Published 28th November 2008

At the Southern tip of Africa a deadly game of cat and mouse is played out over and over again in the salty waters off the fabled Cape of Storms. Each Southern hemisphere winter, between May and September, the infamous white shark makes its appearance known through spectacular airborne breaches out of the inky depths around Seal Island in False Bay (Western Cape, South Africa).

It is well known that at Seal Island the white sharks patrol the breeding colonies of Cape fur seals and their general hunting strategy involves swimming at depth to launch ambush attacks on the seals above, whose dark bodies are silhouetted against the light of the ocean’s surface. However, the range of tactics used by both predator and prey in this game of catch and be caught - or miss and survive - have until now remained a mystery.

In a paper published in the October issue of the scientific journal Animal Behaviour a team of scientists from Simon Fraser University, the Save Our Seas Foundation (SOSF) and Marine and Coastal Management Branch of the Department of Environmental Affairs explain what variables drive the tactical decisions of both shark and seal. A seal’s swimming and foraging behaviour tries to minimize the risk of being eaten by a shark; dicing with death, their strategy is aimed at avoiding attack. The sharks patrol using tactics that maximize their chance of killing; driven by hunger their payoff is a calorific, blubber rich meal. Karl Laroche, the lead author explains, “The optimal course of action for either species depends on the other’s behaviour.”

The breeding colony at Seal Island has a year-round population of between 36,000 and 77,000 seals, made up of an age mix from pups to breeding adults. With both pups and adults travelling from the colony to feed in open water and returning to rest or nurse, the shark population, so it seems, is spoilt for choice. The team’s findings challenge traditional studies that consider predator and prey as uniform groups. Their study suggests that seals may not be equal players in the game, because seals of different ages exhibit a very different set of behaviours around Seal Island.

The seals, which may stay away from the colony for several days or even weeks, appear to be at most risk from shark predation in the area between the shallow waters adjacent to the colony and about a distance of 1,000m out to sea. Well aware of the seals’ movements, the sharks concentrate within several hundred metres of shore, and the seals, well aware of the risk, select the best movement tactic to run the gauntlet.

Both species base their game tactics on variables such as location, swimming depth, and the timing of departure and return. In addition, seals have another card up their flippers: the option to choose the size of group they travel in. Seals of all ages depart in large groups within two hours after sunset by porpoising in a southerly direction at the surface from the south side of the island. Group swimming ensures safety in numbers on departure, but because coordinating large groups requires synchronized timing and seals are solitary feeders they often return to the island alone or in small groups. Most adult seals choose to return to the island under the cover of darkness, swimming at depth to avoid being conspicuous at the surface.

The majority of pups return between 7 and 9 am, alone, around sunrise, over the deeper waters of the southern and western sides, and spend considerably more time swimming at the surface than the adults. The study revealed that it is precisely these variables that produce the greatest probability of attack. “It appears the pups do not account for risk in choosing their game tactics and the fact that sharks concentrate in the morning, mid-water, to the south suggests that sharks focus primarily on the seals playing a high risk game,” says co-author and SOSF scientist Alison Kock. The return movement of seal pups explains why shark hunting tactics seem more influenced by the riskier behaviour of pups than adults.

The question remains, with the stakes so high, why do pups play such a risky game? The scientists are perplexed. Perhaps, it is naiveté or a miscalculation of timing, or perhaps it is a trade off that avoids another risk. One thing, however, is for certain, white shark numbers at many locations are plummeting due to over-fishing, and it is studies like this one funded by the Save Our Seas Foundation that are essential for learning more about these apex predators before it is too late.

For more information on sharks visit: www.saveourseas.com

‘Rethink the Shark’ highlights the fact that faulty toasters kill more people each year than sharks do.

"It's very heartening this year to see so many films with a strong environmental focus – it seems at last the environment is going mainstream, and is on everyone's agenda," said Joanna Lumley, the host of this year's Oscars of the wildlife film industry.

The Gala Panda Awards in Bristol took place last month amidst a week of seminars, debates and discussion at Wildscreen, the leading wildlife film festival. It attracts delegates from around the globe who work in film, television and the press, as well as those actively involved in working to conserve the environment. Over 420 films were entered.

