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It is well known to UAE residents that the seas surrounding the country are full of life, with a great variety of fish landing on our dinner tables every day.

It is, however, less well known that both the Arabian Gulf and the Gulf of Oman are home to several dozen of species of marine mammals. One of these, the seacow or dugong, featured already in an earlier issue of this magazine. This time we are taking a closer look at the whales and dolphins that live in our region.

One third of the 81 species of whales and dolphins, collectively called cetaceans, are thought to occur off the shores of the United Arab Emirates. They are divided into "mysticetes" - the baleen whales - and "odontocetes" or toothed whales and dolphins.

Dolphins or porpoises are more commonly known as they occur in larger numbers and are often curious and playful, allowing close-up observations.

In general, the deep waters on the edge of the continental shelf off the UAE's east coast harbour different species than the warm, sandy shallow waters of the Arabian Gulf. In the former habitat, one may find the mighty Sperm Whale (Physeter macrocephalus) that reaches 20 m in length, and the even larger Blue whale (Balaenoptera musculus) who used to grow to 30 meters in length (in the days before they were hunted intensively) as well as the largest of the dolphins, the 4 meter long Risso's dolphin (Grampus griseus).

In the Arabian Gulf habitat of shallow water channels between mudbanks and mangrove swamps lining the offshore islands, the rare Finless porpoise (Neophocaena phocaenoides) is most at ease, while the quite common but shy Indo-Pacific Humpback dolphin (Sousa chinensis) stays in shallow but open waters.


 

Much of what we know about the local species of cetaceans was based initially on observations made by members of the Natural History Group of Abu Dhabi in the late 1970's and early 1980's. Later, proper research was done by Robert Baldwin, who was provided with a grant from the Union National Bank to survey the UAE waters and coasts. New data are being added regularly by ENHG members as they make their exploratory trips along the coasts and to the islands of the UAE.

The marine mammals are an interesting group of animals because of in spite of their underwater existence they need air to breathe and consequently have to surface regularly to draw air. They do this via one or more blowholes on top of the head. The sound produced by the blow can, in the case of the large whales, be heard and seen from great distances. Having to breathe air makes a whale or dolphin vulnerable, as any caught in nets are drowned. The toll of drowned dolphins in the nets meant for tuna fish has been horrendous in the past. Nowadays many people boycott tuna products if they know the fish have been caught with purse-seine netting that traps the dolphins inside.

The animals are insulated from the cold water by a fat layer of blubber, by which they maintain their body temperature at around 38 C. The female gives birth to one live young that is born tail first. The newborn whale or dolphin must immediately rise to the surface for its first breath of air.

Toothed whales and dolphins have a remarkable sonar system, which allows some dolphins, for example, to distinguish similar objects over distances at which sight is ineffectual. They can also communicate with other dolphins and echolocate at the same time, even at targets that are both near and far, as well as at right angles from the main echolocation beam. No human sonar system can achieve anything like this. In order to process and analyse all this information, many dolphins have large brains, located in their bulbous skull.

Of the baleen whales six species are found here. Baleen whales do not have teeth, but filter sea water to obtain the small krill that constitutes their food. The "baleen" consists of hundreds of furry, comb-like plates that hang from their upper jaw. Each of the plates has many stiff hairs that form a sieve-like structure that filter small fish or crustaceans from the sea water. The largest is the Blue whale (Balaenoptera musculus) that can reach a length of over 25 meters and weighs more than 100 tonnes. The largest recorded female weighed 190 tonnes (equaling the mass of 90 elephants), making it the largest animal that ever lived on earth. Even a newborn calf is 7 meters long and weights 2500 kilos. It needs 190 liters of nutritious milk a day and gains 600 kg of weight every week. The adults eat up to 4000 kg of shrimp-like krill per day. They live solitary or in pairs, probably because they need large areas to feed in. They have been the target of relentless hunts by whalers. Over 1200 of these miraculous animals were killed by Russian whalers in the Gulf of Oman alone between 1963 and 1966.. (During this same period 849 Bryde's whales, 242 Humpback whales and 954 Sperm whales fell prey to factory whaling in Omani waters). Only around 5000 - 10.000 individuals of the Blue whale remain in the entire world.

