time we saw it and so forth.
And this photo identification is a really,
really important tool for us.
It helps us track individuals across space,
so if they move over long distances
and we get photos of them in different places
that tells us about how they're moving.
It tells us how long they live,
tells us how many there are in many places.
And a lot of these contributions
actually come from scuba divers,
not necessarily from scientists,
but from recreational scuba divers who see a manta,
who get a a photo of its belly.
They can send that to our database.
And then we can hopefully tell them who that manta is
and include it in our research.
So that's really important because as I mentioned,
one of the only ways that we are able to tell
how old mantas are and how long they live is through
those recaptures or multiple photographs of individuals.
And normally the way that we might do this,
in let's say, a shark species to figure out
how old sharks get,
is if we have a dead shark that washes up
in a fishery or gets caught.
We can take its vertebrae and we can cut a little section
and then we can count basically tree rings,
growth rings in that vertebrae.
And that tells us how many years that shark has been alive.
And this vertebrae is actually
from one of the smaller devil rays.
So some people have had some success with aging
smaller devil rays.
And we know from that, that they can live for
at least 15 or 20 years.
But so far we haven't been able to do this with mantas
because their vertebraes don't calcify enough
for us to be able to detect these growth rings.
So just another example of how mysterious these animals are
and I'll circle back to this again and again.
There's so much about mantas that we just don't know
and that we might not know for a really long time.
And I think that makes them pretty exciting to work on.
So they live for a very long time, 40 to 50 years.
Incredibly these animals give birth
to only one pup per pregnancy.
So to put that in context, a lot of other sharks,
they might have five or 10 pups per litter.
Whale sharks, we think they might have
over 100 pups per litter.
Mantas just have one pup per pregnancy.
And these pups come out fully formed
in these little manta burritos.
So they're already about one and a half to two meters wide.
So about six feet wide when they're born
and they're fully self-sufficient,
there's no maternal care.
They're big and they're ready to go.
And I'm gonna talk about this in the context of
Flower Garden Banks a little bit later as well.
But think about that one pup per pregnancy.
And they take about a year to come to term,
so the pregnancy period is one year.
And mantas don't reach sexual maturity
until they're five to 10 years old.
And there can be gaps in between pregnancies
anywhere from two to seven years,
depending on the species and the location.
So to contextualize that,
that's approximately the same reproductive rate
as an elephant.
And I'll just let that sink in because that is wild
for a fish to have a reproductive rate about the same
as an elephant, extraordinarily slow.
We don't know much about these juveniles.
I don't think there's ever been
a single documented live birth in the wild.
We don't know much about where the juveniles go.
And that has remained a big question mark for us,
which we're starting to learn a little bit about
at Flower Garden Banks.
So hold on to that and I'll come back around.
So quick recap.
We know that mantas are big animals.
They live for a long time.
They've got these extraordinarily low reproductive rates
and separately, as far as we can tell,
they've got pretty small population sizes.
So a few hundreds to a few thousand animals per population,
as far as we can tell.
So if you put all these things together,
we end up with a species that is incredibly vulnerable
to any kind of fisheries pressure.
And sure enough, like just about everything
that lives in the ocean,
there are fisheries for these animals.
Back in 2010, one of the things that really intrigued me
about mantas was that suddenly there were these growing
targeted fisheries for manta and devil rays
where fishers were specifically catching them.
And normally, the meat is not very good quality.
We don't think of them as a target species,
a high value species.
Certainly not for meat in most places.
So it turned out that they were being targeted
specifically for those gill plates,
those structures that allow them to
filter out zooplankton as they're feeding.
And those gill plates were being dried
and shipped to different parts of Asia, but primarily China,
where they were being used as
a pseudo remedy or a health tonic.
And just to show you the scale of some of these fisheries.
This is one stall in one dried seafood market in China.
And those are just bags and bags with hundreds
or thousands of individual manta and devil rays represented.
So again, remember those low reproductive rates
and those very small population sizes.
So these targeted fisheries were really, really concerning.
We knew for sure that they had to be impacting populations,
but, there's this other more persistent threat, as well,
that probably has been going on forever
and is much harder to tackle, which is bycatch.
So bycatch is anything that you catch by accident
when you throw some type of fishing gear in the water.
You might be trying to catch tuna
but you actually end up catching a manta,
and that means that that manta is bycatch.
And it turns out that manta and devil rays' superpower
is their ability to get tangled up
in absolutely every type of fishing gear that exists.
So there are the obvious ones like
gill nets and purse seines where you'd expect to
see a lot of these.
But they also get caught in long lines,
in trawls, just in the wildest places.
So we know that this is also a really big problem.
And then more and more we're recognizing
that things like ship strikes, small vessel strikes,
and these sub lethal impacts like
entanglement in fishing gear
that maybe the manta survives it.
They're also having major impacts on populations
but we don't yet really know
how these are influencing population trends
because they're not occurring.
It doesn't necessarily kill an animal
but maybe it reduces their fitness
and impacts their ability to feed or reproduce.
And these are questions that we don't know quite yet
but we know that they're problems.
So as a result of all these impacts,
we have a lot of different streams of evidence
suggesting pretty significant declines
in manta and devil ray populations.
They're not the best data.
A lot of them are just citing trends
as opposed to true abundance data.