A definite buzz filled the air at this year's Festival and the big 'C' word was on the lips of most producers, commissioners, cameramen and NGOs.

A swear word on the tongue of some and the planet's only hope in the voice of others, the big 'C' in the wildlife film industry stands for Conservation.

Every film-maker wants the audience to care passionately about their story to the extent that they feel moved to take action and make a difference, but from Sir David Attenborough and James Lovelock to the Director of Google Earth, it seems everyone is perplexed as to why environmental films with strong conservation messages are not making it to the light of day.

Sadly, those that do are destined for the ghost slots, late nights on channel Z while prime time TV is sandwiched with big teeth, blood and fear.

One character that almost always comes worse off in these adrenaline documentaries is the shark. A never-ending series of natural history films (perhaps natural history entertainment is a more apt description) portray sharks as man-eaters.

By perpetuating the 'Jaws' myth these films do nothing to promote shark conservation and the cruel fact that man is killing 100 million of them each year, pushing sharks toward their final cut – extinction.

In one giant step towards promoting natural history films that tell the whole story and engage viewers with the big 'C', the Save Our Seas Foundation (SOSF) took home the most prestigious award in natural history filmmaking – the Panda Award – for its campaign film 'Rethink the Shark'.

A great campaign film considers the audience, provides a key message in a compelling way, and hopefully challenges preconceptions. According to the judges SOSF's 'Rethink the Shark' did this with "a sharp eye for detail, extreme wit and good humour."

SOSF, in partnership with Saatchi and Saatchi's Cape Town division of the global advertising agency, created a film that ends the stereotypical view of 'Jaws'- with an ironic twist.

Drawing from its scientists around the world SOSF's HD films are based on cutting edge research and designed to educate, delight and inspire the audience to take action and conserve our marine environment.

A summer's day on a crowded beach: shrieks of delight and joy sound the air as children splash and play in the ocean. The happy, family scene turns sour as a woman screams and panic ensues. People swim frantically for the shore, there is a stampede on the beach and a baby, almost trampled in the chaos, cries.

Am ominous shape appears – a toaster floats towards the panicked spectators, its triangular edge bobbing above the surface, and the audience gasps as reality hits the screen: "Last year 791 people were killed by faulty toasters. Only 4 by sharks. Rethink the Shark".

The film, part of an awareness campaign driven by the SOSF, urges people to 'Rethink the Shark'. It challenges the media-driven public perception of sharks as man-eaters to looking at these key ocean predators in their real light.

SOSF is a non-profit research and education organization that is dedicated to raising awareness about the state of our oceans and highlighting the negative consequences of removing sharks and rays from the marine ecosystem.

Cape Town, where the scene was filmed, is home to the Save Our Seas Shark Centre, which promotes the protection and conservation of sharks worldwide by developing scientific research projects and global education and awareness projects that target the general public, fishers and children.

So, next time you crisp your bread spare a thought for the sharks out there that are rapidly becoming toast due to over-fishing and finning.

For more information or to download 'Rethink the Shark' visit: www.saveourseas.com

Cool Seas Road Show Inspires Children to Care about our Oceans

Sea fever is rapidly spreading through the country’s school children. From Cornwall to Scotland, the Isle of Man to Ireland, kids as young as four years old are learning that British seas are just as cool as those in the tropics, in fact more so. I visited Andy Starbuck earlier this month to find out what the Cool Seas Road Show (CSRS) was all about, and arriving from a world of environmental doom and gloom, I left the classroom feeling inspired by the power our future generations hold to save our seas.

The Save Our Seas Foundation (SOSF) together with the Marine Conservation Society is a major sponsor of this inspiring initiative. SOSF implements and supports a diversity of scientific research and education projects focused on the marine environment, particularly focused on sharks and rays.

The CSRS is an educational presentation designed to raise public awareness of our oceans and the diversity of marine life off our shores. County councils encourage it as part of a greater environmental education program within local schools, and each council often emphasizes a particular theme, which Andy highlights in the Show. Priceless expressions of wonder and delight light up on both children and teachers as they enter their school hall filled with life-size models so life-like that they could be real were they moving.

