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Bottlenose dolphins vary tremendously in color and shape between individuals, and according to geographical region.
They also show a more striking range in size than any other dolphin species.
These are the largest bottlenose dolphins sighted on the voyage to date.
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Photo : Chris Johnson |
May 17, 2004
Dolphins and Boobies in the Desert Sea
Real Audio Report
28k
Log Transcript
Last week, the crew sailed into Massawa, a small town on the African coast of the Red Sea and the main port of Eritrea. Squeezed between the sprawling desert masses of Sudan and Ethiopia, Eritrea is arguably one of the hottest, most inhospitable regions on earth, while the buildings in Massawa are battle-scarred after a 30-year fight for independence from Ethiopia - the longest civil war in African history.
A few days gave us sufficient time to refuel, provision, clean Odyssey and travel inland for a day to the capitol city of Asmara. Once considered the 'Pearl of the Red Sea', Massawa was a friendly and engaging respite after three weeks at sea.
The Odyssey crew is currently sailing north up the Red Sea - a body of water early traders and explorers making their way into the Indian Ocean, called the 'Route of Spices'. Although named after the red pigmentation of Oscillatoria - a genus of blue-green algae, the Red Sea appears anything but red, and ranges from deep green offshore to light aqua along the coast. Yemen, Saudi Arabia, Jordon and Isreal border this 1,900-kilometer long, 300-kilometer wide sea to the east, while Djibouti, Eritrea, Sudan and Egypt lie to the west. It is a relatively shallow sea with an average depth of only 490 meters, which explains why the subject of our research, the deep diving sperm whale is not known to inhabit this region.
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Two species of bottlenose dolphins are currently recognized,
though it is likely there are more. The common bottlenose dolphin (Tursiops truncatus) and the Indian Ocean bottlenose dolphin (Tursiops aduncus) We are curious to know if we saw one or both species of Tursiops here in the Red Sea.
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Photo : Chris Johnson |
The semi-enclosed Red Sea supports an assortment of endemic marine life. It is perhaps most famous for its spectacular coral reefs, but supports a diverse range of habitats. Mangrove forests grow along the coastline, scattered islands support dense seabird colonies and nesting sea turtles, while dugongs graze on sea grass beds inshore. No large cetaceans are known to occur here. However, there is the possibility of at least one species of small endemic dolphin - a reflection of the regions isolation and narrow geographical range.
Along the southern coastal area of the Red Sea, brown boobies joined us by the dozen. Together with the white-eyed gull, this species nests on uninhabited offshore islands. From dawn to dusk they flew in our wake, circled the boat and glided overhead, flying as close to the crew on the bow as only the curious booby dares. Gliding to windward, they settled on the water in rafts (groups), floating gracefully and bobbing up and down over the waves. As soon as we left them a few hundred meters astern, the group rose like a great brown cloud and overtook us before skidding back down to the sea surface with webbed feet extended. This pattern was repeated throughout the daylight hours and the crew never tired of their presence. As we continued north, the boobies became conspicuously absent, although dolphins joined us in abundance.
Spinner dolphins (Stenella longirostris) and Pan-tropical spotted dolphins (Stenella attenuatta) usually dropped by more than once a day, and often together. However, the species that is most intriguing to the crew is the bottlenose dolphin (Tursiops). These are the largest bottlenose dolphins sighted on the voyage to date, dwarfing the spinner and spotted dolphins when riding together ahead of our bow. While the latter two species form schools numbering in the hundreds, we scarcely see more than ten bottlenose dolphins together at one time. Their superior size seems to give them right of way and they take over prime position ahead of the bow,
the smaller species relegated to the periphery. While the movements of the smaller species are fast and furious, the robust bottlenose dolphins rise and fall with slow, effortless grace, their tails barely moving. This species appears intensely curious, rolling on their sides and leaping clear of the water. Sometimes they were practically eye-to-eye with the crew on the bowsprit.
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Brown boobies circle Odyssey flying inches from the crew on the bow. Boobies are notorious for being curious and often try to land onboard.
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Photo : Chris Johnson |
Bottlenose dolphins are arguably the most easily recognized and best known of all cetaceans, featuring prominently in modern aquaria, scientific and popular literature, as well as in ancient Greek and Roman mythology. The name Tursiops is literally translated as 'dolphin-like', derived from the Latin "Tursio" (dolphin) and the Greek suffix "-ops" (appearance).
Bottlenose dolphins vary tremendously in color and shape between individuals, and according to geographical region. They also show a more striking size range than any other dolphin species. Physically mature adults may vary in length from under 2 meters to almost 4 meters, with a weight range of 150 to 650 kilograms.
Two species of bottlenose dolphins are currently recognized, though it is likely there are more. The common bottlenose dolphin (Tursiops truncatus) is widely distributed in temperate and tropical waters worldwide, including coastal and offshore waters, and semi-enclosed seas. The Indian Ocean bottlenose dolphin (Tursiops aduncus) appears to be limited to the coastal Indian Ocean and Western Pacific. We are curious to know if we saw one or both species of Tursiops here in the Red Sea. Our Tursiops sightings and photographs of what appear to be exceptionally small spinner dolphins indicate the need for dedicated research of small cetaceans in the Red Sea, a remote and poorly understood extension of the Indian Ocean.
Last night at twenty-three and one half degrees north latitude, we crossed the Tropic of Cancer - an invisible line representing the maximum declination of the sun in the sky during the northern hemisphere summer, it also coincidentally signifies the end of the tropics. On the same night, we watched the Southern Cross slowly recede over a midnight swell. For over four years and tens of thousands of miles, this constellation was our constant and reliable companion. It was strange and somewhat unnerving to watch it fade from view for what may be the last time during this expedition.
The seas were exceptionally calm since leaving the Maldives over a month ago, quite unexpected for this time of year. However, over the last week, the strong northerlies that prevail for most of the year in the northern Red Sea whipped up and tore through our mainsail. Peaking at 35 knots, the winds are persisting, causing the boat to pitch and roll at most inconvenient angles. It is inadvisable to stand, walk around or even sit without sufficient grip, and during meal times, plates, cups and utensils demonstrate an infuriating affinity for the floor.
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The crew enjoyed a friendly reception from the people of Eritrea.
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Photo : Chris Johnson |
Sighting cetaceans beyond 100 meters is virtually impossible now as Odyssey buries her bow deep into the swell in a bid to inch ahead. The torrid sea sends bubbling, frothing water bursting through the scuppers and sweeping across the decks, while salt laden spray obscures the view of the helmsperson. We have no choice now but to motor directly into the wind and toward the narrow entrance of the Gulf of Suez, 30 long miles ahead. Two more days and a further 180 miles will bring us to Port Suez and the southern end of the Suez Canal.
This is Genevieve Johnson speaking to you from the Odyssey in the tumultuous northern Red Sea.
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Log written by Genevieve Johnson.