They're pretty data poor species in many regions.
And so it makes it hard to do traditional stock assessments
that you would use to manage fisheries
that are data rich.
So we don't know that much about population status
of manta and devil rays,
but we have a lot of evidence that suggests
they're not doing that great.
And they are probably declining in many places.
So this was the context for my PhD research.
This is what all interested me in mantas.
And one of the biggest findings right before I started
my PhD work was the identification
or the splitting of these two manta species.
So suddenly we went from having
one manta species to two manta species.
And it turns out that pretty much everything
that we had known about mantas came from reef manta rays
because they live on coral reefs.
They're easier to access.
Of course, we knew most about them.
And we knew very little about oceanic mantas.
And it also turned out that most of the manta rays
being captured in these fisheries
were oceanic mantas and not reef mantas.
And we just had these absolutely enormous data gaps
about what oceanic mantas are doing.
Where do they go?
What are their important critical habitats?
And just to give you a sense of that,
this is what we knew about oceanic manta distributions
when I started working on these animals.
We knew that they lived in warmish water
and you could find them pretty much
anywhere around the world.
And that was the extent of
our knowledge about the species movements.
And where an animal goes, where a population goes,
what the extent of a population is,
is really, really important for understanding
how fisheries might be impacting them,
but also understanding how we can most effectively
protect them and whose responsibility it is to protect them.
Is it one country's?
Is it the international communities?
So this was a really compelling topic for me.
I was really interested in learning more
and doing some work to better understand
how these animals are moving around
and how that might affect management strategies for them.
So this is where I think we have another poll Kelly.
Kelly: We do.
-: And I'm gonna ask all of you on the call.
How far you think oceanic manta rays travel?
So it could be across, let's say between ocean basins.
So, 10,000 miles or more.
Maybe 5,000 miles, 2000 miles.
Or all the way down to not very much.
So again, I'll let you all fill those in
and I'm just gonna continue on with my presentation
and I'll circle around in a minute here.
Kelly: Just remember they can't see your slide
when the poll's open.
-: Then take your poll now.
(Kelly laughs)
I feel like I'm going a little slowly here.
When are we done Kelly, or what's the cutoff, 5:30?
Kelly: 7:30 is the end. We still got half an hour.
-: Okay. That should be fine then.
Kelly: Looks like we have 82% have voted.
So we're gonna go ahead and close the poll now.
And the results are,
most people think they travel five to 10,000 miles.
-: Yeah. Okay, great.
Super cool.
So this is what we thought too.
And the reason that we thought this,
is because when you look at any other big animal
that lives in these open ocean environments,
we're talking whales, big sea turtles, sharks,
seabirds, tunas, et cetera.
They move around a ton.
And so this map right here, this is a ton of different
big ocean animals that have been tagged with satellite tags.
And then we can see that indeed many of them
are crossing the entire Pacific Ocean,
traveling thousands and thousands of miles and so forth.
And so we know that these are the same animals
that live in similar habitats to mantas.
Many of them are somewhat closely related to mantas.
And so our assumption was that,
surely without any other information,
mantas are probably doing something pretty similar.
So to do this, I and others we used a variety
of different methods to get at this question
of, "How far might mantas be moving,
oceanic manta specifically?"
So I know that this video probably looks choppy for you.
Apologies, that's one of the downsides of presenting online
but what I'm doing here is deploying
a satellite tag on a manta.
This happened to be in Mexico.
And that tag will stay attached to the manta for six months.
And then after that six month period,
it pops off and it sends all of its data back via satellite
and basically tells us where did this manta go.
And the reason we don't use a tag that is
constantly sharing its position is because
mantas do occasionally come up close to the surface.
They're not air breathing animals.
So a turtle or a whale, you can use something
that more closely approximates like your car GPS,
where every time those animals come up to breathe,
it sends a little signal and we know exactly where they are.
But with mantas and other fishes, we have to use these.
They're called archival tags,
where they collect all the data,
and then they tell us about it after the fact.
Pretty wild that the reaction from the animals
is almost nothing to these big,
chunky tagged darts going into them.
And they're still happy to hang out
and play with you after they've been tagged.
So that's always a good sign. We like that.
And I'm just gonna jump straight into the results here.
So we put on all these tags,
we're waiting to see where they go.
I'm a PhD student at the time
and six months go by and I bit my nails to nubs.
And these texts start popping off
and they start reporting back from a few miles
from where I deployed them.
And that's not what you wanna see as a grad student.
Of course, first thing I'm thinking is,
oh my God, I completely screwed something up.
I've done something wrong.
And then, all the tags over time
just pop off and not a single tag made it more
than about 150 miles from where we deployed them.
And when we looked at what the animals were doing
in between when the tag was deployed and popped off,
sure enough, they were hardly moving at all.
And so these polygons that you're looking at on the maps
they're the purple orange and red polygons.
Those represent all the mantas that we tagged
at each of those three sites,
how far all of the combined mantas moved around.
And the answer is hardly at all.
And so if you look at these dotted white lines,
those are the exclusive economic zones
of the countries where we tagged these animals.
And the EEZ means that anything that is within that boundary
belongs to that country in terms of resources.
So they can control fishing and mineral extraction,
et cetera, within those dotted lines.
And not a single animal that we tagged left those EEZs,
which was a huge, huge surprise to us.