Starbuck presents the Show several times a day at one school, adapting it in length and content for the different age groups. A prop maker for TV and theatre before turning his hands towards sea creatures, Starbuck makes and hand paints all the inflatable marine models used in the CSRS. The school halls are normally not large enough to accommodate all his creations, but on my visit he had managed to squeeze in more than even Mary Poppins herself could have managed. Included were a juvenile and adult bottlenose dolphin, a common dolphin, a porpoise, a minke whale, a grey seal with her pup, a leatherback turtle, turtle hatchlings, a basking shark and a great white shark!

The students were thrilled to learn that cold water harbours more variation of life than warm water, that all of these creatures live in British waters, and that there is a good chance that they could see some of them if they took the time to watch from their own town pier. Working his way around the hall Starbuck teaches the kids facts about each charismatic animal on display. Wide-eyed, the kids gasp at the size of a mother bottlenose dolphin compared to her small calf and learn to distinguish between the different species through their markings and dorsal fins. Starbuck encourages the children to reconsider their ideas of marine life, such as considering dolphins to be not so unlike us, mammals, rather than “fishy creatures.” The sharks are undoubtedly the boys’ favourites, but they were all surprised to learn that falling coconuts kill more people each year, and that even though one pupil could fit in its mouth, a basking shark is a harmless plankton eating fish. I talked to some of the pupils after each session and with over 100 million sharks killed each year by humans it was refreshing to see perceptions changed at such a young age. One boy announcing to me that he “was not so worried about sharks anymore!”

After being introduced to each species the students are taught how the animals depend on a multitude of smaller creatures, from smaller sharks and fish to jellyfish, plankton and algae, and that these are all needed to make up our amazing and complex cool seas ecosystem. Audience participation allows several children “on stage” to run through a series of role-plays, including acting out conservation workers helping turtles hatching. The pupils love it; they learn how vulnerable the hatchlings are and it illustrates how we can all make a positive difference towards saving our seas if we all work together.

The Show, however was not made in fairyland and the children are taught some of the adverse effects humans have on our blue planet, especially regarding litter. Analyzing a collection of plastic rubbish, including plastic bottles, bags and empty helium balloons, found on a nearby beach and explaining how it could kill turtles and dolphins, the kids soon realize that rubbish does not miraculously disappear.

During his two weeks in Brighton, Starbuck presented to 3,200 pupils, and in a typical year he presents to 20,000 children. “It is important to encourage the kids to carry on learning and to explore their own marine environment, and the experience lasts a lifetime,” says Andy. In fact Andy met an 18 year-old work experience student in one of the schools who remembered the CSRS at her school when she was only five. In addition, the Cool Seas books expose friends and parents to the cool seas, and the children take home a very powerful weapon: “Pester power”, which educates and coerces parents towards marine conservation and awareness.

Although 71% of our planet is covered in salt water and the UK is surrounded by this watery world, some children have never stuck their head beneath the waves, let alone understand that this fragile world goes far deeper than the visual, blue and grey rolling waves upon the surface. “The CSRS enables kids a hands on exploration of a world that is for most part, off limits; this helps kids experience, understand and gain a greater appreciation of the marine environment, which is why SOSF is proud to be involved,” says Chris Clarke, director of the SOSF.

For more information on the marine environment visit www.saveourseas.com

A second, and possibly third, species of manta ray has been discovered in the World’s oceans. This is the biggest news to date to come out of ray research, and its importance is the marine equivalent of discovering an unknown species of elephant. The discovery however, has implications that go far beyond the breaking news of scientific journals, as it will deeply affect real world conservation ideas and policies.

For the past five years the Save Our Seas Foundation (SOSF) has sponsored Andrea Marshall, a PhD marine biologist in a quest to make advances in the scientific knowledge of these winged beauties of the sea, whose large triangular pectoral fins can span almost 8m in width and whose weight can reach over 2000kg. Manta rays, which are totally harmless and do not possess a stinging barb, are the largest of over 500 different species of rays and skates, and although divers have noted variations in physical appearance they were previously believed to be the same kind.

