Ocean Giants #06 | WINTER 2022 | OCEAN GUARDIANS | MANTAS | WHALE SHARK MYSTERIES | ECOTOURISM

MMF collaborator, Stella Diamant, wearing Waterlust’s Whale Shark Warrior Leggings. Madagascar

ON FACEBOOK & INSTAGRAM

TO HELP THEM GROW

The Munich fashion start-up "Mantahari Oceancare" was founded in 2018 as a non-profit organization by Tim Noack. During his time as a diving guide in Komodo/Indonesia, one topic touched him above all: the pollution of the oceans by plastic waste. Thus a good portion of their profits is donated to MMF’s marine conservation projects in Indonesia. These projects focus on the protection of manta rays and other marine life and public education, scientific capacity building and government engagement through research and science to enable long-term environmental protection.

The startup's product range includes apparel made from recycled PET bottles.

To closely engage with the projects on the ground Mantahari regularly adopts individual manta rays (over 150 and counting) and has contributed > USD 30K in project funding.

SAVING OCEAN GIANTS FROM EXTINCTION.

COVER

Manta ray in Komodo.

Our mission is to save threatened marine life using pioneering research, education, and sustainable conservation solutions. Our objective is a world where marine life and humans thrive together.

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CREATIVE EDITOR & DESIGN

Madeleine Pierce

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Photo by Jerry Arriaga

Dr. Simon J Pierce

WELCOME BACK TO OCEAN GIANTS!

For this winter issue, I’ve interviewed Elitza Germanov about the manta rays of Komodo National Park in Indonesia, Genaye Domenico introduces the Ocean Ambassadors program in Mozambique, and I roped Clare Prebble into sending through an article on her first time whale-sharking in Mexico. I’ve also summarized my favorite whale shark mysteries – for a bus-sized fish, they sure are good at avoiding us.

One lovely piece of news we’re able to share is Andrea Marshall being inducted into the ‘Women Divers Hall of Fame’. I’ve been lucky enough to know Andrea since 2002, when we were both starting our postgraduate studies in Australia. Once I realized the loud American was actually pretty cool, when you got past the melodrama, we quickly became great friends. I encouraged her to study wobbegong sharks for her doctoral studies. I’m glad that didn’t work out, as shortly after she invited me over to Africa to help with her actual PhD work, on the manta rays of Mozambique, and to take a look at all these whale sharks she was driving past. And, thusly, MMF was born.

That Andrea has gone on to make so many discoveries on manta rays and other species is no accident; it isn’t luck. She’s an incredible observer, and a fantastic diver, albeit an atrocious buddy. I soon learned that ‘helping her’ underwater meant ‘kick frantically to keep up’, until I flat-out

stopped caring and just reverted to waiting at my favorite manta cleaning station on the reef. She’d be sure to come back eventually, to check for mantas. Meantime, her squeaky regulator meant I always knew she was alive, somewhere off in the distance…

Andrea’s done it tough – she had to sell all her stuff to self-fund her initial work in Mozambique, then her house burnt down, our office got stripped clean by thieves, she’s had a bunch of weird parasites, and spiders exist. Through all the arachnophobia, and having to make fires with coconut shells to heat water for a shower, she’s kept on being an incredible field scientist. For hours after each dive, she’d take copious notes, sketching the mantas, and dreaming up novel ways to track their behaviors. All this work has compounded into unprecedented insights on these wonderful species.

Without Andrea’s sheer stubborn determination to change the world for the better, MMF wouldn’t exist – and we wouldn’t have all this cool stuff to share with you all. So congratulations Andrea on this prestigious award; you’ve absolutely earned it.

DR. SIMON PIERCE

Co-founder, Principal Scientist

Andrea & Simon when they were little science babies.

UPDATES

Dr. Andrea Marshall was inducted into the Women Divers Hall of Fame.

MMF’s manta team prepared a global research update for World Manta Day.

WHALE SHARK mysteries

PIERCE

Until the 1980s, there had only been a few hundred reported encounters with the species. Even Jacques Cousteau only ever saw two.

(previous) A satellite-tagged whale shark in the Galapagos Islands.

Whale shark aggregation off Qatar.

WRITING A TEXTBOOK ON WHALE SHARKS

gave me plenty of time to reflect on all that we know – and don’t know – about the world’s largest fish. I thought it’d be fun to share some of the mysteries that still remain!

Cousteau only ever saw two. We know now that the key is finding places with high densities of their preferred prey, zooplankton and small fishes. Whale sharks have permanent munchies. In some areas, like off the Yucatan coast of Mexico, several hundred sharks can be seen feeding at once, gathering in sharky constellations to exploit mass tuna spawning behavior.

