Manta Rays and Mobulas - the Gentle Giants of the Ocean Under Threat from Illegal Fishing
SEIFERT.GoldenManta C opt3

Killing the golden manta

Rest is the one activity unavailable to mobulids: the manta rays and their close relatives, the mobula rays. Unlike the other 500 or so species of benthic layabouts in the ray and skate family – the stingrays, sawfishes and guitarfishes – for mobulids, lying upon the bottom, blending in with the environment or conserving energy is not an option. From the moment they are born – released fully conscious, free-swimming and autonomous from their mother’s uterus – to the moment they cease to be alive – three to four decades later, should they live a natural life span – all their days and nights they roam their respective territories in tropical and subtropical seas, constantly, ceaselessly on the move. 

Mobulids must swim in order to breathe, they must swim to find food and, as ramjet filter-feeding specialists, they must swim to capture and engulf the small fish and microscopic varieties of plankton they prey upon. They must swim to find a mate (and to copulate), they must swim to avail themselves of parasite removal services by small fish at cleaning stations, and they must swim to evade their few would-be predators (transient orcas and a handful of large shark species) that do, on rare occasion, kill a manta. 

Mobulids can swim only forwards, they have no means to reverse course. Although they can ascend or descend, angle left or right, it is always with, and as a result of, forward propulsion achieved by undulations of their pectoral fins in the same manner that a bird achieves flight via flapping its wings. Mobulids are oftentimes observed to breach from under the sea, high into the air, for single or multiple leaps. But because they cannot swim backwards, and because of their particular anatomy – a broad, thick disc of a body supporting a pair of wide, triangular-shaped, flexible pectoral fin ‘wings’ and a protuberant head horned by a pair of cephalic lobe fins, - mobulids are prone to entanglements in man-made apparatuses, such as fishing and mooring lines, gill nets and purse seine nets. Mobulids can swim but they can’t hide.


Until recently, it was assumed there was only one monotypic species of manta ray found worldwide. Now there are currently two recognized species. The larger and more pelagic-migratory oceanic manta ray (Manta birostris), reaching a maximum of seven metres and in excess of 1,400 kilos, and the smaller reef manta ray (Manta alfredi), with an up to 5.5m but more commonly 3m ‘wingspan’ which is the more commonly encountered species and remains largely resident within a predictable range around its oceanic island reef territories. 

In 2012, the world is likely to learn of a third species of manta. So far the species is officially unnamed but likely to be called the Atlantic manta ray or Caribbean manta ray and classified as Manta giorna. It is found only in the Atlantic Ocean, primarily in the Bahamas, the Gulf of Mexico and the Caribbean Sea south to Venezuela. The potential ‘new’ manta has characteristics of both other species of manta, possibly making it the rare case of an interspecific hybrid that has become reproductively successful and abundant and has developed into its own species – hybrids in nature are usually sterile.

In the family Mobulidae, the mantas are joined by close relatives, the mobulas, or devil rays. The mobulas are comprised of some nine species, found circumglobally, in tropical, subtropical and temperate waters. Although similar in body shape to mantas and frequently mistakenly identified as such, mobulas can easily be discerned from mantas by the anatomical disparities, specifically in the contrast between where the mouth is situated and how the cephalic lobes (cephalic fins) are oriented. Differences in coloration and colour patterns are also quite distinct, though there is enough variation among individuals to make coloration, like size, not a diagnostic factor.

With manta rays the mouth is large and wide and it terminates with the leading edge of its pectoral fins and body, situated between its cephalic lobes on the chondrocranium; mobulas have a smaller mouth that is underslung beneath and behind the chondrocranium.

The cephalic lobes of mobulas are much more rigid, more horn-like in appearance than a manta’s supple, flexible cephalic lobes, which by mood or by necessity can unfurl into paddle shapes or retract into tightly wound horn-shaped projections. Cephalic lobes are modified fins that serve to funnel water as well as to concentrate prey suspended within the water into the mouth, passing water over the gills to achieve respiration and trapping the prey in branchial filter plates prior to swallowing the prey.

Some mobula species are geographically specific, others are found worldwide, and the various species range in size from the one-metre-at-maturity pygmy devil ray (Mobula munkiana) of the Eastern Pacific Ocean to the 5m-plus giant devil ray (Mobula mobular), found primarily in the Mediterranean Sea. Overall, mobulas are less well studied than manta rays, due to their peripatetic existence in offshore, deep-ocean environments, and the relative infrequency with which they are encountered alive in their natural environment. As with manta rays, mobula sightings are most frequently encountered near seamounts, coral reef cleaning stations, found in large feeding aggregations or poorly-understood migration events. Although less well known than their manta relatives, it is believed that the worldwide mobula population probably exceeds the worldwide population of manta rays by an exponential amount.

