I’m back home after 12 days spent in Sri Lanka with the aim to photograph the blue whales under and over the sea surface. I leaded two groups, each of 4 people counting even myself. For these activities I think “the lesser the better” , and in fact everybody was able to see and photograph the whales underwater.
Blue whale, Balaenoptera musculus is the largest animal ever known to have existed. During the 20th century, the species were valued preys in the whaling industry and the blue whale was nearly exterminated before receiving worldwide protection in 1967. Although commercial whaling no longer represents a threat, nowadays the global climate change and its impact on ocean euphausiids (krill – shrimp-like crustaceans), that are the blue whales’ major source of food, makes this cetacean particularly vulnerable.
During the two weeks we’ve been in Sri Lanka, we navigated for 6 to 7 hours a day, looking to encounter the whales. Sometimes we were more of 20 nautical miles from shore : no bare eyes sight of land or coasts from that distance.
We experienced days with excellent sea conditions but also few days with raft sea; only one day we had to come back to the harbour because of the bad weather conditions.
Some days we saw many whales, few days only one. Some whales were more cooperative than others : they swam slow and remained longer close to the surface; other whales dived before we were able to approach them. Every day was different, but I’m more then satisfy for what we have seen and photographed.
The blue whales dives for a period of 10 – 20 minutes each time, and usually feed at depths of 100 m. or less. Average travel speed is around 22 km/hr, although they may swim as fast as 48 km/hr if they perceive a danger.
Blue whales are believed to have excellent hearing, especially at low frequencies, which is a must in the dark ocean environment.
During summer months, blue whale populations migrate towards the poles, looking for their food that lives in cooler waters. During the winter months, they migrate back towards the equator and the warmer waters, for breeding. Because the seasons are opposite in the northern and southern hemispheres, the net result of these movements is that the northern hemisphere and southern hemisphere stocks of whales does not mix. Like many other baleen whales, it feeds in cool waters at high latitudes, and generally migrates to warmer temperate and tropical waters to breed and give birth.
It seems that in Sri Lanka the species may be resident year-round.
The blue whale is found mostly in cold and temperate waters and it prefers deeper ocean waters instead of coastal waters.
The largest recorded length of a blue whale is 33.5 m, but sizes tend to be in the range of 25-30 meters. Females are up to 10 m longer than males. A 33m blue whale would weigh more or less 200 tons.
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