This was the complete opposite of what we expected to find.
But it's really interesting
because it means that these animals belong
to the countries where we find them
as opposed to being these highly migratory ocean wanderers.
I'm sure some of you are thinking,
you put these tags on for six months
and these animals live for 40 years or more maybe.
So what does that really tell us about
their movements over longer timelines?
And of course, we had the same thought
and we followed this up with a few different methods,
genetics and something called stable isotope analysis
which tell us similar things.
A little more course resolution than the tags,
but over much longer timescales.
And all three of these methods agreed
that basically we're looking at a bunch of different,
small subpopulations of mantas
as opposed to these ocean wanderers.
I don't have my other one.
I usually have the manta flight map that we expected to see
with these animals crossing the Pacific.
And instead what we found were these really,
small isolated subpopulations.
Again, just a huge surprise to us.
So to recap that, we've learned that these animals
are not nearly as migratory as we expected them to be.
They can certainly move around a bit
but they're not leatherback turtles
crossing the Pacific every year.
These small isolated subpopulations are almost definitely,
more vulnerable to human impacts
because we know that they can't really reproduce quickly.
So small isolated populations have fewer animals,
which means that they're more likely to decline
if there are fisheries and other impacts.
And sure enough, we've seen these
dramatic precipitous declines in many places.
This helps explain why that might be happening.
The good news, if you will,
is that countries have direct control
over the management of these manta populations.
Because again, if you are the United States
and you've got some mantas nearby
in your territorial waters,
it looks like for the most part,
they're not gonna be crossing the border somewhere else
where they might get fished.
So if we protect them,
then we know that we're more or less
effectively protecting these populations.
We don't have to worry too much
about international fisheries
impacting our manta populations.
And this was a really, really important point for us
when we were trying to make the case for
local and national level management strategies
in other countries, Southeast Asia, Sri Lanka,
South America, where there are direct manta fisheries.
And the result of that was we were able to make the case
to some of these countries,
hey, these are your mantas.
If you protect them, you don't have to worry about them
swimming off somewhere else and getting killed.
They're valuable in tourism.
We know that they're worth a lot more.
On average, as a tourist draw than in a fishery.
And so a lot of these countries,
they were really receptive to that.
And in Indonesia and Peru, mantas were completely protected
and those were two major fishing nations for oceanic mantas.
And then in Mexico, it also helped support the increase
in size of a flagship marine protected area
to better encompass the total range of mantas there.
So that's been really good news and also just a really
unexpected finding on our part in terms of
we thought they were gonna be these big oceanic wanderers,
and it turns out they're not.
So I'm gonna move on to.
-: [Kelly Quick question.
People are wondering if you're talking about
the oceanic mantas or the reef mantas
when you're talking about these migrations.
-: I'm talking about the oceanic mantas,
but reef mantas actually move around even less than this.
Or similar
maximum migration distance.
We thought that reef mantas would hang out near their house,
their home reefs and oceanic mantas
would be wandering around.
And it looks like they're both actually pretty resident.
Good question.
So the next topic I'm gonna cover
and the reason I'm covering this is
because it's gonna relate back to
the Flower Garden Banks work that we're doing.
Is where do mantas go to feed?
And obviously we can see them when we're diving
or snorkeling or on a boat.
We see them feeding at the surface
because we are also at or near the surface.
But a pattern that we see repeatedly
is that at some of these dive sites or cleaning stations
or manta aggregation sites where we see mantas a lot,
they're there during the day.
And that's what this plot is showing.
These are tagged data from acoustic tags
which just tell us when they're present at a certain site.
We see that they're present during the day,
and then at night they disappear.
And this is a pattern that we see across species.
So reef mantas, oceanic mantas,
some of the devil rays as well if they ever come into reefs.
They disappear at night and there's been this question of
where are they going at night?
And it turns out that we can use those same satellite tags
to investigate that question
because these tags are recording diving data
as well, depth data.
So we can actually see to what depths
these animals are going throughout the day.
And if that changes between day and night.
And one thing that again was really surprising to us,
was that mantas are spending a ton of time in deep water.
So this graph that you're looking at here,
on the Y axis, these are different depth bins
that the tag is recording how much time they spend in that.
So the X axis is the percentage of their day
that they spend in each of these depth bins.
And then we've got it separated out into night and day.
This is just one month, there's a lot of variability.
This changes across regions, et cetera.
But the key thing is just how much time
they spend in these deep waters.
This can be anywhere from about 150 to around 500 feet
deep on this chart in particular.
And a lot more of that time they're spending down
deep at night compared to during the day.
So what are they doing down there?
Our hypothesis was that they were going down to feed
on something called the deep scattering layer.
So the deep scattering layer,
this is a little bit of a oceanography class.
There are a ton of zooplankton and small fishes
that live down deep round about four to 500 meters deep
so 1500 feet or so.
And they hang out down there during the day
because it's still dark even during the day
it's dark down there.
So they can hide from predators.
And at night they migrate up to the surface,
and that's what we can see here on the right.
I don't know if you guys can see my cursor.
But there's this green band
and you can see it moving up towards the surface.
The X axis here is hour of the day.
And so they migrate up at night
to feed close to the surface.
And they're still hiding from these visual predators
because it's dark at night near the surface.