That’s interesting in itself, but not particularly mysterious. The odd thing is that it’s almost exclusively male whale sharks that frequent these areas. It’s almost a cliché now that the sites associated with whale shark tourism – think Ningaloo Reef in Australia, South Ari in the Maldives, Mafia Island in Tanzania, and others as well – are dominated by juvenile male whale sharks. The occasional juvenile female is certainly present, but it’s rare to see adult 9–10 m females at any of these locations.

Whale sharks are awesome. They grow from 50 cm at birth to become the largest fish that has ever lived. They dive to at least 1900 m. They swim over 10,000 km a year, often without approaching a coast. And they manage all this with a big goofy grin and a general ‘oceanic Labrador’ vibe. These gigantic spotted himbos really are quite endearing. I fell in love with whale sharks the first time I got to work with them, way back in 2005. At that stage, little was known about their lives and habits. We’ve learned a lot more in the years since (cue sound of our 340-page textbook thumping on the table), but some interesting mysteries still remain. Journey with me, gentle reader, as we travel into these uncharted waters…

WE’VE ONLY FOUND PART OF THE POPULATION

Whale sharks were only discovered by Western scientists in 1828. Until the 1980s, there had only been a few hundred reported encounters with the species. Even Jacques

‘Sexual segregation’, as this situation is referred to, is common in sharks and rays. Normally, though, the ‘segregated’ part of the population hasn’t proven hard to find. In whale sharks, for the most part, we still don’t know where the females live. They seem to be using completely different areas.

Why aren’t female whale sharks taking advantage of these predictable buffets? Well, adult and subadult male sharks will both harass juvenile females (also each other, boats, whale shark researchers, etc.), so that’s one possible reason for the females to avoid them, but this segregation persists even in places where no large males are present.

Perhaps productive feeding areas attract more whale shark predators? For males, the main aim is just to eat lots and grow fast to reproductive size; rich, but risky, habitats might be worth it. Females benefit (in evolutionary terms) by playing the long game – growing slower to a larger size – so they may prefer to live in safer areas elsewhere. Smart.

I think it’s most likely that females are feeding on slightly different prey, and presumably offshore; otherwise, we’d be seeing them more often. The best way to answer this conundrum will likely be through long-term tracking studies that allow us to compare and contrast habitat preferences between the sexes directly. We can also use biochemical techniques to look at long-term diet and habitat use across populations. Early work using these methods hasn’t seen many clear differences emerge between the sexes yet, but... most of our data is from males, because we know where they are. Le sigh.

WHERE ARE THE PREGNANT WHALE SHARKS?

The few exceptions to the ‘rule’ outlined above are now key study sites for the species. Whale sharks are a globally endangered species, and large juvenile and adult female sharks are the most important individuals for population recovery (i.e., they can produce more whale sharks). It’s frustrating that we know so little about them. The northern Galapagos Islands is one area where adult female sharks are regularly seen, and it’s one of my favorite places to work. Most of the sharks we see there are 10–12 m in length, and almost all are females. It’s not a feeding area, and they don’t stick around – most sharks are only there for a day or so at most. When I first saw these sharks, apart from being gobsmacked by their sheer size, I was flabbergasted by the junk in their trunk. These sharks had a massive ‘bump’. They were clearly pregnant.

Close approach by a friendly juvenile manta ray.

(above) Dr. Rui Matsumoto ultrasounding an female whale shark.

Finally, in 2018, we were able to recruit the Okinawa Churaumi Aquarium research team to join us for an expedition. These Japanese scientists are the world leaders in using waterproofed ultrasound units for reproductive assessments. They collected ultrasounds from multiple sharks, and… no babies. Whale sharks have extremely thick skin, so it’s difficult to be definitive about it, but it seems likely now that females close to adulthood develop a pronounced butt – but it doesn’t necessarily mean they’re carrying pups. Confusing, but that’s why they say never to work with animals.

For the moment, anyway, we’re back to having only one confirmed pregnant whale shark to talk about. That 10.6 m ‘megamamma’, caught off Taiwan in 1995, contained around 300 cute little bonsai pups. It’s very rare to see adult female whale sharks close to the coast, so we assume they’re living in the open ocean. That makes them hard to study. There aren’t many places where we can intercept them, so offshore islands and seamounts are going to become increasingly important whale shark research sites.

WHERE ARE THE BABIES?

If bus-sized pregnant sharks have proven challenging for us to find, imagine trying to find a 40–60 cm baby. Only 30–40 newborn whale shark pups have *ever* been found, scattered across the world. Pups are born free-swimming, and likely get no further assistance from their mother.

My working hypothesis (= arm-waving speculation) is that we don’t see them because the mothers are giving birth well offshore, away from coastal predators, and the babies are following the daily vertical migration of plankton from the depths to the surface when darkness falls. I could be embarrassingly wrong though. It wouldn’t be the first time.

