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LatestPhoto
The head of a blue whale. The largest animal on earth breaks the ocean surface alongside the port bow of the Odyssey.

Watch a short video of encounters with Blue whales in an area off the Sri Lankan coast called the 'Basses'.
  Real Video   56k   200k
Photo: Chris Johnson

May 12, 2003
Blue Whales in the 'Basses'
  Real Audio Report
  28k


Log Transcript

This is Genevieve Johnson speaking to you from the Odyssey off the southern coast of Sri Lanka.

To see a Blue whale at sea is something most of us can only dream about. To see more than one in a lifetime is a rarity reserved for a fortunate few. To be in a boat surrounded by 5 or 6 blue whales is an experience so profoundly moving, it inspires us to study these poorly understood creatures and continue the urgent fight for the conservation of whales and their ocean environment. We cannot fail, it is as simple as that!

The other day while collecting data from a widely dispersed group of sperm whales, we sighted a blow so large, it could only belong to a blue whale. We counted at least five, possibly six blue whales in an area of less than two square miles. We could scarcely believe our eyes. Over the past year, we have seen several blue whales in the Indian Ocean but never in such a high concentration. In the crow's nest at the top of Odyssey's mast, Chris had the best view, filming the whales while seated 88 feet above the deck.

Blue whales rarely congregate in large numbers and are usually sighted alone or in pairs. However when food is abundant, several animals may be seen over a relatively small area.

Blue whales are almost entirely dependent on euphausids (krill) as a food source. They capture their prey by accelerating through a large school with their mouth open and throat pleats extended from jaw to navel. In addition to the intended prey, the whale may also engulf 60-70 tons of water. In the largest biomechanical action of any animal on earth, the blue whale closes its lower jaw, expelling the excess water through the fringed baleen plates with its enormous tongue. As the water is filtered out, the prey is trapped inside the mouth.

Blue whales need to consume approximately 3 - 4% of their own body weight every day during feeding season. This can be anywhere from 6-8 tons, constituting 5 million calories for the largest females. It is amazing to think that the largest animal in the world can be sustained by feeding on one of the smallest.

LatestPhoto
Peter passes the pungent orange fecal sample to Chris. The sample will be analysed to determine what the blue whales are feeding on in this area.
Photo: Genevieve Johnson

On average, their dive cycles lasted 12-15 minutes in duration, with a surface interval of 1-3 minutes. This diving pattern combined with the fact that they repeatedly surfaced in almost exactly the same place indicates they are feeding here - lending support to the theory that the deep-water canyons of the 'Basses' are a feeding ground for blue whales.

Blue whales feed at different depths depending on the location of the krill, although krill are typically concentrated from the surface to a depth of only a few hundred meters. The blue whale is not an accomplished diver like the sperm whale that may spend anywhere from 30-90 minutes feeding at depths of up to 2,000 meters.

After one of the animals fluked, we sailed forward and drifted over the 'footprint' - the clear circular patch of water left by the upward beat of the whales' tail when it begins a deep dive. We noticed an enormous orange reddish cloud in the water - the whale had defecated before diving.

Immediately, Peter jumped in with scoop net in hand, and then climbed back on board with the precious but pungent cargo; it's all a part of the job. Reb placed the sample in alcohol, this will preserve the substance until it is ready for shipping back to the United States for analysis. By collecting a sample of the feces, we can determine what these whales are feeding on.

The fact that the feces was orange suggests that the whales are probably feeding on some kind of crustacean, which are also orange in color.

For over three hours, we stayed with the blue whales. This is not difficult to do when they are feeding in one area. However, Odyssey would have no hope of tracking them if they chose to leave. Hydrodynamically perfect in design, blue whales are capable of attaining speeds in excess of twenty knots, a feature that granted them immunity from whalers for centuries. Sadly, the onset of mechanized whaling brought an abrupt end to this temporary reprieve.

We watched two animals dive and surface almost simultaneously. On at least two occasions, it appeared that the trailing whale abruptly changed course as though 'chasing' the lead whale before they fluked together. However, the behavioural significance of this kind of activity remains a mystery, particularly in light of the difficulty in determining the sex of these whales in the field.

LatestPhoto
Krill is the primary food source of blue whales.
Photo: Chris Johnson

After sunset, we drifted over the deep-water canyon and Captain Bob put the halogen light over the side in the hopes of attracting squid, the main prey species of sperm whales. We also hoped to see the small animals the blue whales are feeding on. By the time the crew finished dinner there was quite a gathering of marine life beneath the light. Several squid darted back and forth in synchronous squadrons, although none were interested in taking the lure. Peter managed to catch a small crustacean with a dip net, which is most likely one of the species being consumed by the blue whales. Comparison of the fatty acid and stable isotope concentrations between the fecal sample and the crustacean will give us an indication of the energy extraction by the blue whale's digestive system. In addition, analysis of man-made toxicants in the fecal sample and the krill can indicate to what degree such compounds are being transferred from prey to predator.

Blue whales are found in all of the world's oceans, however, their population structure remains unclear. Like most baleen whales, they migrate annually between higher and lower latitudes, yet in some tropical areas, blue whales are observed all year round. Sightings and strandings of blue whales in Sri Lanka have been recorded during all months of the year and from all parts of the island. This indicates that blue whales may be one of the more abundant species of large whales occurring in Sri Lankan waters, and that at least some of these whales may compose a resident population.

It is estimated that 95% of the world's blue whales were wiped out by mechanized whaling during the twentieth century, this constitutes an estimated 360,000 animals in the southern hemisphere alone. We know that whalers came frighteningly close to removing from the oceans entirely, the largest and most magnificent of marine animals. As a result, blue whales are rare almost everywhere. To see so many in Sri Lankan waters is good news indeed.

Links:

  • Previously, the Roger Payne and the Odyssey crew had encounters with blue whales in Western Australia. Click here to read more.
  • Why are Blue whales so big and so loud? - Roger Payne explains.
  • What is the difference between a 'true' blue and a 'pygmy' blue - Click here to find out more.
  • Meet blue whale researchers Curt and Micheline Jenner.
  • What did the crew report on one year ago in Australia? Two years ago in Papua New Guinea?
    Three years ago in the Galapagos Islands? -> Real Video: > 56k > 200k

    Written by Genevieve Johnson

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