Bulletin 1 - March 1977: Sea Cows



Sea Cows

A summary of the talk on the Order Sirenia presented by Professor Colin Bertram of St. John's College, Cambridge to the ENHG on 15th November 1986.

The order Sirenia is represented by two forms, the Dugong and the Manatee. These mammals suckle their young in a human manner while holding their single offspring to their breast. Their need to rise to the surface of the water to breathe while clasping their young may have given rise to the early mariners' stories of mermaids who nursed their progeny in a remarkably human manner.

The dugong is found in the warm shallow waters around Abu Dhabi and Bahrain, but covers a much wider area, from Aqaba in the Red Sea to the Solomon Islands in the Pacific Ocean, and especially in the waters of northern Australia. It is a very shy seal-like creature, without back limbs and growing to a length of 10 feet. Adult males may weigh up to 375 lbs; the females are usually smaller. Entirely herbivorous, it feeds on the higher green plants of the sea. Because it is a wandering, entirely marine animal that never comes on shore and is rarely seen, little is known of its life history.

The skin is very tough and the male has tusks, which protrude 2 -- 3 inches from the upper jaw. The female tusks are much narrower and remain in the upper jaw, never emerging. When the tusks are cut longitudinally they reveal lines from which the age of the animal can be approximated. They may live for 30 years or even more. The bones are much heavier than those of other animals and this may help them to remain submerged when they are grazing on the sea bottom.

When archaeologists opened up the mounds of Umm an Nar dating from 2700 BC, many dugong bones were found. They were probably harpooned as they browsed on sea grasses, gently going up and down with the tide.

The populations of dugongs the world over have been greatly reduced and there are now large empty areas of eel and other sea grasses in the shallow waters of the tropics. As no other large mammals graze on these grasses, there is surely a niche that can be re-occupied by the dugong. There is a great opportunity for the dugong to be protected and preserved in the waters of the Emirates, so that they may return to their former numbers once more. It would be a great pity to let such an interesting and useful animal become extinct.

The manatee lives mainly on the eastern coast of tropical south and central America, and also west Africa. It lives in both the sea and in estuaries and rivers. Attempts are being made to turn the manatee into a new domestic animal, and Professor Bertram has estimated that, from 10 breeding females now, there could be a breeding herd of maybe 1,000 females in 50 years time. Seven manatees have been known to keep 8.5-kilometres of fairly large canal clear of aquatic weeds in Surinam for 20 years.

Any reports or sightings of dugongs, particularly from the air, will be welcomed by the Group. Details of the landing of dead specimens would also be useful. If the carcass is whole, as many measurements as possible should be made i.e. nose to tail length, girth measurements at head, middle and tail, and so on. If the head can be retained, this will reveal a great amount of information, and it would be forwarded to Professor Bertram for study. The local name of the dugong is "bagar al bahr".

For recorder

  1. The meat of a dugong was on sale in the fish market at Abu Dhabi on 14th November 1976.
  2. It is reported that 60-70 dugong are brought into Abu Dhabi market annually.
  3. Note record by Tony Harris in this issue.

 


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