PADI Manta Awareness speciality
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PADI Manta Awareness speciality by Stuart Gow www.Scuba-Diving-Fiji.com
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PADI Manta Awareness speciality
- 1. MANTA RAYS IN FIJI
- 3. RAYS OF THE WORLD HUGE VARIETY AND ABUNDANCE OF RAY SPECIES MAJORITY ARE BOTTOM DWELLERS WITH FLAT BROAD BODIES A FEW SPECIES TOOK TO THE OPEN WATER 45 Guitarfishes 260 Skates 70 Electric Rays 180 Stingrays
- 4. MANTA FAMILY TEN SPECIES IN THE MOBULIDAE SUB-FAMILY THE MANTA RAY & NINE MOBULA RAYS ALL FILTER FEEDERS WITH FORWARD FACING MOUTHS FIRST APPEARED ONLY 20 MYA Smooth-tail Mobula Ray Manta Ray Devil Mobula Ray
- 5. MANTA FACTS LARGEST MANTA; 6.8m (22ft) WIDE & WEIGHT 2,000kg PELAGIC VS RESIDENT Global Distribution TWO COLOUR MORPHS; CHEVRON AND BLACK A 6m Manta Ray Caught in 1933 off New Jersey, USA
- 6. MANTA FEEDING HUGE MOUTH FOR CATCHING PLANKTONIC FOOD PADDLE-LIKE CEPHALIC FINS UNFURL WHEN FEEDING Planktonic mysid shrimp CHAIN FEEDING & BARREL ROLLING
- 7. MANTA MATING The two claspers of a male manta ray Male and female mate at the surface Manta teeth The male bites hold of the females wing Mating Train
- 8. MANTA BIRTHING A heavily pregnant female visits a cleaning station Females give birth to usually just one (1.5m), fully independent pup after a pregnancy of about one year Near term unborn manta ray pup
- 9. MANTA PREDATORS MANTA RAYS HAVE FEW NATURAL PREDATORS Tiger Shark Orca or Killer Whale Stumpy probably lost the end of his pectoral fin to a Tiger Shark
- 10. CLEANING STATIONS A manta opens it’s mouth wide for the dentist Striped Remora or Shark- sucker Cleaner Wrasse Cleaning stations offer great close encounters for divers
- 11. THREATS TO MANTA RAYS Marine debris BYCATCH Tuna purse-seine net fisheries Gill nets Shark fin fishing
- 12. MANTA FISHERIES LOCAL SUBSISTANCE FISHERIES IN THE 1990’S LARGE SCALE COMMERCIAL FISHERIES BEGAN IN MEXICO & THE PHILIPINES NEW DEMAND FOR MANTA BRANCHIAL FILAMENTS IN CHINESE MEDICINE TRADE INDONESIAN FISHERIES STARTED IN 1998 TO SUPPLY DEMAND
- 13. MANTA FINNING IN THE MALDIVES EVEN THE MANTAS IN THE MALDIVES ARE NOT SAFE FROM FISHING THIS MANTA WAS FINNED BY FISHERMEN, IT’S PECTORAL FINS CUT OFF TO BE USED AS SHARK BAIT, WHILE THE REST OF ITS BODY WAS DISCARDED
- 14. GLOBAL PROTECTION MANTA RAYS ARE LISTED AS ‘NEAR THREATENED’ BY THE WORLD CONSERVATION UNION (IUCN) SOME COUNTRIES HAVE TAKEN STEPS TO PROTECT THEIR MANTA RAY POPULATIONS IN HAWAII MANTA RAYS ARE PROTECTED BY LAW AND IN THE MALDIVES ALL RAY EXPORTS ARE BANNED. IN THESE TWO COUNTRIES ALONE MANTA RAYS GENERATE TENS OF MILLIONS OF DOLLARS EACH YEAR THROUGH TOURISM
- 15. CODE OF CONDUCT DIVERS AND SNORKELLERS SHOULD ACT RESPONSIBLY WHEN INTERACTING WITH MANTA RAYS MANTA RAYS ARE NATURALLY CURIOUS AND SOCIAL ANIMALS WHICH WILL, IF UNMOLESTED, APPROACH DIVERS DON’T TOUCH OR ATTEMPT TO RIDE ON THE BACKS OF MANTA RAYS TRY NOT TO SWIM DIRECTLY ON TOP OF THE CLEANING STATION Cleaning Station
- 16. FIJI MANTA RAY PROJECT KADAVU IN FIJI IS ONE OF THE BEST PLACES IN THE WORLD TO SEE MANTA RAYS A LARGE POPULATION SIZE AND REGULAR SIGHTINGS OFFERS EXCELLENT OPPORTUNITIES FOR RESEARCH ALMOST NOTHING IS KNOWN ABOUT THEIR REPRODUCTIVE CYCLE, FEEDING HABITS OR MIGRATORY PATTERNS THE FIJI MANTA RAY PROJECT WAS ESTABLISHED BY MATAVA TO TRY AND ANSWER SOME OF THESE FUNDAMENTAL QUESTIONS