Divers and snorkellers all over the world actively seek out encounters with manta rays, in destinations such as Hawaii, the Maldives and Indonesia. For those fortunate enough to encounter manta rays in their natural setting, on a reef – being cleaned of irritating parasites by a flotilla of tiny wrasses at a coral bommie cleaning station, or simply passing by off the reef’s edge out in the blue – or while they feed upon plankton just below the sea’s surface, the impression given to people by manta rays is almost universal: they are perceived to be majestic animals, graceful, benign, non-threatening, aware, sometimes curious, with the sparkle of intelligence in their unblinking wide eyes. Indeed, mantas and mobulas are among the most intelligent fish in the sea, with the highest brain-to-body mass of any member of the ray family. 

The most popular liveaboard dive boats specifically tailor their cruise itineraries to locations where manta rays have a high likelihood of being seen: Manta Alley in Southern Komodo Island; The Boiler at San Benedicto Island in Mexico’s Revillagigedos Islands; Lankan Manta Point, Dhonkalo, Nelivaru and Hanifaru in the Maldives; Rangiroa, Manihi and Fakarava atolls in French Polynesia; Magic Mountain, Manta Ridge and Manta Sandy in Raja Ampat, Indonesia; and Gonubalabala Island in Papua New Guinea, to name just a few. 

Land-based operations exploit known local manta haunts, getting as many paying tourists to the mantas as they have boats to carry them. Indeed, in places such as the tiny Micronesian island nation of Yap, the allure of diving with manta rays is the attraction that sells the package, bringing millions of dollars into the local economy and the dive operations. Manta ray dives on the Ningaloo Reef in Western Australia have overtaken whale sharks as the big-draw moneymaker for local operators and Bali’s Manta Point at Nusa Penida brings in
US$3 million to the dive centres.

A reliable dive site that virtually guarantees the participant an in-water experience with a large, benign marine creature – be it a whale shark, manatee, whale or manta ray – is the dream of every tour operator who hopes to make a living in the dive or snorkelling industry. Tourists from all walks of life, of all ages, and ethnicities, willingly pay relatively large sums of money for a nature experience and an outing with a large aquatic animal (and one that isn’t too frightening). It is the most tangible, clear-cut example of the allegorical story from Aesop’s Fables of the goose that laid the golden eggs. In a very real sense, a manta dive is that golden egg. As long as the manta swims in a place that is known, and within reach via a reasonable boat ride, people will come willingly and enthusiastically and they will pay for the privilege. It is a natural resource that is completely renewable and wholly sustainable, as long as human behaviour is tempered in such a fashion to not scare away the mantas. 

There is no finer example of the financial value of manta encounters than the success of Kona, Hawaii and its world-famous manta ray night dive and night snorkelling programme. In Hawaii, the reef manta rays (Manta alfredi) have been studied for more than a decade and each manta within that resident population has been identified by its own individual characteristic markings and colorations. The population is known to number 146 individuals. 

Those manta rays gather at a few known shallow-water sites at night to feed upon plankton attracted by high-intensity lights shone from dive boats at anchor and from the divers’ torches placed en masse on the bottom at 16m depth. The mantas sense food and swim determinedly to funnel and engulf the swarming plankton clouds illuminated by and concentrated in the bright shafts of electric lights. They perform barrel rolls as they feed, inches away from the divers and snorkellers. It is a man-made phenomenon that takes advantage of plankton’s tendency to mass drawn by lights at night and the mantas’ exuberant feeding behaviour upon finding an abundance of food. Manta numbers vary by night, with half a dozen mantas participating some nights; or other nights there can be as many as 30 mantas in a plankton-feeding hullabaloo. 

Currently, the dive and snorkelling operators of Kona in Hawaii earn a combined US$3.4 million per year directly from the manta encounters. (There are roughly 20 operators offering manta ray dives/snorkels and currently divers pay US$145 per person; snorkellers US$95).

Each of the identified 146 individuals currently generates US$23,288 per year and thus, as mantas are believed to have a lifespan of 40-plus years, each of those mantas will, over the course of their lifetime, generate one million dollars to the Kona operators in direct revenue from the manta encounter excursions alone. This amount does not reflect the mantas’ additional value to the local economy, with income from airfares, hotels, rental cars, taxes, restaurants, employment, and much more.