EXPLORING THE ABYSS

Whale sharks are incredible deep-divers – probably to over 2000 meters (whereupon the pressure crushes our tags). The open ocean may be boring at the surface, but there’s plenty going on in the mesopelagic depths just a few hundred meters beneath. Literally trillions of lanternfishes, probably the most abundant vertebrate on the planet, live in this twilight zone. They’d make an excellent snack for a hungry whale shark. But why keep going deeper?

Well, there are lots of good reasons not to go deeper. There isn’t much food in the deep ocean, it’s lower in oxygen, and it’s very cold, with whale sharks occasionally facing nearfreezing 2ºC temperatures. They aren’t just diving for the fun of it, as they have to spend time warming up at the surface afterward. We’re not sure what the purpose of these deep dives is yet, but an intriguing possibility is that it’s a part of the shark’s geomagnetic navigation strategy – they can likely get a better fix on the Earth’s magnetic field closer to the crust, much as we might go outside to get a better GPS signal.

At the moment, whale sharks are showing us the limits of our technology depressingly, and expensively quickly, so the reasons behind these behaviors remain unknown.

HOW OLD DO WHALE SHARKS GET?

Whale sharks become adults at about 7–9 m length in males, and about 9–10 m in females. Age-wise, our best guess is that those sizes correspond with about 25 yrs for males, and 30–40 yrs in female whale sharks. We know that the largest whale sharks ever recorded have been in the 18–20 m range. Working out their maximum lifespan should therefore be a simple exercise in extrapolation then, right?

Only 30–40 newborn whale shark pups have *ever* been found, scattered across the world.

Adult female whale shark showing off her pronounced ‘butt’. (below) The structure of a hypothetical whale shark population.

Whale shark aggregation at St Helena Island.

If only it were that easy. Shark skeletons are made of cartilage, not bone. The ‘centra’ in their vertebral column continually grow as cartilage accretes through time. Like a tree, the centra forms a dark (dense) band during times of slow growth, and a lighter band when the shark grows faster. Each band pair can represent a year, as in trees. Unfortunately, whale sharks – and you can trust me on this, I’m a doctor – are not trees. They swim, a lot. Whale sharks feel no obligation to suffer through winter. If it gets cold, they just... go somewhere else. That means the band formation may not be annual.

But wait, there’s more. Once they get to around their adult size, whale shark growth slows dramatically, so the relationship between the shark’s size and age breaks down completely. Two whale sharks, Stumpy and Zorro, have been returning to Ningaloo Reef in Australia for over 20 years now. The research paper describing their sighting histories notes that “their growth has been negligible over the past two decades.” They may still form bands in the centra, but there’s a good chance they’ll be indivisible even under a microscope.

So how old do whale sharks get? We don’t know. Most large shark species are long-lived and slow-growing. Greenland sharks, living in the cool Arctic and deep waters, grow less than 1 cm per year and can be over 6 m at full size.

A 5 m female was estimated to be 392 years old. Female white sharks only become adults at about 33 years and are estimated to live to at least 73. Even small spiny dogfish are thought to live for at least 80 years. There’s a good chance that the whale sharks’ maximum lifespan will easily exceed our own.

EMBRACING THE UNKNOWN

Whale sharks are a genuinely special species. They’re gigantic. They’re iconic. They’re also globally endangered. Their large size, placid nature, and the existential threat to their very survival keeps motivating us to develop new and improved research techniques to learn more about them, and how best to protect them.

Many of the non-invasive study techniques that were first pioneered on whale sharks, like photo-identification, are now standard methods in shark research, and we’re pushing forward to integrate artificial intelligence with image processing so we can work faster. Some of the first satellitelinked tags were designed for and deployed on whale sharks to track their movements across vast distances. Whale shark scientists are continuing to trial new techniques like ultrasound on free-swimming sharks, as above, underwater blood draws, even in-water semen collection which… yeah. That may have been a one-off. (No judgment, though. For science!)

We’ll keep solving mysteries – but that certainly doesn’t make their lives any less interesting. Colossal as these sharks may be, their very existence embiggens us all.

(left) A (much younger) Simon preparing a stranded whale shark’s vertebral centra for X-ray.

THE WHALE SHARK BOOK

WHALE SHARKS, THE LARGEST

FISH THAT HAVE EVER LIVED,

have long captured the interest of scientists and the imagination of the public. The first scientific textbook on the species, co-authored by MMF’s Dr. Simon Pierce, brings together the world’s leading experts on whale sharks to uncover the lives of these awesome ocean wanderers.

OCEAN AMBASSADORS

AMBASSADORS

HEALTHY OCEANS AND HEALTHY PEOPLE

ARE INEXTRICABLY LINKED. For the people of Mozambique, fishing is steeped in history, and provides the country with 40% of its dietary animal protein. Sadly, fishers have been reporting steep declines in the size and quantity of their catch, making traditional fishing methods and management strategies difficult to sustain.