- 18. WE NEED YOUR HELP!!! ANYONE CAN SEND THE PROJECT IMAGES OR VIDEO THEY HAVE TAKEN OF MANTA RAYS IN FIJI ITS IMPORTANT TO INCLUDE THE LOCATION, DATE AND TIME OF DAY WHEN THE IMAGES WHERE TAKEN IDEALLY IMAGES WHICH CLEARLY SHOW THE MANTAS UNDERSIDE SPOT PATTERNS ARE BEST DIVER FILMS A HEAVILY PREGNANT FEMALE MANTA AT MANTA REEF IN KADAVU, FIJI
- 19. PADI Manta Awareness ITS IMPORTANT TO INCLUDE THE LOCATION, DATE AND TIME OF DAY WHEN THE IMAGES WHERE TAKEN DEVLOPED BY MATAVA SPECIFICALLY FOR MANTAS IN FIJI INVOLVES 2 DIVES PHOTOGRAPHING ID SHOTS UPLOADING TO MANTA.ORG
- 21. Manta Magic Everyone should get the chance to experience this!!
- 22. MANTA MAGIC IN FIJI!
Notas do Editor
- What are Rays?: Of the 29,000 species of fish in the world’s rivers, lakes and oceans only about 1,000 are cartilaginous fish, the rest are bony fishes. Elasmobranchs = ‘elasmo branch’, plated gills. As their name suggests, all of the sharks and rays have a skeleton mainly composed of tough cartilage, which makes them very flexible and much lighter than the bony fish. Cartilaginous fish have been around for 450 million years, with sharks first appearing in the fossil record 370mya and rays 160mya. In this time their basic body plan has remained unchanged. There are currently about 400 species of sharks in the world, although this figure is likely to rise as new deep sea species continue to be discovered. There are about 550 species of rays in the world’s rivers, lakes and oceans.
- Rays of the World: There is a huge variety and abundance of ray species around the world. The majority are bottom dwellers, whose broad flattened bodies are superbly adapted to this way of life. To prevent themselves from sucking sand and dirt into their mouths, rays have spiracles on the top of their heads which allow them to breath in fresh sea water. Skates are the dominant rays in the temperate oceans of the world where they occur in large numbers down to the continental shelf They feed on small fishes and crustaceans which they crush with strong jaws and flattened teeth. The Guitarfishes are a strange group of fish which look like a cross between a shark and a ray, and its actually thought that this is what the transitional species that evolved from shark-ray may have looked like. Indeed fossil guitarfish 163 million years old have been found which look remarkably like those found species living today. The electric or torpedo rays are poor swimmers and rely on there ability to generate electrical charges to overpower their prey. They do this from two fleshy lobes situated on either side of the body. The stingrays are a diverse group morphologically, containing the stingray, whiprays, cow-nose rays, eagle rays and off course the manta rays. They occur in a wide variety of ecosystems; from the tropical and temperate oceans, to freshwater rivers and lakes in the tropics. Some species can even be found thousands of miles up the Amazon river, long since evolving away from their marine roots. As the name suggests a number of these rays possess a sting at the base of their tail, this barbed spine is used in defense and can inflict serious injuries on a predator or unfortunate wader.