And so this is called the deep scattering layer.
It's been called the largest migration on the planet
because there's just an absolutely astonishing amount
of biomass that is making this migration
a few hundred meters up and down every single day and night.
And over on the left, we're looking at
one of manta and devil rays preferred prey items,
euphausids or krill.
And this is just showing the exact same thing,
on the left during the day they're down deep,
three or 400 meters deep.
And then they migrate up towards the surface at night.
And we've actually been lucky enough to capture
some of this behavior.
This is just very, very lucky.
A colleague of mine was in a submarine
and happened to capture some video of a manta feeding
on this extraordinarily dense aggregation of krill
which is all that noisy,
snowy, grainy stuff.
That's all just krill.
So you can see how thick it is.
And this manta is down around 150 meters or so,
just going to town.
It found this really super dense aggregation of food.
So again, it's gonna do everything it can
to just hang out and maximize
its feeding efficiency down here.
It turns out that some folks have done things.
You can basically take a tissue sample from an animal
and you can take some candidate prey items
that you think it might be eating.
And you can tell how much of those different prey items
make up that animal's diet by figuring out how much of those
different sources are incorporated into its tissues.
And you can learn that using something called
stable isotope analysis.
So it requires a lot of math,
it requires a lot of assumptions.
There's a lot of uncertainty around
some of the values that we have to assume.
But what you're looking at here
is the proportion of the diet that comes
from mesopelagic prey,
which are those vertical migrators.
So that's the yellow box.
And then the proportion of their diet
that comes from surface zooplankton.
And in this case, this is oceanic mantas
but similar things have been shown for all
of the different manta and devil ray species.
And no matter what math we use,
it turns out that these mesopelagic vertical migrators
are really, really important for oceanic manta
and other manta and devil rays diet.
So they're doing a ton of this,
migrating down to meet these guys as they come up
at night and feeding on them in these really dense schools.
So that seems to be a really,
really important part of their diet.
And we've had one instance.
This is from a study that we did with colleagues
in the Philippines where a fishery was catching
a lot of manta and devil rays.
In the Philippines they catch them in gill nets at night.
And when you'd cut them open,
there were four different species of manta and devil rays.
When you cut their stomachs open,
every single one of them was just absolutely
chocked full of krill.
So we know that that's a really, really important diet item.
I just wanna highlight that these mid-water
and deep-water habitats are really, really important
for all of the manta and devil ray species.
And that is gonna lead me into my discussion
of what we are doing at the Flower Garden Banks
and what we think is going on with mantas there.
And I'm just checking my time.
We've got maybe 10 minutes.
So I think I can get through this.
So the Flower Garden Banks are these really,
extraordinary little salt domes that pop out
from the soft, sandy, muddy substrate
in the Northern Gulf of Mexico.
And they've got these really amazing coral habitats
that have grown on top of the salt domes.
And I wanna make the distinction here
between the Flower Garden Banks,
which are these two specific coral reef habitats and banks
versus the Flower Garden Banks National Marine Sanctuary,
which is those plus Stetson Bank,
and is soon to incorporate many more banks
throughout the Northern Gulf of Mexico.
So for now, I'm just talking specifically about
these two Flower Garden Banks
and a little bit about Stetson Bank.
And I wanna highlight Marissa, Emma and Michelle,
who are really the ones that have made all this work happen.
I've just swooped in and talked about mantas
a few times and gotten to do some fun field work with them.
But they're the ones who were going out every week,
every day to the sanctuary,
doing a lot of the data collection.
And they're the reason that a lot of this work
has been possible.
So I just wanted to acknowledge that.
First of all, let's talk about what species of manta
is at Flower Garden Banks.
So we see these two different types.
And there's again, I mentioned there's so much variability
in those Atlantic and or Caribbean mantas
that it can make it really hard to tell
what species you're looking at.
So we know for sure that those Caribbean or Atlantic mantas
are visiting and using the Flower Garden Banks quite a bit.
But we also think there might be the occasional
oceanic manta coming through.
Hard for us to know with certainty.
And then this one intermediate guy that I think
you'll remember from the genetic discussion I had
at the very start of the talk,
this sample actually came from Flower Garden Banks.
And genetically it's halfway between oceanic mantas
and these Caribbean mantas.
So we're pretty sure that it's actually
a hybrid between the two species.
So they may be hybridizing quite frequently
in the Gulf of Mexico.
We might be seeing hybrids somewhat frequently
at Flower Garden Banks, we really just don't know.
So we know for sure that we've got these Caribbean mantas,
we know we've got some hybrids.
we think we've got some oceanic mantas.
But I hope that illustrates why it's so hard
to pin down what species we're looking at
because they might even be producing these hybrids.
So that just made it more confusing probably.
But we definitely have the Caribbean mantas.
When we think about why mantas come to reefs
and to aggregation sites, often one of the reasons
is that they're coming to clean.
So they spend a lot of time in open water and deep water.
They pick up big parasite loads and they have to come
to reefs so that these cleaner fish
can pick those parasites off of them.
And so we're looking at that right here.
These are Clarion angelfish
cleaning an oceanic manta in Mexico.
So this is on the Pacific coast of Mexico.
Another reason that they might come
to some of these sites is to feed.