The pressures of a growing population and overexploitation by foreign fishing fleets have led to fishers switching to indiscriminate techniques to maintain catch rates. That, in turn, has led to more accidental catches of threatened species. As preferred fish have declined, some previously-ignored endangered species have also become increasingly attractive as a target for fishers. The results have been devastating.

MARINE MEGAFAUNA DECLINES

Since 2005, the MMF research team has documented a 98% decline in sightings of reef manta rays, and 79% in whale sharks. We have seen first-hand the impact that unsustainable fishing practices can have – not just on the rays and sharks that we spend much of our time on, but on bass, sea turtles, dugongs, and dolphins too.

Our focus now is on helping these species to recover. To achieve that, we need to solve the root issues that led to their declines in the first place. That means we need to help fishers transition back to sustainable methods that still ensure food security in their communities.

The goal of MMF’s Sustainable Seas Program is to ensure that people can benefit from a healthy ecosystem that supports livelihoods and food security, while threatened and vulnerable marine species are protected so their populations can rebuild.

For the people of Mozambique, fishing is steeped in history, and provides the country with 40% of its dietary animal protein.

THE SUSTAINABLE SEAS PROGRAM

Our flagship conservation project in Mozambique is the “Ocean Ambassadors” program. The MMF conservation team members work with community ambassadors to build their knowledge and technical capacity on sustainable marine resource management. The program started with 12 ambassadors in 2017, and we now have 38 people with whom we work together to continually develop a conservation curriculum that, at this stage, comprises 16 lessons encompassing topics on marine conservation, species protection, and ecology.

After we meet with the ambassadors, they in turn organize a monthly meeting to share and discuss their knowledge within their communities. Over 2,400 people have now attended these meetings. The ambassadors also work with MMF to develop and participate in ocean festivals, beach cleanups, and other environmental initiatives.

EMPOWERING LOCAL MANAGEMENT

We also work directly with the fishers themselves. Mozambican law enables the development of Community Fisheries Councils as local consultative bodies for the provincial and national governments. To help formalize their management authority, the MMF team is helping fishing communities with the process of legal registration, hosting exchange visits with other fishing communities to share their knowledge, facilitate planning for Locally Managed Marine Areas, and finding training and apprenticeship opportunities for fishers and their family members who wish to explore alternative or supplementary livelihood opportunities.

Empowering community leadership in conservation is the most effective way for us to ensure long-term improvements in fisheries management. By providing practical help to the fishers themselves, and partnering with their communities, we can mitigate the direct threat to key marine megafauna species and their most critical habitats, while supporting sustainable development in this amazing country.

Empowering community leadership in management and conservation is the most effective way for us to create generational improvements in marine ecosystems.

MANTA RAYS of Komodo

(previous)

(left)

showing

of Indonesian

(below) Overview

DR. ELITZA (ELLIE) GERMANOV, A SENIOR SCIENTIST AT MMF, IS A WORLD EXPERT ON MANTA RAYS AND OCEAN POLLUTION. She’s been working as a dive guide then manta researcher in Komodo National Park for years now, and recently published a major new scientific study on manta ecology in Komodo. - Simon Pierce

in conversation with

DR. ELITZA GERMANOV

SP: It’s my pleasure to talk to Dr. Elitza Germanov once again. Elitza manages MMF’s Indonesian country program, and also completed her PhD on manta rays, including the manta rays of Komodo. She’s just published a wonderful, foundational new paper on Komodo mantas, so I thought this was a good time to have a chat about what is going on there. So thank you, Elitza.

EG: It’s always great to chat with you, Simon.

SP: Likewise. When did you first see a Komodo manta ray? (Probably a good place to start.)

EG: Yeah. So, Komodo actually started my love affair with mantas. It wasn’t the first time I saw a manta, but I definitely had a memorable first manta encounter in Komodo. I was on a bit of a sabbatical, or a career break, from my

former studies in microbiology and immunology. I’d gone to Southeast Asia to do my Divemaster course. After I completed that, I booked a once-in-a-lifetime liveaboard to Komodo, a pretty budget-style liveaboard in the offseason. There was just myself, my now husband, and two other divers. And we chanced upon what appeared to be a massive feeding aggregation of mantas.

I didn’t know much about mantas then, just that they were big and that they were plankton-devouring filter feeders, so they weren’t dangerous. So I had no qualms about getting in the water amidst them all, and I was an amateur photographer so I was snapping away. It was only a while afterward that I found out manta rays have individual patterns on their bellies. Because a lot of them were feeding near the surface, a lot of my photos had actually captured their undersides as they rolled. So I came home with over 40 of these identification photos without even meaning to. I got interested in mantas because of this experience and found out that, actually, these photos are gold. I uploaded them all onto the online database for mantas, MantaMatcher. So that’s how it all started, and I was so fascinated after my time in Komodo that trip that I decided to find a job so I could work there. I applied to the few dive centers that were operating there at the time and got hired by one called Dive Komodo. I worked there for over three years. I had a supportive boss who saw that I was keen on the mantas, and allowed me to bring a camera when the conditions okay so I could continue to collect identification photos, and also to spend time activating the local community to do the same –encouraging people from the other dive centers, as well as the customers that joined our boat. So I basically started a citizen science project.