After suspecting the existence of a second species Andrea began studying other populations across the globe. Through genetic and morphological analysis she confirmed that there is indeed a second, and possibly a third, species of manta ray that exists across temperate, tropical and subtropical waters worldwide. The two species have mainly overlapping distributions, but their lifestyles differ greatly; one is migratory and the other is resident to particular areas along the coast. Other differences between the two species lie in their colour, skin texture, reproductive biology, and the presence of a non-functioning type of sting on the tail of one of the species.

The smaller, more commonly known manta ray, resides in the same areas year round and is often encountered at coral reefs where they congregate to be cleaned by parasite-eating fish in locations such as Hawaii, the Maldives, Mozambique, Australia, Japan and the Island of Yap. Due to their residential nature they face a grave threat from unsustainable fisheries, as other manta rays will not replace a dwindling population, making their regional extinction a likely possibility.

Far less is known about the larger species, as it appears to be more migratory and elusive, shying away from divers rather than seeking interaction as its smaller cousin often does. Andrea has only ever witnessed it arriving at sea-mounts or at particularly productive areas along the coastline to feed on plankton before disappearing into the blue once again.  Little is known about its behaviour or migratory patterns, though it appears to be targeted heavily by fisheries, particularly in Southeast Asia, where thousands are killed each year.

The discovery of two distinct species has huge implications for the conservation management and protection of these mysterious gentle giants. The larger, ocean wanderer knows no borders, making collaboration between countries on its protection essential, whereas protective measure within countries must be enforced to avoid resident manta ray populations crashing. Habitat degradation, harassment by boat traffic and even divers who interact with them at critical habitats such as cleaning stations and breeding areas are other threats these graceful animals face. They also fall victim to ghost nets and are killed alongside many other marine creatures as by-catch.

Andrea’s obsession with sharks travelled with her from the tender age of five until university when she discovered how little was known about their cartilaginous cousins, manta rays. Undeterred by the difficulties such research would involve she sold her belongings and in 2003 moved to a small coastal village in southern Mozambique, to become the first marine biologist to study manta rays off the African coast. Through her observations of the unique spot patterning on the ventral surface of each ray Andrea has identified over 900 individuals on a single reef, and she believes southern Mozambique may boast the largest known population of manta rays in the world.

Discoveries about the reproductive behaviour of these highly social and inquisitive creatures have also been an important outcome of Andrea’s research. Manta rays are now known to give birth to a single large offspring of about 1.4m after a year of gestation and, once reaching maturity at about 4m across, typically produce a pup every other year. Elaborate and sophisticated courtship displays are performed and they may communicate with one another using specific body posturing and perhaps sound.

SOSF aims to learn more about the role of marine species, particularly sharks and rays, and through this knowledge it hopes to raise awareness and conserve the marine realm. Andrea’s many hours underwater have produced information critically needed for the protection of these threatened animals. We now know that there are at least two species, but we need to know a great deal more about their population structure and distribution so that we can devise and implement improved protection measures.  

More than the Big Blue
Celebrate the Ocean TODAY and help Save Our Seas

There is far more to the big blue than meets the eye. In today’s fast pace life that struggles to find the time to look past the obvious, many people believe that if the ocean looks blue, rises and falls with the tides and continues to roll out its waves all is as it should be. Sadly, they could not be further from the truth, as our oceans and their inhabitants are in big trouble and ocean environments around the world including South Africa’s two oceans are threatened primarily due to over-fishing, unsustainable coastal development, climate change and pollution. Despite covering more of planet Earth than earth itself less than 1% of our oceans are protected in reserves, by comparison 10% of land is protected by parks.

To those who do not know the ocean and have never donned mask and snorkel to discover the wonder below the waves our ocean realm is a deep, dark and menacing place. This World Ocean’s Day challenge yourself to transform your thoughts about the marine realm, which covers more than 70% of our planet’s surface, to that of a beautiful playground of life worthy of respect and protection. Rethink the image of sharks, for they are not the man-eaters of myth and legends but top predators in the ocean food chain that regulates the populations of species below them. As sharks’ numbers are plummeting to the point of extinction a cascading effect is threatening to tip the balance of our oceans into a negative state.

Published on the 6th May 2008

This is the final posting from conservation biologist and photographer Cheryl-Samantha Owen who has been working with the Save Our Seas Foundation (SOSF) on the Aldabra Atoll to document the abunance of large shark species.