So places in the Maldives for example,
in Australia, they'll come to these reef habitats
because they're aggregators of plankton.
They can create localized upwellings,
so they might be good feeding opportunities.
But weirdly at Flower Garden Banks,
we don't really see either of those things happening.
There are a couple of historical records
by Emma and by some other folks who work
or who have visited the Flower Garden Banks
of mantas feeding there.
But really it's not a common observation,
it's not a common occurrence.
And we don't really ever see them cleaning.
So they're not stopping at the cleaning stations
that we know do exist at Flower Garden Banks.
They just pass by those.
So this has been a question of why are these mantas
coming to Flower Garden Banks?
One of the first things that I noticed the first time
that I got in the water with a manta at Flower Garden Banks
was how extraordinarily tiny it was.
It was probably the smallest manta
I'd ever been in the water with.
And when we started looking through the photo ID catalog,
we noticed that pretty much every manta that we could tell
that it was a male, was a juvenile male.
And the way that we can tell that,
is that male sharks and rays have these things
called claspers, which are their sex organs,
which pop out of their pelvic fins.
And when they've got these tiny little claspers
that means that they're a juvenile,
they could even be a newborn.
And it's not till sexual maturity in mantas
that these claspers extend beyond the fins.
And you might even have trouble
seeing these claspers here.
If you're not looking for them,
you might think that this is actually a little female.
But they have these two tiny, tiny, little claspers.
So we can say that this is a juvenile male.
And it turned out that when we started looking
in depth at these little tiny mantas,
93% of the mantas in that photo ID database
that we could tell were males were immature,
which is extraordinary because we very, very rarely see
these small mantas anywhere in the world.
So this is the distribution of sizes of mantas
from the Flower Garden Banks.
You'll see that they're really small
and most of them are less than three meters.
I've also put on here for reference,
these vertical lines are the size of maturity
for oceanic mantas and for reef mantas.
These are Caribbean mantas,
we don't really know what the size of maturity is.
But if it's something close to oceanic or reef mantas,
then pretty much all of these animals
are likely to be immature juveniles.
And when you look at any other population of mantas
around the world, normally you see that that sort of less
than three meter range is completely absent.
We rarely see mantas that are that small
in other populations.
And it turns out that that is pretty much
the exact distribution of sizes of mantas
at Flower Garden Banks.
So instantly we thought,
hey, this might be a nursery habitat for mantas.
This had been small mantas had been seen before.
And it had been proposed that,
hey, maybe this is a nursery habitat at Flower Garden Banks.
It turns out that just seeing small mantas
or juvenile mantas isn't enough to call something
a nursery habitat.
There are three really specific criteria
for establishing a shark or ray nursery area
or for defining or classifying
a shark and ray nursery area.
Which there have to be more juveniles
at that site than other places.
They have to remain in that area for extended periods.
And they have to use that site repeatedly across years,
so it can't just be like,
oh, hey, one year there were a bunch
of little baby sharks or rays over here
and then we never saw that again
but let's call it a nursery.
That doesn't fly.
So it turns out that Flower Garden Banks
actually meets all of these criteria.
So we were able to classify it as a nursery habitat.
Again, this is just the banks themselves
not the entire marine sanctuary.
But it's curious because some of the other places
that have since then been defined as well as
either reef or Atlantic manta nurseries have really
different characteristics than the Flower Garden Banks.
They tend to be these coastal,
sandy, sheltered,
warm areas where a little baby manta
can grow and be safe from predators.
They're typically these like shallow coastal areas.
And that also fits with what we know
about shark and ray nurseries in general.
These are typically places where sharks and rays
can hide from predators and get food
until they grow big enough to be safe
in the wider ocean essentially.
So what the heck is going on at Flower Garden Banks?
It doesn't seem like it really fits that pattern.
I'm using this map now.
This is
the expanded sanctuary,
the proposed expanded sanctuary boundaries just to show you
where the sanctuary is in context.
So it's in the Northern Gulf of Mexico,
but it's right on the edge of the continental shelf,
just really right dangling over the side.
So the water there is relatively shallow,
but it's adjacent to this continental slope
that gets down to really, really deep water
really, really quickly.
So just remember, in the Northern Gulf of Mexico
we also see these deep scattering layers
that I was mentioning before,
these really super productive mid-water habitats
with tons and tons of zooplankton
and small fishes that are gonna migrate close
to the surface every night.
So we think that that proximity to deep water
might be important for feeding opportunities.
One thing I haven't mentioned yet is that
after devil rays and manta rays spend a lot of time
down in these deep cold waters feeding,
they have to recover that body heat.
They're cold blooded animals.
So they often come up to the surface
and they just hang out right at the surface,
soaking up the sun's rays.
And this is somewhere that lots of people see mantas
just basking at the surface.
Of course, if you're a big flat object at the surface,
you've got a big silhouette.
And if there are sharks and predators underneath you,
you're kind of a sitting duck.
And we do know that in that Northern Gulf of Mexico area
and specifically at the Flower Garden Banks,
there are a lot of big predators, big sharks in particular
which happened to be one
of the primary predators for mantas.
And this is just one tiny little manta
that I was lucky enough to see a few years ago.
And you can see he's got big chunks taken out of him
by very clearly a shark got ahold of him
but he managed to get free.