- Manta Ray Family (Mobulidae): There are ten extant species which belong to the Mobulidae family and two genus within the family. There are nine Devil or Mobula rays and the Manta Ray ( Manta birostris ). All are filter feeders with huge mouths at the front of their heads. They can be found throughout the worlds temperate and tropical oceans. The first Mobulid appeared in the fossil record only 20 million years ago, making them some of the most recently evolved sharks and rays. Mobulas differ from the Manta in a number of ways; all are a lot smaller, with even the largest reaching only 5m on rare occasions and the majority reaching only a few metres. Mobulas still poses a spine at the base of their tail, manta do not. The cephalic fins of Mobulas only extend as flaps down from their heads, where as the manta rays cephalic fins unfurl to a much greater degree forming large paddle-like fins in front of the mouth. Mobula rays are also a lot shyer than manta rays and are much harder to observe underwater by divers. At least two species of Mobula rays occur in the Maldives as well as the Manta ray; the Smooth-tail Mobula ( M.thurstoni ) and the Pygmy Mobula ( M.eregoodootenkee).
- Manta Ray Facts: Mantas are a pelagic species, spending all of their time feeding on plankton in the water column. Manta rays can be found throughout the worlds tropical and semi tropical oceans, common in shelf waters where deep upwellings bring plankton rich currents to the surface. Manta rays can reach a maximum width of 6.8m (22ft), and weight 2,000kg (4,400lb) although a more common size is 4m. This makes them by far the largest of all the rays. Manta rays are born with very long tails, but these are often bitten shorter by predators, such as sharks, as the manta ages. Unlike other closely related species manta rays lack any defensive spines at the base of their tail, and rely on their speed and size to elude predation. Manta rays occur in two colour morphs; the first is the black morph, where the manta is largely black on both its dorsal and ventral surface, with some small areas of white spots and patches. The second morph is the chevron; this is by far the more common of the two morphs, where the manta has a black and white chevron patterned dorsal surface with a white ventral surface. This ventral surface is often covered in black spots and patches, creating a unique pattern on each manta ray which can therefore be used for identification. Although all manta ray populations around the world belong to the same genetic species, it appears that there is segregation both geographically and behaviourally. Some populations, like the Maldives, appear to stay in shallow water close to the reef, others have a more pelagic lifestyle travelling huge distances across the oceans. These pelagic mantas also seem to grow larger than the reef populations (which average 3-4m) growing to over 6 metres.
- Manta Feeding: Manta rays feed on zooplankton like mysid shrimps and copepods. They filter out the plankton using their gills like sieves, while cephalic fins on their heads unfurl to channel the food into their mouths. When they are not feeding these fins curl up in front of the mouth, making the rays look like they have horns, hence the name devil rays. They have a huge mouth, like their close relative the whale shark, which is situated at the front of their head. They can often be found in the Maldives feeding at the surface in large aggregations, its thought that by working together they can cause eddies with their wings concentrating the plankton.
- Manta Mating: Very little is known about the reproductive lifecycle of manta rays, as yet nobody has documented the birth of one, and only a few people have been lucky enough to witness matings. During the mating season the larger female manta rays test the suitability of potential mates by leading them on a chase, the males line up behind the female all vying for position until the closest male will eventually grasp one of the female’s fin-tips in his mouth. Both manta’s rise up towards the surface and mate belly to belly while falling downwards towards the reef. All sharks and rays have internal fertilization; males have two modified pelvic fins (known as claspers) and they insert one inside the female during mating to fertilize her. Manta rays only have teeth on their lower jaw and the males use them for gripping hold of the females pectoral fin during mating.
- Manta Birthing: It has also been said that female mantas leap clear of the water while giving birth. After mating it’s not known how long the female mantas are pregnant for, but it’s likely to be about a year. During this time usually just a single pup is nourished by milky secretions from the lining of the mother’s uterus, until it is born at a size of about 1metre (3ft) and ready to fend for itself. After being born the manta pup is completely independent from its mother, although there is anecdotal observational evidence to suggest otherwise. Manta rays often attract unwanted hitch-hikers, like remora fish. These fish use modified dorsal fins to suck onto the body of their chauffeurs, leaving the mantas to feed, but always returning to the safety of their host if danger threatens. There are two species of Remora fish which are commonly seen in the Maldives; the striped remora and brown remora.