From a financial perspective, the manta is not a just another fish in Hawaiian waters - but an economic benefactor that can legitimately, and accurately, be described as ‘The Million-Dollar Manta’. As long as there are mantas, operators can run their boats, pay their staff, cover their overheads and collect their profits. But if the mantas go away, all the operators will have left to sell is ‘coral gardens’ and vacant seawater – and that is not much of a business plan.



Photographs by Shawn Heinrichs


One segment of the dried seafood business is devoted to fulfilling gourmet ingredients for Chinese gastronomy, such as sea cucumber for sauces and shark fins for soup; the other segment is what is known as the Traditional Chinese Medicine market, where dried seafood joins other desiccated plunder of the natural world: rhino horn, tiger penis, seahorse exoskeletons and the like. Practitioners of Traditional Chinese Medicine assert that these ingredients are therapeutic and have legitimate curative use; the 2,000-year history of Traditional Chinese Medicine cannot simply be dismissed due to Western prejudices. Science is ever-evolving and although some may turn their noses up at animal ingredients used in medicine, no one can say with any certainty why some things appear to work for some people and some do not. (Before you scoff: just ask yourself why chicken soup is so often prescribed to combat a common cold in the Western world?)

What can be said is that if an ingredient or compound has not been recorded in the meticulously detailed, long written history of Traditional Chinese Medicine, then it is not a studied and recognized remedy. The use of manta ray gill rakers has no recorded history as an ingredient in TCM in any of the literature. It is only being recommended now and in the past ten years by a new generation of entrepreneurs playing upon the fears and superstitions of an unsophisticated but suddenly affluent clientele. Manta gill rakers are sold as a miraculous ingredient of a cleansing tonic or soup. The vendor spins his or her tale of the incredible properties of the gills, using crackpot reasoning about filtering seawater. Surely, they claim, there is a benefit from this filtration – especially when considering the terrible air pollution over China’s cities. Or they bolster the immune system; or perhaps act as an anti-inflammatory; or as a cure for cancer; or the chicken pox or, or, or… fill in the blank. 

The term ‘snake oil salesman’ has a long history associated with charlatans selling pseudo-science to a gullible public. Today, the snake oil salesman has been supplanted by the Chinese seller of manta ray gill rakers. Sellers of manta ray gill rakers do not even necessarily label them as such for the consumer. Often, the translation is ‘Peng Yu Sai’ or ‘fish gills’. 

The epicentre of this manta ray gill raker industry is located in one location: Guangzhou, China. This is where 99 per cent of the manta ray gill rakers from all around the world are brought to be sold at their highest wholesale market price. This is the manta ray gill raker distribution city. And the price?

The median sale price in Guangzhou is roughly US$250 a kilo for large gill rakers, and US$133 a kilo for small ones. Based on the average estimate of around 60,000kg of gill rakers traded annually, their total retail market is projected to be worth US$11 million per year. For this relatively small-short term gain, tens of thousands of manta rays and mobulas are killed every year, have been killed every year for the past decade, and many thousands more will be killed until there simply are no more manta and mobula rays left.

And all for a bogus potion with no legitimate place in medicine, and the quick but fleeting dollar that accompanies it. This commercial fishery specifically targeting manta and mobula rays has rapidly come into deadly existence, flourished and expanded with alarming efficiency. As you read this feature, scores of persistent, determined fishermen in small wooden boats are plying the tropical waters of the Indian Ocean off India and Sri Lanka, where fishermen land more than 79,000 mobulas per year; the hunt never ends in the Indo-Pacific Oceans off Indonesia and the Philippines, where tens of thousands more mantas and mobulas will find their way to fish markets and eventually their gill rakers will make their way to China – and in the Pacific waters off China and Taiwan, the numbers of mantas and mobulas killed will go unrecorded and unheralded, as if it never happened. 

The scenario is stark and brutal: first, the fishermen must find the animals, then the manta rays and mobulas will be pursued and caught – entangled and drowned with gillnets – or harpooned with hand-forged iron spears and then hacked to death with machetes. It does not need to happen; it must not be condoned. 

The monetary value of that dead manta ray or mobula in a fish market brings a one-time-only value of US$40 to US$500, depending on the size of the animal and the size/weight of its gill rakers. That same animal, swimming off the coast of Hawaii or Bali or the Maldives provides a livelihood worth millions of dollars for local people, as well as a legacy for future generations.

It is not necessary to have a degree in economics to understand that a live manta is worth more to the world, to people and to mantas themselves, than a dead manta. The world needs to implore the Chinese government to ban this wasteful industry. Remove the incentive to kill manta and mobula rays and the fishermen will find other opportunities. 




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