When the giants of the deep blue depths came out in numbers

Was it a case of predator following the prey due to recent seismic activity ask conservationists and biologists
By 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.

Pix courtesy Sandaruwan Abayaratne

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.

(The writer is a marine naturalist)

Show of all shows

Over the weekend, while the nation celebrated the New Year with festivities and feasting, a festival of another sort was taking place off the island’s west coast. As if to join in the revelry on land, over one hundred Sperm Whales were gathering off the Kalpitiya peninsula in a feeding extravaganza.

On receiving a flurry of reports describing the unusual occurrence - CRIOMM’s (the Centre for Research on Indian Ocean Marine Mammals) Director, Marine Research, Howard Martenstyn was soon scrambling to head back to Kalpitiya where he had been working at sea. Brother Dallas Martensteyn –hotelier and pioneer of the whale and dolphin watching in Kalpitiya, who had his boats at sea, soon helped CRIOMM’s Convenor Dr. Hiran Jayewardene, set up a conference call with personnel on the vessels to monitor the unusual activity in an attempt to get a definitive identification of the species, numbers etc. and get a better understanding of what was happening at sea.

Howard and the whales

Previously, a gathering of about 100 pilot whales led by about 40 bottlenose dolphins had been seen by Howard in the area. Wildlife authorities had been notified of over 100 Sperm Whales floating like logs - (called “logging” by scientists) as being near the Bar Reef Sanctuary and also close to the Norochcholai Power Plant.

While on line, Keith Wanigasekera, Manager of Dolphin Beach on one of the boats reported two Blue Whales surfacing by his boat and travelling south. Switching to another boat further north, operating off Talawila, veteran operator Maithri Liyanage from Ruwala Resort, Talawila reported an encounter with more whales – Sperm Whales, about 40-50 moving south. Maithri further reported that he had also been with 30+ Sperm Whales the day before moving south.

Next morning, two boats resumed the search, with Howard heading to sea on a forty-five degree transect from Dolphin Beach, Ilanthadi where he has his boat. Meanwhile, Maithri departed Kandakuliya on a northerly heading but was soon drawn eastward by a call from another observer, missing the spectacular encounter Howard’s team had.

At 7:40 a.m. there were over one thousand spinner dolphins dotting the sea off Norochchalai prompting a call from Howard to all resorts to come and see the dolphins. While waiting for Maithri, Howard’s boat had first seen a few Sperm Whales, and then - looking for signs of feeding, observed large cuttlefish some over 3 kg. confirming the presence of the Sperm Whales’ favourite food source. Soon their boat was surrounded by whales feeding across a wide area of sea in pods of varying sizes.

“They were lob-tailing and diving around us. Spinners and Sperm Whales spread about two km in numerous pods of one, two’s and mostly eight to twelve, with around thirty individuals making up the largest group of Sperm Whales. They were seen logging, travelling, and fluke-up diving. They were also observed tail-slapping with loud thumps on the water seemingly to push the food source towards others feeding on the cuttlefish. One Sperm Whale displayed bleeding injuries and scratch marks around the mouth and front raising suspicion as to how they were made,” said Howard.

As Howard summed-up “The overall activity was one of milling and feeding while travelling north.” The focus of his studies at present is correlation between distribution and various oceanographic features, as well as discerning local and regional/sub-regional migration patterns.

This recent encounter is one of many, researchers who are working with CRIOMM have experienced in endeavouring to develop a better understanding of marine mammals in the Indian Ocean with special reference to Sri Lanka. The principal thrust of CRIOMM is capacity- building for better management of marine mammals in the Indian Ocean Sanctuary area, including Sri Lanka and to consolidate and interpret information necessary for long-term management.

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