- Manta Predators: Their large size means that manta rays have few natural predators, large sharks (e.g. Tiger and Bull sharks) and possibly Orcas (Killer whales) pose the greatest natural threat. However, a mantas flattened body also affords them a lot of protection by making it very difficult for a predator to get its teeth into the vital organs, often they escape with just a bite on the wing. While these injuries are severe, manta rays appear to have a remarkable ability to heal and it’s common to see individuals in the Maldives with old shark bites on the pectoral wings, or even whole sections of a wing missing. ‘ Stumpy’ is a male manta who has lost the end of his right pectoral fin to a shark attack, probably a tiger shark. He appears to be none the worse for his scar.
- Cleaning Stations: Manta rays often visit specific locations on a reef to have their bodies cleaned of parasites and dead tissue by small cleaner fish. These fish are commonly wrasses, although many other fish groups; such as angelfish, butterflyfish and gobies are also known to partake in cleaning. This relationship is mutually beneficial to both the manta ray, which would otherwise be unable to rid themselves of harmful parasites, and the cleaner fish, which get an easy meal. It’s also good for divers, as these cleaning stations provide the ideal location for getting excellent, close up views of these amazing animals as they glide within inches of the reef and the divers. Manta rays are naturally very inquisitive animals and will frequently approach divers; this level of curiosity and voluntary human interaction is very rare in most wild animals (especially marine animals) and adds weight to the theory that these are relatively intelligent and highly social animals.
- Threats to Manta Rays: Indirectly manta and Mobula rays often fall victim as unintentional bycatch in a number of other fisheries. Tuna purse-seine nets, drift nets and long lines, used for shark fin fishing frequently catch these rays which then quickly die as they need to keep swimming in order to ‘breathe’. In South Africa and other parts of the world where shark nets are used to protect the beaches, these rays and many other marine animals (such as dolphins, whales and turtles) are indiscriminately entangled and killed in large numbers each year to protect humans. All of the above manmade threats are especially difficult for manta ray populations to recover from due to their life cycle. Slow growth and maturity rates, long gestation periods, infrequent birthings and small litter sizes mean that this species is particularly vulnerable to exploitation. Where large scale fisheries have occurred it will take many of our generations before these populations recover, if ever.
- Manta Fisheries: For generations, where manta rays and their smaller relatives, the Mobula rays, exist around the world people have fished them for their oily livers, flesh and their tough abrasive skin. This type of local subsistence fishing has always been sustainable, with the fisherman taking a very small percentage of these rays’ populations. However in the 1990’s large scale commercial fisheries began to appear, targeting these rays for their fins, branchial filaments and even just as bait, having a devastating effect on the local populations. In Mexico and the Philippines populations have been decimated, with only a handful of manta sightings now reported each year in the fished areas, where a few decades ago their numbers were plentiful. In 1998, a few coastal islands in Indonesia switched from a local subsistence manta fishery to a new type of large scale commercial fishing to supply the new demand for dried manta branchial gill filaments, which are ground into powder and sold into the Asian medicine market. Before 1998 it was estimated that the local fishermen in these waters caught between 300-400 mantas per year in total. In 2002 the World Wildlife Fund (WWF) sponsored a survey to assess the impact of these commercial branchial fisheries; they reported a huge increase in the catch numbers of up to 2,400 for that year. Already in just a few years it appears that the local population has been decimated with local fishermen having to move further to find mantas. Target fisheries for these species also currently exist in several other countries, including Mozambique, Madagascar, India, Sri Lanka, Brazil, and Tanzania.