The rough seas of the monsoon season can make it difficult to get off the Aldabra atoll but the Save Our Seas team found themselves wishing for even tougher conditions, making it impossible

Standing closer to the bow than the rest of my expedition team, which sat huddled in wet t-shirts at the back, the ocean’s salty spray lashed at my eyes with each breaker that washed over us and I could see every wave that loomed ahead, magnified ten fold in my blurry vision, before we climbed it. Our Seychellois captain had many years of ocean tales to recount and I assumed he could see more sea than I. While rubbing his eyes in a futile attempt to keep them dry, however, he announced: “You never can tell which waves the boat will glide down or which ones we will fly off”, and my knuckles paled a shade whiter. We flew off quite a few, but considering the battle between the current and its opposing 35knot southeast wind staging all around us the four-hour journey from the Aldabra Atoll to Assumption Island went relatively smoothly.

During this monsoon season research scientists on Aldabra are often unable to get safely off the island for months at a time, and watching Aldabra gradually fade into the blue, I couldn’t help but wish I were one of them. How do you breath in – freeze frame the memories of an expedition to a place so far removed from most places on Earth today that it feels like another, forgotten, world? More importantly, how do you take Aldabra to the rest of the world? The Save Our Seas Foundation has joined forces with the Aldabra Foundation to do just this. Our expedition footage and photographs will be become part of an exhibition, travelling to cities worldwide in an effort to raise awareness of the extraordinary natural paradise that still exists on Aldabra and in its surrounding waters.

Back on Aldabra I realized as I watched a little blonde 4 year old, the daughter of Aldabra’s research officer, splashing in the sandy shallows with blacktip reef sharks swimming nonchalantly past her, that this is how it is meant to be. Day by day the atoll revealed more and more of its treasures to us, and with them uncovered a forgotten past that has existed here, unaffected by human influence, since the age of reptiles, millions of years ago. That existence, which once belonged to every tropical reef and mangrove forest on earth, still remains on Aldabra today. Over time these portholes back in time have been narrowed down to a few fragmented protected areas, and most people will never experience first hand planet Earth in all its glory revelling in a life undisrupted by humans.

Even though statistics show that New Yorkers bite more people than sharks, sharks have suffered terribly at the hands of man, and with more than 100 million killed each year, we are busy wiping a group of animals that has survived since before our existence to extinction. The world needs people to appreciate the intrinsic beauty of sharks and their absolute necessity for maintaining a healthy ocean, and I hope that what we found and have brought back from Aldabra will inspire people to go against the ingrained media driven perception of sharks. 

We went to Aldabra to document the abundance of large shark species. What we found in a place termed ‘the most inhospitable place on earth’ was one of the most hospitable places in the sea for inshore shark species. Inside the lagoon and fringing reef the blacktip reef sharks proliferate in high numbers – they were everywhere on all our inshore dives. Given time, the sicklefin lemon and gray reef could also be counted on for an appearance, both in the lagoon channels and on the reefs, and on a couple of occasions we were graced with the presence of elegant silvertip and whitetip sharks.

Outside the protection of the reef our search for pelagic shark species revealed empty blue water, and considering the amount of bait we used, which can be detected by sharks miles down current, it looks as if they have vanished from the surrounding waters. Reports of tigers sharks in the lagoon haunted us day and night but these gray ghosts with their vibrant tiger stripes eluded us. We cannot say with certainty there are none left, perhaps those that have survived the long lines of baited hooks in the surrounding waters were hunting turtles in the more remote and inaccessible parts of the lagoon or perhaps they were further a-field; Tiger sharks have been recorded migrating between Australia and South Africa. Another explanation is that they are active more at night on Aldabra, but even if one of these possible theories is correct the numbers are still drastically low. As for the other oceanic species, such as oceanic white tip and the great hammerhead, there were none there for us to photograph.

The words of greatest naturalist George B Schaller could never be more poignant than in this day and age: ‘Pen and camera are weapons against oblivion; they can create awareness for that which may soon be lost forever.’ I hope that the images we have come away with of the magic we did find, of a land and ocean living as it is meant to be, will help to fill in and repopulate the blue voids of the places that have lost their life.

Visit http://www.saveourseas.com to learn more about SOSF, the marine environment, and to read my daily blog of the Aldabra Expedition.