SP: I like that attitude, “Yeah I did this once-in-a-lifetime thing, it was really cool, so how can I do this all the time?”

EG: Yeah. It’s pretty much how that worked.

SP: So you got that rolling; when did it evolve into a more formal research project?

EG: A few other serendipitous things happened along the way. I got a chance to meet a dive center owner, Tim Birkett, who owns the Big Fish dive center in Nusa Lembongan, within the Nusa Penida Marine Protected Area. He was like, “Oh, you should meet my friends, Peter Bassett and Helen Mitchell; they’re also really keen on mantas, and they’ve been collecting manta bellies too.”

This was around 2012 or 2013, when manta rays were still actively being fished in Indonesia. In fact, Indonesia was in the top three countries for manta and mobulid trade worldwide.

We were each collecting these photos, which was helpful information for both Komodo and Nusa Penida, but we thought, “Why don’t we start comparing our different data sets to see if we find some of the same mantas.” I mean, the distance between the two areas is about 450 kilometers, so it wasn’t unimaginable that mantas were traveling between the two, and we knew that there were significant fisheries that were happening in between.

I had less than a hundred mantas in my database at that stage, but right away we identified three matches with the Nusa Penida mantas. That was important evidence for movement that a lot of the organizations working towards manta protection in the country needed, so we presented it to them, and they told us it was key information – the government knew that they wanted to protect mantas, but they weren’t sure whether they needed to do a full

Curious Komodo manta ray

Photo by Jerry Arriaga

nationwide ban on their fisheries, or whether it’d be enough to set up protected areas in places that were known to be important for manta rays. Seeing that they were ranging between these two established protected areas helped to push the government to fully protect the species in 2014. So that was the first little success that came out of the citizen science story.

Through working on this research, I met Dr. Andrea Marshall from MMF, and I expressed my hope that I might turn this into more than a passion project. I wanted to do more for mantas, and potentially even continue my studies. She took me under her wing, and I enrolled in a PhD program looking at mantas in Komodo and Nusa Penida: their ecology, their habitat use, and the threats that they are facing. This once-in-a-lifetime opportunity rolled into a career path.

SP: Awesome. You mentioned, “Yeah, it was a little success to have” there. It was a pretty major success to get at that stage of the game! Of course, that’s what we most want to achieve, to make our work impactful, so it was amazing to start with a result like that. That’s genuinely made life a lot better for the mantas.

EG: Yeah. It was good. Still a favorite story.

SP: It’s a good one. So, have you seen much ongoing connectivity between the two protected areas?

EG: Our manta database is sitting at about 1300 individuals now, even though we’ve had limited ability to survey over the past two years because of the COVID-related reduction in tourism – these programs really depend on our partnerships with dive centers for us to get on the water. Even as the database grows, it still seems that it’s about 1% of mantas making these movements. I’m unsure whether it’s because not many swim that distance, whether we aren’t surveying enough, or perhaps they aren’t always going the full distance.

Other research studies have used satellite tags and shown that they move along the coast between Bali and Komodo. There’s a large island called Sumbawa in between, and the mantas tend to go there from both Bali or Komodo, so it’s very likely that there are other aggregation sites along that coast. Just because the mantas are not constantly coming all the way over here to Nusa Penida doesn’t mean that their habitat range is constrained to those two areas.

SP: Well, that will be a fun area to explore. Do divers see many mantas along the Sumbawa coast?

EG: A few more dive operators started popping up around Sumbawa from 2019, and low and behold I started getting submissions of IDs from those areas. So yeah, it’s definitely something that I can follow up on; there are likely other aggregation sites that are not well known, or rarely visited.

SP: So, in contrast, Komodo is one of the older national parks in Indonesia, is that right?

EG: Yeah, it was initially set up in the 1980s to protect the Komodo dragons. I think the marine part of it came a couple of years later. There was a big difference in how it was managed from the late 90s and early 2000s, when very active patrols began, and there’s been good documentation of the reduction of destructive fishing practices like bomb fishing, so coral cover has improved since then.

SP: Do you think the park might have helped to buffer the impacts of those manta fisheries you mentioned?

EG: I believe so. There are a number of restrictions on the type of fishing gear that’s allowed to be used in the park. So even if illegal fishing still occurs, it will be at a lower rate, because there are more eyes on the water to report it. We do see about 5% of Komodo’s mantas still having some evidence of contact with fishing gear, but it’s not necessarily happening in the park;

(right) Ellie processing plankton samples.