- Manta Fisheries: For generations, where manta rays and their smaller relatives, the Mobula rays, exist around the world people have fished them for their oily livers, flesh and their tough abrasive skin. This type of local subsistence fishing has always been sustainable, with the fisherman taking a very small percentage of these rays’ populations. However in the 1990’s large scale commercial fisheries began to appear, targeting these rays for their fins, branchial filaments and even just as bait, having a devastating effect on the local populations. In Mexico and the Philippines populations have been decimated, with only a handful of manta sightings now reported each year in the fished areas, where a few decades ago their numbers were plentiful. In 1998, a few coastal islands in Indonesia switched from a local subsistence manta fishery to a new type of large scale commercial fishing to supply the new demand for dried manta branchial gill filaments, which are ground into powder and sold into the Asian medicine market. Before 1998 it was estimated that the local fishermen in these waters caught between 300-400 mantas per year in total. In 2002 the World Wildlife Fund (WWF) sponsored a survey to assess the impact of these commercial branchial fisheries; they reported a huge increase in the catch numbers of up to 2,400 for that year. Already in just a few years it appears that the local population has been decimated with local fishermen having to move further to find mantas. Target fisheries for these species also currently exist in several other countries, including Mozambique, Madagascar, India, Sri Lanka, Brazil, and Tanzania.
- Global Protection: Manta rays are currently listed as “Near Threatened” by the World Conservation Union (IUCN). It’s known that several populations around the world are severely depleted, but not enough scientific work has been carried out to properly assess this species as a whole. Almost nothing is known about their population ecology, use of critical habitat, movements or reproduction, all of which are important if we are to accurately asses the state of the species. Some countries however have taken steps to enforce their own national protection for manta rays; the Maldives has a large population of manta rays which have complete protection and a thriving dive tourism industry which they help to support. The income which is generated from this tourism industry in the Maldives alone is calculated to be in the Millions of dollars annually, bringing much more money to the country than any manta fisheries could.
- Code of Conduct: Divers and snorkellers should ensure that they interact responsibly when encountering manta rays. They are curious and social animals who will often approach you, this should always be on their terms and chasing or attempting to touch or ride a manta will frequently result in them being frightened off. One the best places to observe them are at cleaning stations, where the mantas make regular visits to have parasites and dead skin removed from there bodies by small cleaner fish. While these locations offer excellent close encounters, it’s important that divers never swim directly onto the cleaning station or inhibit the path of the mantas.
- Maldivian Manta Ray Project: The Maldives is one of the best places in the world to dive or snorkel with manta rays, the population density here appears to be one of the highest anywhere throughout their range. Despite their relative abundance here almost nothing is known about their life cycle, feeding habits, or migratory patterns. The Maldivian Manta Ray Project (MMRP) was established to try and find answers to some of these fundamental questions.
- Project Research: All manta rays have a unique pattern of spots and markings on the underside of their body making it easy to identify individuals. Combining this pattern with tail length, sex and pre-existing scars helps to further confirm the mantas identity and enables us to build a photographic database of individuals. From this database, which includes all sighting history for individuals and its location, we are able to begin to build an understanding of seasonal migrations, localised daily movements, population size and cleaning and feeding behaviour. Updating and adding to this database is an ongoing task with new individuals being sighted on a regular basis, a clear photograph of the mantas underside is sufficient to confirm an existing or new identity and this is easily achieved when mantas congregate at cleaning stations. We welcome any photographs taken by divers who would like to contribute to the growth of our database.
- Project Research: All manta rays have a unique pattern of spots and markings on the underside of their body making it easy to identify individuals. Combining this pattern with tail length, sex and pre-existing scars helps to further confirm the mantas identity and enables us to build a photographic database of individuals. From this database, which includes all sighting history for individuals and its location, we are able to begin to build an understanding of seasonal migrations, localised daily movements, population size and cleaning and feeding behaviour. Updating and adding to this database is an ongoing task with new individuals being sighted on a regular basis, a clear photograph of the mantas underside is sufficient to confirm an existing or new identity and this is easily achieved when mantas congregate at cleaning stations. We welcome any photographs taken by divers who would like to contribute to the growth of our database.
- Project Research: All manta rays have a unique pattern of spots and markings on the underside of their body making it easy to identify individuals. Combining this pattern with tail length, sex and pre-existing scars helps to further confirm the mantas identity and enables us to build a photographic database of individuals. From this database, which includes all sighting history for individuals and its location, we are able to begin to build an understanding of seasonal migrations, localised daily movements, population size and cleaning and feeding behaviour. Updating and adding to this database is an ongoing task with new individuals being sighted on a regular basis, a clear photograph of the mantas underside is sufficient to confirm an existing or new identity and this is easily achieved when mantas congregate at cleaning stations. We welcome any photographs taken by divers who would like to contribute to the growth of our database.