 

Conservation biologist and photographer Cheryl-Samantha Owen is working with the Save Our Seas Foundation (SOSF) on the Aldabra Atoll to document the abundance of large shark species in the surrounding waters. 

Like the hare, the Aldabra White-Throated Rail, cannot fly. It has large wings, a characteristic contrary to expectations of flightless bird forms, but usually only fans them wide in a move to make itself look larger than life when defending its nest and chicks. Like the hare, the Rail can also leap - another use for its wings, but it is has long been considered the last flightless bird of the Western Indian Ocean Islands. Considering the fame attributed to the dodo, a flightless bird endemic to the Indian Ocean island of Mauritius, which man pushed to extinction in the 17th Century, the very much alive Rail deserves its share of the limelight.

Over the years humans and introduced predators such as cats, which have since been eradicated on some islands, have caused local extinctions and range reductions and today two subspecies survive, one on Madagascar and one on three of Aldabra’s islands. I met my first Rail shortly after arriving here on Picard Island, which thanks to a re-introduction of the species in 1999, is now running with rails, but I didn’t really get to know the Rail until we rode the rough seas to the northern side of the Atoll and camped in a place affectionately known as ‘middle camp’ a few days ago. Situated near the mouth of Pass Houareau in between the islands of Malabar and Grande Terre is a little wooden hut with a corrugated tin roof that crawls with coconut crabs scratching their claws across the tin, which screeches like nails down a chalkboard, all night, and clinks with dimorphic egrets catching insects in the guttering in the early hours of the morning. Sleep was not a priority anyhow as we were there to photograph the marine life of the mangrove forests and the frigatebirds and boobies nesting in foliage above.

A tropical down pour on our first morning at middle camp, forced us to shift gears slightly as the bad light rendered photography underwater in the dark mangrove forests impossible and I was left photographing this little bird, endemic to Aldabra on the coral rubble around the camp. Their breast musculature is simply too small for them to engage enough power for level flight, and they evolved on Aldabra in the absence of any predators as ground foragers without any apparent need to fly. Flightlessness does come with perks, as flight muscles are amongst the most energetically demanding organs in a bird, thus lacking them has energetic advantages, and one theory is that the original impetus for them becoming flightless may have stemmed from their need to store fat during periods of scarcity – making flight difficult.

Another character joined us on Malabar that has kept us company since our Save Our Seas Foundation expedition team first impressed footprints on this shore here. Slowly and steadily four elephantine legs covered in tough leather and etched with rough scales climbed over the crest of the beach slope from seemingly out of the blue and headed directly towards my toes. Aldabra’s very own giant tortoises are almost as old as the Atoll itself. They are the old men of the island, the equivalent of sharks in the marine world; they too survived millions of years prior to man’s arrival, and only thanks to the difficulty sailors had in penetrating this coral limestone fortress and the foresight of early conservationists do these herbivorous reptiles still dominate Aldabra’s living natural history museum today. Elsewhere they have gone the way of the dodo.
 
Like the fabled Tortoise this Aldabra fossil has so far won the race for survival and, in our camp at least, beat the Rail to eating most of our food leftovers. Despite the Rail’s beautiful rusty red and forest green feathers its attention span and dedication to eating paled in comparison to that of the tortoise’s, who sat wafting onion breath around our camp.

I hope that slow and steady will prove one day to win the global conservation race, but now we need to accelerate our pace in working together to help save our seas, especially the sharks who, although they have lived on our planet for millions of years, are struggling in this day and age to survive in the wake of their decimation by our species. We did eventually leave the tortoise and the rail and spent two magical afternoons on a high incoming tide photographing the mangrove forests, a shark and fish nursery ground that is crucial for the repopulation of our oceans.

Visit http://www.saveourseas.com to learn more about SOSF and the marine environment.

Conservation biologist and photographer Cheryl-Samantha Owen is working with the Save Our Seas Foundation (SOSF) on the Aldabra Atoll to document the abundance of large shark species in the surrounding waters.