(below) Manta ray at the surface. Photo by Debbie Arriaga

it could be happening outside. I think that not having gill net fishing, and having avoided fishing on sites where we know they aggregate, definitely will have helped.

SP: Having dived there for a long time yourself – and also working with dive professionals that might have been there for longer – is there any local perception of population increase, decrease, or stability over time?

EG: That’s a good question. I don’t recall anyone saying, “Oh, there used to be more mantas before”, or anything like that. But there are some other sites, which are rarely visited these days for whatever reason. Maybe because they require more advanced divers, or maybe because they are a little further away than other sites. For example, there’s an island just outside of the Komodo National Park, Gili Banta, which was at one point proposed to be within the park. I’ve heard from some of the long-term operators that there used to be, and hopefully still are, pretty reliable aggregations for mantas there. But it’s not in the park and, unfortunately, it serves as a jump-off point for fishing in the waters around the park. So that’s one of the areas where it’d be good to do further surveys and see whether these aggregations are still intact, and perhaps to find out whether there’d be interest in including this area in the Komodo National Park to add an extra level of protection.

SP: If it does turn out to still be an important area for mantas, that would be a strong justification for expansion – mantas have become quite an iconic species at the park now, haven’t they?

EG: Oh yeah, for sure. It’s one of the top sites in Indonesia to see reef manta rays. It brings in a lot of blue economy money to the area.

SP: And you can see them either diving or snorkeling over there?

EG: And all year round, pretty much.

SP: As you mentioned before, COVID obviously restricted the number of tourists that were allowed to enter the country, as well as people traveling in general over the past couple of years. So less data were coming in, and there were

fewer eyes on the water as an informal patrol service. But, also, there were fewer tourists in the water. How do you weigh up the benefits and potential negatives of tourism in your mind?

EG: Yeah. I’m part of WhatsApp chats between the community members, and I’ve seen posts of fishing activity happening in the park; I guess there has been less budget for patrols. It seems that some of the fishing activities became a bit bolder and went to sites where they normally wouldn’t fish; not necessarily manta sites, but reef sites where we do sometimes see mantas. Some very iconic sites in Komodo have been fished over the past year or so. That’s one of the negatives of not having eyes on the water.

But, on the other hand, tourism had significantly increased over the past 10 years. Over four years of our direct monitoring, there was a 30–35% increase in boats at some of these sites, and it was becoming unsustainable. You could tell that the encounters we were having were shorter, that mantas were visibly bothered. They weren’t their usual curious selves; they were in a hurry to go. So whether that’s because of more boat noise, or the disruption of having all those divers in the water, especially around the cleaning stations, it’s hard to say.

In other parts of the world, there have been studies showing that snorkeling with mantas can disturb their natural feeding behaviors, and can cause more avoidance behavior from the mantas. That’s all eating into their energy reserves. If a preferred habitat is no longer able to provide the food, the nourishment they need, or allow for other important activities like courtship and mating, then maybe mantas will have to move to lower-quality habitats. For a species that’s slow to reproduce, and still threatened with extinction, any extra pressure is something that we need to consider.

The Komodo National Park staff had realized this already, and they did some carrying capacity studies in the years leading up to 2019. Some limits were placed on one of the most famous sites for mantas, called Karang Makassar or Makassar Reef, a shallow rubble reef with several coral bommies over which you can see mantas rays cleaning. It’s usually done as a drift dive, and it’s quite a large area, over a kilometer long. They’ve placed a limit on the number of boats that can use that site per day now, and the number of divers. Whether those limits are sufficient is yet to be seen, because

these regulations came into effect in September 2019, and things have been disrupted by COVID through the 2020–21 seasons.

I hope that this study that we put out recently, which details this increase in tourism, and also the importance of these sites for manta rays, will encourage buy-in from the operators. Hopefully, it’ll allow them to see that these are important areas and that, as their livelihood depends on healthy manta ray populations, then it’s a good idea to have these limitations in place, even if they might seem inconvenient at first.

SP: Yeah, for sure. And certainly with mantas, I’ve always found that if you’ve got unbothered mantas, then they are likely to approach people more. Which-

EG: Gives better experiences.

SP: Exactly. It always feels a lot better to have the animal approach you, rather than have people chase them, as mantas can swim a lot faster than divers. So, if you don’t just want to see their tail, then it’s good to let them come to you.

EG: And a lot of that is in the hands of the operators, to provide good briefings to their guests about how to have the best manta encounter, which is good for the manta and for the divers themselves, as it will result in much better and longer encounters.

SP: Did you identify other sites in the park that are disproportionately important to the mantas?

EG: Definitely. We surveyed over 30 different sites, and four really stood out as places where you can regularly see mantas. None of them were a real surprise, as dive operators know these sites and specifically go to them to show mantas to their guests. But it was incredible to see how many mantas actually use these sites, and how the sites are used slightly differently. It seems individual mantas have their preferred areas, while different sites are preferred at various times, or by different demographic groups or age classes.

