Posted by: The ocean update | April 22, 2012

When the giants of the deep blue depths came out in numbers (Sri Lanka)

Sunday, 22 April 2012 (Ranil Nanayakkara). The unique sighting of a school of more than 100 to 150 sperm whales that marked their presence in the waters off the north western coast of Sri Lanka with the dawn of the Sinhala & Tamil New Year raised many questions for conservationists and marine biologists. First sighted approximately six km west of the “Bar Reef” off Dutch Bay in Kalpitiya on April 14, the next reported sighting was approximately 7 km west of Kandakuliya.

The fishermen of the area who were the first privileged to witness this wonderful sight, also realized its unique nature, as this was the first recording of such a large gathering of these giants of the sea in the Kalpitiya area.

These giants were not alone at this location as a few Blue Whales, the largest animal on earth, a large number of spinner dolphins and a pod of Pygmy Sperm Whales were also observed in the immediate area.

Observing these giant marine mammals at close quarters from a boat out at sea, it was seen that they were of uniform size, with the odd “big one”, an indication that only a few males or “bulls” as they are called, were in the group. This is a clear indication that the gathering was for a purpose other than breeding.

Sperm Whales generally travel in loose groups, these being usually of non-breeding males, the other grouping being of females with calves. In some instances, several large males have been observed in the close vicinity of these female/calf groups. Older males tend to be generally solitary according to observations.

Significant for this unique sighting is that this closely followed the seismic activity off the Indonesian coast with a tsunami alert for the littoral states of the Indian Ocean and the African coastline covering 28 countries. Also significant is that, according to local fisher folk, dolphins and whales disappeared from the Mirissa area, to the south of the island.

While several theories and suggestions have been put forward for this presence of Sperm Whales, detailed close observations at first hand brought up some very interesting facts.

There was a large aggregation of sea birds of several varieties feeding in the immediate area and alongside the whales, attracted by the large shoals of fish species, such as Bonito, Yellow fin Tuna and other smaller varieties such as “Bollo”, in addition to other species such as squid, which are the favourite foods of these whales. The fisher folk too confirmed the unusually high prevalence of these “prey” species in their catches.

Close observations also indicated that the whales were obviously feeding and resting on the surface before making long dives, not displaying breeding behaviour, the lack of “bulls” in the group being another strong indicator of their intentions.The presence of the smaller prey species are an indication of the presence of the nutrients necessary for their feeding, which is indicative of the “up-wellings” of the waters, possibly resultant from the seismic activity to the east and it could be surmised that the “prey” was followed by the “predator” up to the gargantuan size of the Sperm Whale.

Significant also is the fact that the location of the group, on the north western waters of the island, sheltered as it was from the direct action of the strong currents or the tremors and vibrations of the seismic activity, with the land mass of Sri Lanka between them, would have provided an ideal shelter and a food source for the smaller creatures, who in turn were followed by their “predators”.

Of further significance is the fact that whales are quite sensitive to tremors and vibrations, while it is important to take into consideration that tectonic plates worldwide recorded seismic activity coincidentally.

Another matter of concern to marine biologists and conservationists is that of the great whales, only the Sperm Whales are known to strand themselves en masse and whether their gathering in large numbers in these shallow waters could be a prelude to this“collective suicide”. Their behaviour so far does not forebode such a tragic end to one of the most wonderful creatures that adorn the waters of this blessed island.

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