Watching giant tortoises and gargantuan crabs crawl along the high tide mark scavenging washed up offerings from the sea, while shark fins slice through the surface of the deadly calm water beyond I feel as if I am sitting in a true Jurassic Park. This is after all, one of the Indian Ocean’s most remote islands and as such is relatively untouched by humans.

The geological nature of Aldabra has enabled a complete, isolated ecosystem to develop, incorporating all the key tropical marine habitats and processes. The volcano that became Aldabra emerged roughly 20 million years ago; a massive seamount rising from the sea floor it is the island’s foundation. As the volcano ceased to be active it gradually subsided and the coral growth on the 35km wide limestone ring maintained contact with the ocean’s surface, leaving a huge circular reef structure. This process is what made Aldabra the World’s largest raised coral atoll, standing today about 8m above sea level.

Aldabra itself consists of four islands, Picard, Polymnie, Malabar and Grande Terre, encircling a vast central lagoon that fills and empties via four channels twice daily, leaving 80% of the lagoon dry each low tide. Picard is where the Aldabra research station is located and where we are based.

We have dived in the main channel, between Picard and Polymnie, to film and photograph the abundant coral life there, but since our first fast pace drift dive in Pass Dubois, a smaller channel between Picard and Grande Terre, which swept us into the opening of the Atoll’s azure lagoon, we have synchronised our dives with slack tide. With approximately 60% of the lagoon’s tidal flow passing through main channel alone the flow can reach a rate of 6knots; it is a dark blue river in the ocean and not one in which I want to get caught diving on an outgoing tide as its current will see me joining the lemurs in Madagascar!

This UNESCO World Heritage Site, since 1982, was once a well-known location for large shark species, but with heavy fishing pressure, particularly from long liners, in the Western Indian ocean linked to the huge trade in shark fins we want to know if man has spoilt even this most remote of locations. Has the shark population, especially the large species such as tiger, oceanic-white-tips and great hammerhead sharks, here been decimated as it has in all our oceans? The deep ocean surrounding Aldabra makes it possible for us to look for pelagic (oceanic) species of sharks, but they have eluded our cameras. Even the majestic tiger shark, which should be here, has not unveiled its whereabouts. 

Thus far we have photographed and filmed an abundant population of reef and inshore sharks including, black tip reef, grey reef, sicklefin lemon and tawny nurse sharks, and I have been lucky enough to free dive with and photograph one of my favourite shark species, the silver tip. As their name suggests their fins, especially the pectoral fins, are splashed with a prominent silver sheen. Shy at first with me in the water she soon lost her inhibitions and became a very fast and inquisitive subject. They can reach up to 3 metres but we are only seeing small ones here of 1.2 metres in length, the fully-grown adults are probably in deeper water – if they have not all been fished out.

Spending so much time underwater in the protected reefs that encircle and penetrate into the heart of Aldabra it is refreshing to see that exuberant coral growth and profuse fish populations still exist here despite the rise in water temperatures that destroyed 40% of Adlabra’s corals. Co-incidentally, I am here in the year marked as the International Year of the Reef exactly ten years since this coral bleaching event. Reading a recent study of coral reef organisms, that covered everything from microbes to sharks, I can understand why the Aldabra reefs are so healthy. The answer is simple; they are teaming with reef sharks. Predators accounted for 85% of the total fish weight in the study’s pristine reef site, a complete reversal of life on reefs across the world today where most of the sharks have ended up dead on rows of baited hooks and where the reefs are depauperate of life.

Sharks are essential to coral reef health because they are the pinnacles of the food chain, and if they are removed from the ecosystem the whole ocean tilts off balance. Sharks have a very slow reproductive rate and do not recover well from exploitation. Over fishing sharks sets off a domino effect throughout the reef: fewer sharks leads to an increase in their prey, large carnivorous fish such as grouper, which in turn decrease the number of important plant-grazing herbivorous fish, such as parrotfish. Once this happens the reef is in danger of shifting from coral to algae domination and it is less able to withstand other human disturbances such as rises in water temperatures.

At the end of a long dive this morning photographing the coral gardens I was greeted by a huge yet weary lemon shark. Perhaps one day this regal predator will be given the respect it deserves as guardian of the reefs. Until then at least the inshore waters here are a welcome sanctuary.

Visit http://www.saveourseas.com to learn more about SOSF and the marine environment.