SP: So is it the same mantas that are moving around, or different mantas doing different stuff in different places?

EG: If you start digging into the mantas’ sighting records, you see that some mantas are only seen in a specific place.

We call them the homebodies. Others, the jetsetters, often move around, even to Nusa Penida and back. So there are definitely some individual-level differences; whether that’s due to social structure, age, or other factors is still an open question.

SP: Are you seeing much evidence of breeding activity within the park?

EG: Totally. I was on a trip with Andrea a couple of years ago and saw some really cool mating trains. So basically, when mantas are trying to reproduce, the females make the males compete. You have these trains of sometimes 15 males chasing the females – or the females may be encouraging the males to chase them, we’re not really sure exactly how it works. She becomes very acrobatic, with very quick changes in direction and turns, and the males have to keep up. I guess the last man(ta) standing gets the trophy, and gets to mate with her. When you’re actually witnessing this, it’s simultaneously frantic and beautiful. We’ve seen that happening in at least three sites.

SP: You mentioned earlier that about 5% of the mantas have fishing-related injuries at this point. Is fishing still a significant threat to the mantas?

EG: 5% is lower than some other locations. For example, in Florida, I think it’s over 30% of mantas that have some fishing-related injury, or are swimming around with embedded fishing hooks and things like that. Mantas have a soft cartilaginous skeleton so, when these lines get entangled around their cephalic lobes, which are used for feeding, or around their fin tips, which is where a lot of their propulsion comes from, they can be sliced off. That inhibits their feeding or swimming, forcing them to work harder and expend more energy to get the same result. That’s energy that could have been used for reproduction, which is what helps their populations rebound. Relating it to Nusa Penida, there we have about 13% of the mantas bearing injuries. So the Komodo mantas are faring better.

SP: Assuming that the park can get a handle on the tourism, then, it sounds like the protection from 2014 should be effective at helping the population to recover?

EG: I hope so. I’m optimistic.

THREATS

ARTISANAL FISHERIES

manta rays use Cauldron.

THREATS

ARTISANAL FISHERIES

5% of manta rays trail fishing gear or have permanent injuries number of boats on site has increased by 34% from 2014-2017

5% of manta rays trail fishing gear or have permanent injuries

EXCESSIVE TOURISM

EXCESSIVE TOURISM

number of boats on site has increased by 34% from 2014-2017

CONSERVATION

CONSERVATION

Proposed management actions include: restrictions on the number of tourism boats, area closures, enforcement of diver conduct codes and no fishing regulations

Proposed management actions include: restrictions on the number of tourism boats, area closures, enforcement of diver conduct codes and no fishing regulations

m

≥ 3 m

based on designs by Giulia De Amicis

SP: That’s always a good place to be. So moving on then from this epic paper, what are your next steps for research?

EG: We need population and abundance estimates next, so I’ve already started prepping the dataset, and I’m learning how to do the modeling. There are lots of Greek letters involved, but I’m up for the challenge. And there are people within MMF that already know how to run these analyses, so I’ll be leaning on them for sure.

SP: That’s fantastic. You were saying there might be a few places outside the park that are important to mantas as well. Have you got any exploring planned?

EG: Yes. There’s a resort on Sumbawa that dives at Gili Banta, that island that I mentioned earlier, so we’re heading there in November to see what we might find. The idea is to try this trip at a couple of different times of the year. If we find some mantas there, we’ll be able to see if we’ve identified them in Komodo or Nusa Penida. We still don’t know much about where the young mantas are either. There’s one site in the north, Cauldron, where we see smaller mantas. We know from Nusa Penida that site use, over there at least, is quite segregated between age classes. At one site, Manta Bay, we see a lot of younger mantas, and males as well, which are smaller than the females, using the same area. At another site, Manta Point, we rarely see juveniles. That’s what is going on in Komodo too, where there are three main cleaning station sites. We see juveniles there once in a while, but most are adults, but then at Cauldron we have some smaller mantas. There should be more of them

around than we’ve seen so far, perhaps in other bays in the northern part of Komodo or nearby islands.

SP: It’d be nice to find a few more of the babies, if they are more in the area, since Manta Bay has proven to be such a great study site.

EG: Exactly. And in Penida, we are doing some follow-up studies, with Janis Argeswara leading a project to look at reproductive ecology: identifying when mantas are mating, when pregnancies can be seen, and the percentage of the mantas that are pregnant. She’s also looking at the younger mantas to find out if they were born within the last year or not. To do that, you need a good measurement, so we’ve been piloting a methodology called stereo photogrammetry, where we sync two cameras and calculate manta size based on the discrepancy in the images. Once Janis gets that up and running, it might be something that we can take to Komodo and elsewhere to really dig into manta demographics.