So we know that there are predators around,
we know that these guys are vulnerable
when they're so small to predation by sharks.
And so to put all these concepts together
and explain what I think is going on
at the Flower Garden Banks.
My hypothesis or my guess is that both the adult
and juvenile mantas are probably feeding
on these deep, really dense schools of krill
and euphausids and vertical migrators.
When they come up a little bit closer
to the surface at night, we think that the juveniles
and the adults are going down to feed on them.
And then when they need to recover their body heat,
I think that the adults probably are just
going up to the surface.
They're big, they don't have to worry about
predators as much.
But I think that the juveniles probably still have
to find some kind of safe harbor.
So they might be coming up to the Flower Garden Banks
where they can cruise around close to the bottom,
avoid predators, warm up in those warm near surface waters
without exposing themselves
to that additional predation risk.
So that's purely a hypothesis,
it's putting together everything that we know about mantas
in other regions and trying to come up with an explanation
for the patterns that we are seeing at Flower Garden Banks.
We've started doing some really,
initial satellite tagging there.
We're really interested in where these animals are going.
It's a rare opportunity for us
to directly study the juveniles.
We don't have access to juveniles, very many places.
So we're really interested to see if they're doing something
different from the adults.
So far, we've only managed to put one tag out,
this is from 2019.
We were hoping that this past summer
we'd be out there tagging mantas.
But of course, that didn't go to plan with COVID.
So from this really preliminary data,
we can say so far that it seems to be matching the pattern
that we are expecting to find.
Where they're spending a lot more time deeper at night,
they're going down to these depths where we might expect
to see the deep scattering layer
coming up close to the surface.
And then during the day, they're coming up
into shallower areas.
We also know that they're moving between banks.
So the tagged animal, the tag popped off
close to Bright Bank which is gonna be one
of the additional banks included
in the expanded sanctuary boundaries.
So we're really interested as we tag more animals
to see how they're using these other nearby banks,
how they're using this larger shelf habitat
that's right on the shelf break.
That's gonna be really, really interesting for us.
So stay tuned for that.
So takeaways from Flower Garden Banks.
Pretty much all of the mantas that we see
at Flower Garden Banks are juveniles.
And that is really extraordinary
because we don't see that in many other places,
there are a few known nursery habitats.
So we were able to formally classify
the Flower Garden Banks as a nursery habitat.
It met all of the criteria that we need
to use in order to actually call something
an official nursery habitat.
We don't yet know how they're using these other banks.
If they serve as a similar function
as the Flower Garden Banks.
We're really, really excited to learn more about that.
We think the reason these banks are important
is because they're close to these deep waters
that probably have lots of
foraging opportunities for the mantas.
But they also provide some protection afterwards,
where they can come back, heat up in these warm,
shallow waters without exposing them to
as much predation risk.
And we're also really interested to see
if these juveniles are moving around.
Maybe they're moving more than the adults.
How are they moving throughout the Gulf of Mexico,
the Atlantic, the Caribbean?
So as we tag more animals, we'll get to hopefully
answer some of these questions.
I'm certain I've gone way over my time.
I have a special shout out to all the great folks
at Flower Garden Banks who have helped
to make this work happen.
Funding from National Marine Sanctuary Foundation.
I got started on this project thanks to
the fellowship I had through the Nancy Foster Scholarship
through National Marine Sanctuaries.
And then some collaborators at
the Southeast Fisheries Science Center
as well who are helping with this work.
And then I'm just gonna skip through.
All this work is super collaborative,
loads of international collaborators.
So thanks to all of them for contributing
and all the funders and supporters.
And I don't even know, do we have time for questions?
Sorry about that.
Kelly: So we have reached our hour limit
and what I will do now is do our usual wrap up.
But just to let you know,
if you'd like to hear some questions answered,
Josh has agreed to stay on about another 10 to 15 minutes.
I understand that most of you have probably planned
on being here for an hour.
So like I said, we will do our regular wrap up
and then we will jump over and have Josh continue
to answer questions for another 10 to 15 minutes.
So if you'd like to stay with us, we invite you to do that.
You're more than welcome.
And we will get to your questions momentarily.
In this case, I'd like to say that
we do just have that 10 to 15 minutes after the fact.
So if you have questions, we've gotten many questions
already lined up for you, Josh.
So that should not be a problem.
But we are going to take those from the question box
and we will read them out to him
and we will cluster them.
A lot of you have similar questions.
So if we don't answer yours specifically,
we'll probably get one answer that's very similar.
Let me go back to sharing my screen real quick
so we can wrap up what we've got going here.
And make sure you're seeing what I think you are.
So depending on the number of questions,
we will take that extra 10 to 15 minutes.
As a reminder to those of you who are educators,
we have provided a Manta Mysteries activity
in the handouts pane of the control panel.
I understand that some of you had some difficulties with it,
you just have to double click on it to download it.
If you still have difficulties,
please go to our website at flowergarden.noaa.gov.
It's also in the chat box for you.
We have a For Teacher section there
and you can find the manta mysteries activity
in that teacher's page.
Thank you for attending our Seaside Chats presentation
on Manta Rays, The Mysterious Giants in Our Backyard.
This is the second in a series of four presentations
we are offering this month.
We invite you to register for the remaining chats
by visiting us on the web at flowergarden.noaa.gov.