The whaling industry, that has been much reduced in recent years by whaling bans, used to thrive in past centuries. Whales were hunted mainly for the oil made from the fatty layer beneath their outer skin. It was known as the "liquid gold" of the whaling industry. In earlier centuries it was used to light lamps and more recently it has been used in the manufacture of soap, lipstick, cooking fats, ice cream, machine lubricants and even the glycerine for explosives. The baleen plates, also called whalebone, were used for whip handles, shoe horns, fans and many other unlikely products such as whalebone corsets! Whale meat was never very popular in the West, but is a delicacy in Japan even now. Whale skin was used to make bootlaces, bicycle saddles, handbags and shoes. The blood was used in fertilizers and adhesives. Even the tendons were used in tennis rackets, while the connective tissue yielded gelatin for use in sweets and photographic film. A special product was ambergris, known as whale gold. It is formed in the lower intestines of some sperm whales and disgorged when whales vomit. It is often found floating in the sea or washed up on shore, but also when a whale is killed. Despite its unpleasant origin, it smells pleasantly. It used to be worth its weight in gold, as a medicine, an aphrodisiac and an ingredient in perfumes and cosmetics. The largest lump of ambergris ever found weighed 635 kg - a lump so large that one can hardly believe that it could have come out of a sperm whale.

The next largest baleen whale is the Fin whale (Balaenoptera physalus) that grows to up to 20 m in length. It is a fast-moving whale that can be recognized by a pattern of white pigment that runs from its underside along its right lower jaw into the mouth. It is both an open ocean dweller and a visitor of coastal waters and therefore found in the Arabian Gulf as well as off the east coast.

The Humpback whale (Megaptera novaeungliae) has been studied most in our region, specifically by the volunteer researchers of the Oman Whale and Dolphin Research Group (OWDRG). It has not been recorded from the Arabian Gulf, but occurs off the east coast.

The Humpback gets its name from the way in which it arches its back before diving. It has long slender white flippers, many fleshy knobs (tuberosities) on its head and tail flukes that are white on the underside. The tail is flipped up high when it dives, and the OWDRG scientists have learned to distinguish individual whales by the patterns on these tail flukes. So far 54 individuals have been recorded that feed in the autumn in the bay of Masirah and breed in February-March off the coast of Dhofar. This is unusual behaviour for a Humpback whale, as in other parts of the world Humpback whales migrate over long distances between their feeding and breeding grounds.

Male Humpback whales sing under the water, producing a complex series of low grunts, squeals, chirps and whistles, making up separate themes, which are sung in a specific order. These songs can last from a few minutes to as long as half an hour. I had the privilege of hearing part of a whale song that had been recorded by the scientists of the OWDRG - it was a haunting melody that moved me deeply. The function of these whale songs is not yet known exactly. They may form part of a sexual ritual or they may help to maintain social order.

Among the smaller whales are Bryde's whale (Balaenoptera edeni) the Sei whale (Balaenoptera borealis) and the Mink whale (Balaenoptera acutorostrata)

Bryde's (pronounced Broo-dess) whale has been recorded from both the Arabian Gulf and the Gulf of Oman. It is probably the most common whale off the east coast and breeds in this region. It is distinguished from the very similar Sei whale by having three parallel ridges on the top of the head to the blowhole. Minke whales are the most plentiful world-wide, but quite rare in this area. It is the smallest of the whales and can be identified (sometimes) by having a white band on its flippers. The Sei whale grows up to 20 m long and is easily confused with other whales of similar size. They are, however, rarely seen since they stay in deep waters.

The toothed whales are represented in our region by the Sperm whale (Physeter macrocephalus) that has been recorded only in the Gulf of Oman. It can reach a length of up to 20 m and can be distinguished by the forward direction of its blow and the humplike dorsal fin.

All the other odontocetes here are dolphins, including the mis-named Killer whales and False killer whales.

The Killer whale or Orca (Orcinus orca) is the largest of the dolphins and easily recognized by its striking black-and white coloration that includes an oval white patch above the eyes.