SP: Fantastic. So people should check in with you after November to see if you’ve got trip number two planned.

EG: Yeah. The first one’s full, so that’s great – I had a really supportive group of people who wanted to help make it happen, because it was a dream that I had. Then COVID poured cold water over it but, finally, we’ll get there this year.

SP: Well, thank you very much for joining me again, and for explaining your research to everyone.

EG: Thanks Simon, it’s always a pleasure. Bye everyone.

(right) Manta tourism.

(below) Manta on a cleaning station.

WHALE

SHARK ECOTOURISM

in Mexico

(previous) Whale shark and swimmer off Mexico.

(left) Beachfront at Cancun.

(below) Close approach to the research boat

a trip report by DR. CLARE PREBBLE

I was very pleased to be part of the triumphant return of Aqua-Firma to Mexico this year to see the Yucatan Peninsula whale shark aggregation. Post plague, the logistics of the trip had changed slightly, and this was also the first time that both Charlotte Caffrey of Aqua-Firma and I had hosted the Mexico trip. What could go wrong!?

Spoiler alert – not much – it was actually amazing!

Team 2022 assembled at the Playa Mujeres beachfront, north of Cancún, at the decadent all-inclusive hotel that was to be our base for the next week. We were a Goldilockssized group of ten, with a diverse range of backgrounds and ages. Some had been trying for a decade to see whale

sharks. Others were seasoned hands, having traveled to multiple aggregation sites worldwide. So, no pressure then… Day one on the water was preceded by an introduction to our fearless boat captain and whale shark researcher extraordinaire, Rafael de la Parra. Rafael has been working in the Mexican Caribbean since 1988, and has been studying whale sharks there since 2004. So of course he’s been captaining the Aqua-Firma trips to Mexico since they started in 2013.

Our first day was a scorcher, but the waves and the wind were in our favor and we reached the whale sharks after about an hour. All the sharks were frantically feeding at the surface, some at quite a pace. Everyone managed to get several swims with the sharks, along with a bit of a workout (helpfully counteracting the hotel meals). There was also a brief sighting of a dark melanistic ‘ninja’ manta, and a striped marlin. An excellent first day!

By day two, everyone had their sea legs and whale shark spotting eyes tuned. We were greeted by wonderful chaos as we arrived at the aggregation. Tens of whale sharks were clustered together surface feeding. We were even treated to some vertical feeding behavior as well. Once in the water, there was no need to swim anywhere. Whale sharks swooshed past us left and right, quite often at the same moment. This day was hence known as ‘whale shark soup’ day. Rafael was like a giddy child, exclaiming that it was the best day of the season so far. He also told us that the world’s most famous whale shark, Rio Lady, was amongst the throngs of sharks in the water. Rio Lady is a large ~7.5m female shark

CLARE PREBBLE IS A SENIOR SCIENTIST AT MMF, and just hosted her first trip to Cancun, Mexico, with our travel partner Aqua-Firma.

that has been tagged multiple times, most recently off Isla Mujeres in 2018, traveling a record-breaking 19,000+ miles since then. She has been far out to sea in the western Atlantic and all the way south towards the coast of Columbia. Rafael informed us that her tag had transmitted a few days earlier in the Gulf of Mexico, and that she had now returned home to the Isla Mujeres Afuera aggregation.

After a well-timed rest day, the group set out on the calmest day yet. With the lake-like conditions, we spotted two whale sharks early in our journey toward the aggregation, and kept them both to ourselves! Clear water, relaxed whale sharks, and early morning light made for excellent photography opportunities and relaxed snorkeling sessions for everyone.

With everyone (almost) sated with whale shark encounters, our final day on the water started strong with several loggerhead turtles spotted on the surface and almost 45 minutes of a spotted dolphin pod bow riding and jumping in the wake of the boat. On arrival at the feeding aggregation, it was clear that the whale sharks were very spread out and generally staying below the surface. Not wanting to add to the boat: shark ratio, and with the previous days’ experiences in mind, the decision was made to head out towards Isla Contoy. Here, due to the upwelling and currents, the waters

are cooler and murkier, but it’s often the best place to spot manta rays. We did manage to spot some eagle rays, bottlenose dolphins, and got a quick glimpse of a manta ray. The leisurely journey around the island was stunning, but the slightly quieter marine life sightings reminded us all that the ocean can be unpredictable and highlighted how special our experiences earlier in the week had been.

With smug faces and Vitamin D-enriched skin, the group all had a final dinner together to toast our luck and plan where to go with Aqua-Firma next – except one couple, who were smugly heading off on a magical whirlwind tour of the peninsula to see monkeys, flamingos, and magical forested Mayan temples. (I’m not jealous, you’re jealous). Charlotte and I bade farewell to all and agreed that we were so lucky to have had such an easygoing group that marveled at the sea just as we do. Bring on Mexico 2023!

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