And we promise that our other topics will be just
as engaging and informative.
Next week, we'll be talking about Weathering Storms
and what happens on land during storms,
as well as what happens in the ocean
is affecting our coral reefs and the Flower Garden Banks
and the rest of the Gulf of Mexico.
And then the following week,
we're gonna talk about Remarkable Algae
because this has proven to be a really fascinating subject
with the deep areas that are part of
the existing sanctuary as well as all
the new expansion areas, and the neat algae habitats
that have provided so much background knowledge for us
now and the more we explore.
So we'll have a researcher talking to us about that.
Today's presentation has also been part of
the National Marine Sanctuaries Webinar Series
and while Seaside Chats last just one month,
our National Webinar Series continues throughout the year
to provide educators with educational
and scientific expertise, resources and training
to support ocean and climate literacy in the classroom.
Be sure to check the website for recordings of past Webinars
and a schedule of what's to come.
As a reminder, we will share the recording
of this Webinar via the National Marine Sanctuaries
and Flower Garden Banks National Marine Sanctuary websites.
And if you know people who didn't make it tonight
who wanted to, if they can still use the link
for getting into the Webinar tonight to access
the recording live on the Webinar site.
If they'd like to do that tomorrow.
Following this webinar, all attendees will receive
a PDF copy of a certificate of attendance that provides
documentation for one hour of professional development
for today's presentation.
This includes our Texas CPE provider number
for those of you who are Texas educators.
And if you are an educator outside of Texas,
please use this certificate to help
get your hours approved in your district.
If you require additional information,
please contact me at flowergarden@noaa.gov
and I'll do what I can to help you out with that.
There will also be a short evaluation that asks questions
for you to answer following today's presentation.
Please complete the survey immediately
after signing off the Webinar.
It should only take about three minutes to complete
and we greatly appreciate any feedback
you are willing to share.
Thanks again to Josh for a great presentation
about manta rays and their relevance to
Flower Garden Banks National Marine Sanctuary
and the Gulf of Mexico,
as well as their their status worldwide.
And thanks to all of you for taking the time to join us.
This concludes the main portion of our Webinar.
Anyone who would like to stay on,
we will start sharing questions with Joshua.
Josh, you ready?
-: I'm ready.
Get me talking about mantas and I just can't stop.
(Kelly laughs)
-: So there've been several questions about the manta tags.
What are they made of?
How do you find them after they pop off?
How do you collect them?
Kind of the general logistics about the tags you use.
-: Sure.
So what are they made of?
Good question.
I don't know.
I think they're resin coating.
They're super robust.
They can go to like 2000 meters depth before they implode,
so over a mile deep.
And we put them on the animal with a pole spear,
as a little anchor or a dart on it that goes
under their skin and then holds it on.
And as I said, there's not much of a reaction
to that tagging process.
They stay attached for as long as we tell them to
or if they pull out early, that's also a thing
that happens sometimes.
And then we don't actually have to collect them,
they float to the surface and they send all their data back
via satellite which is really cool,
because they pop off in the weirdest, wildest places,
way off shore.
And there's no way we'd be able to get them back.
Sometimes they wash up on a beach.
I had one that I deployed in Mexico
float across the entire Pacific after it popped off.
And a Navy ordinance disposal technician
found it in Guam and sent it back to us.
And when that happens,
you can pull a bunch more data off of it.
It has much finer resolution that it can't transmit
all of that by satellite. So that can be handy.
So hopefully that answers most of those questions.
Kelly: Great.
What do you think about the manta night dives in Hawaii
where they use lights to attract mantas?
And along with that and how about
the issue of touching mantas?
How are these things affecting the mantas behavior?
-: There's been a lot of increasingly some more work looking
at how diver interactions can influence mantas.
Overall, tourism is a really positive thing.
Ecotourism provides livelihoods for folks in areas
where they might otherwise turn to fishing let's say.
It's good for anybody to be able to demonstrate
the economic value of mantas.
And so in general, we think that tourism
is a really good thing.
It doesn't mean that unrestricted tourism
will always be good.
There are lots of records and now some more formalized
studies coming out showing that diver behavior
can influence manta behavior.
If divers are chasing mantas, they'll quit feeding,
they'll quit cleaning, they'll leave the reef, et cetera.
Humans can definitely be disruptive
even when they're just tourists, divers.
So it's really important that,
and more and more tourism operators are recognizing that
they have to follow best practices.
They have to educate divers and snorkelers
before they just toss them in the water with mantas,
so they know what not to do.
And also maintaining limits so that you don't have
1,000 people trying to chase after one manta
for that perfect manta experience or whatever.
With that in mind, the night dives in Hawaii
are really super cool.
I think a lot of operators do a good job of educating people
so they know not to touch the mantas,
not to chase the mantas, just to kind of stay put
and watch it happen around them.
And when they follow those rules, I think it's really great.
I'm supportive of that.
Kelly: The next batch of questions has to do with
mating behavior and the number of pups over a lifetime.
And do they care for the pups?
-: So mating behavior, I didn't really go into that at all.
Or else you would have been here for another two hours.
Kelly: All right, a condensed version.
-: Courtship behavior is really cool.
We don't know that much about it.
We know that they kind of court
and have these mate pre-mating behaviors
at reefs and at cleaning stations.