Orcas grow to 10 m in length and weigh in at 8 tonnes. They live and hunt in pods of up to 30 individuals. They male a great display of activity, spouting loudly, breaching and lobtailing as well as spyhopping - behaviour by which the animal raises its upper body vertically out of the water in order to observe its surroundings. The most easily distinguished feature of the orca, besides its colours, is its dorsal fin, a huge triangular fin that can reach almost 2 meters in height in adult males. Orcas hunt in packs and in different parts of the world they have developed different hunting techniques, most likely inspired by the type of prey available in those areas. In January 2001 orcas were reported to have chased 31 dolphins onto the shore in southern Oman. Of these beached dolphins 20 were rescued by local villagers, who towed them back into the sea. Of the 11 dead dolphins most were the common Bottle-nosed dolphins, but three were Rough-toothed dolphins (Steno bredanensis) which had not been recorded till that time. In spite of their fear-inspiring name, Killer whales have never yet been reported to attack and kill humans.

The False Killer whale (Pseudorca crassidens) has been recorded from both the Arabian Gulf and the Gulf of Oman. They live and hunt in pods of up to 30 individuals and are playful and gregarious. They often leap clear of the water, showing their all black body and blunt head, and ride the wake and bow waves of passing ships. They can approach to within touching distance and are obviously a favourite of whale-spotters.

Risso's dolphin is also a large dolphin, up to 4 m long, that lives in the Gulf of Oman. It is a deepwater species that spyhops but does not leap out of the water. It has a heavily scarred appearance, apparently from aggressive encounters with other pod members.

The dolphins are better known than the whales, because some species are often encountered by fishermen and people in sailboats or yachts. The most commonly encountered dolphin is the Bottle-nosed dolphin (Tursiops truncates). It is easily recognized by its short stubby beak and large forehead. It is inquisitive, friendly and playful and delights people with its displays of aerial acrobatics. I once watched such a display from a small boat off the Musandam coast and was amazed at the fact that these wild animals came close enough to the boat to be touched. To see them jump against the backdrop of the stark Musandam cliffs was awesome. Bottle-nosed dolphins occur both in the Arabian Gulf and in the Gulf of Oman and live in pods of up to 35 individuals.

An even more acrobatically gifted dolphin is the Spinner dolphin (Stenella lonirostris). As its species name denotes, it has a long slender beak. It is smaller (up to 2 m) and has a white belly and a grey flank band, and during its leaps it spins around its longitudinal axis and somersaults in spectacular displays. Spinners can occur both in the deep waters of the Arabian Gulf and the Gulf of Oman in pods of up to 300 individuals.

The Common Dolphin (Delphinus delphis) that is slightly larger than the Spinner, is easily recognized by its hourglass coloration on the flank. The fishermen call it 'abu salaama', the father of peace. It is mainly found in the Gulf of Oman where it can occur in pods of up to 100 individuals.

Of the same size is the Indo-Pacific Humpback dolphin (Sousa chinensis) that has a raised fleshy hump supporting the dorsal fin, which is curved backwards. It is a shy, uniformly grey animal that is locally called "dukhs" and occurs only in the Gulf of Oman.

The smallest of the dolphins is the Finless porpoise (Neophocaena phocaenoides), distinguished by the lack of a dorsal fin. Local fishermen call it "fa'ima". Until the 1990's it was known from the remains of only one specimen washed up in the early 1990's on the shores of Abu Dhabi, but in later years others have washed up in the northern emirates as well. Instead of a dorsal fin, it has a row of small tubercles on its back and it is said that this helps to provide a baby dolphin with a grip when it rides on its mother's back. This is the only dolphin to exhibit this kind of behaviour. As described above, this dolphin likes to come close inshore to hunt in the mangrove lined shallow sea-water channels of the offshore islands.

All of the whales and many of the dolphins are endangered animals. Threats to their existence include fishing with nets (especially dangerous for those species that prefer to live in shallow, onshore waters), pollution from oil, PCB's and general litter, noise pollution, and coastal development and human recreation. The UAE have started to protect this natural resource by introducing conservation measures and regulating fisheries activities as well as promoting and supporting detailed research.
 

 

   

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