So we rarely see in the oceanic mantas mating behavior,
we see a little bit of it in reef mantas.
It happens at these socializing sites
where they come to aggregate.
How many pups do they have over their entire life?
It depends probably on the animal,
and the location, and how productive,
how many resources there are for them there.
But we know that there are gaps between two to seven years.
So if they take 10 years to reach maturity
and then they live for another 40 years
and have a pup every five years,
that might be five or 10 pups in their entire lifetime.
Very few.
And as far as we know, once the baby is born
there is no parental care at all.
There's no nursing or anything
but there's also no protection.
The pup is just on its own.
And that's probably why they come out so big.
So other animals like other sharks that have larger litters
of five or 10 or 20 pups,
they devote less resources to each animal.
So each one probably has a lower chance of survival
but there are more of them.
Whereas mantas are devoting a huge amount of resources
to growing a really big single pup who's probably
more likely to survive because it's so big.
But there's no maternal care or anything after it's born.
Kelly: Next question is micro plastics
and how they might be affecting mantas.
-: A big concern.
Lots of folks are interested in that question.
The one thing that I will say.
First of all we don't know.
People are looking at that.
Obviously they're filter feeders.
It would be hard for them to discriminate
between a plastic and a zooplankton
if they're just going through feeding.
Although it does seem like they can be selective.
So maybe if they went through an area with a ton of plastic,
maybe they'd stop feeding.
The one good thing I'll say is that most micro plastics,
not all, but most seem to float.
And it accumulate close to the surface.
And as we've seen mantas and devil rays spend a lot
of time feeding down deep,
where as far as I know micro plastic,
is not that they're not there,
but they're just lower concentrations.
So it might be less of a risk than if they were feeding
closer to the surface.
But big unknown for us.
Kelly: And any information on how the Gulf oil spill
affected the mantas?
-: We don't really know.
That happened before we were
focused on any of these tagging efforts, what have you.
As far as I know, I haven't specifically looked at this,
but I don't think that there was like a dip in sightings
at the Flower Garden Banks, for example, around those years.
Hard to say.
I can't give a really good answer but nothing specific
that I know of in that case.
Kelly: And I think in the interest of time
we will make this the last one.
The question surrounds all the hybridization discussion
and the differentiation between the three species.
Is the disconnect.
It is the third species because of DNA?
Is it because of the lumping versus scattering preferences
of the primary investigators?
Is the hybridization?
Maybe the third group is all hybrids?
A whole cluster of questions along those lines.
-: It's funky. That's for sure.
First let me say that species is a human definition.
And now we're getting a little philosophical.
But nature isn't working in defined species.
Nature doesn't say like,
okay, I've had a new species, so call it this.
These processes evolve over time
and we're assuming that we're looking at them
at a snapshot where everything is able to fit neatly
in it's nice little box.
In reality, these things could be in process.
So it could be that,
the sort of the divergence
of these two species is in the mix.
And if we give it another few million years
maybe then it would be a lot more easy to identify them
and to differentiate them genetically.
And maybe we wouldn't see hybrids.
But we might not be at that stage
where they're fully diverged.
It might be an ongoing thing.
So that's the first thing I'll say is that these
are human derived labels of what species are.
That being said, there are very, very clear
genetic differences in most of the ones that we sample,
between the Atlantic mantas and what we think of
as the oceanic mantas.
So we know that there are genetic distinctions
and finding hybrids is not so uncommon.
That's something that there have even been some oceanic
and reef manta hybrids identified.
So we haven't done enough work to really know exactly
what that means in terms of speciation,
it definitely complicates things.
But the tricky part is that we know genetically speaking
that there's a third species,
but it's really hard to find these morphological
characteristics that are consistent between
the Atlantic and the oceanic mantas.
And that just makes it inconvenient for us
to be able to put things in a box.
And it's not uncommon to find really similar things.
They're two hammerhead shark species that both occur
on the East Coast of the US.
And visually it's almost impossible to tell the difference.
You have to I think count how many vertebrae it has,
to be able to say which is which.
But genetically you can tell the difference.
And visually you can.
Me now having looked at hundreds of photos of Atlantic
and oceanic mantas and been in the water with them,
I can look at one and say,
that's almost definitely an Atlantic manta
or, hey, there's a really good chance
that's an oceanic manta.
It's not like a hard line.
It's a bunch of different characteristics that all
weigh in on that identification process.
But I think we can very confidently now say
that there is a lot of evidence including
really robust genetic data that indicates
there's a separate species.
So we're just waiting for it to be formally described.
Hope that makes sense.
Kelly: Thank you, Josh.
Thanks again for the great presentation.
Thanks for agreeing to stay on another 10, 15 minutes
for us to get some questions answered.
There are still many in the wings.
And so folks, if we did not get to your question,
we will see what we can do as the sanctuary staff
to answer some of those questions for you.
And maybe we'll pass a few on to Josh
to see if he can help us out.
And if we can get answers to some of those questions for you
we'll share those with you via email after the fact.
So give us a couple of weeks and we'll see what we can do
about answering some more questions.
Thanks again, Josh.
Appreciate all your extra time and your expertise
and your willingness to be part of
our Seaside Chat Series.
Thanks to all of you for taking the time to join us.
And this concludes today's Webinar.
Thank you.