Almost 50 dead pilot whales were found stranded Sunday on a beach in the Argentine Patagonia province of Chubut. The cause of the stranding at Bahía Bustamante, and later death, remain a mystery, according to the regional press.
Experts and researchers from the Patagonia National Centre which monitor wild life in the region have been working since Sunday trying to determine the reasons for the beaching, a common phenomenon among this type of whales. The stranded mammals were found by workers from a local company which collects sea weeds for the extraction of agar-agar.
Mass stranding of pilot whales, which are very social and travel in large groups usually of 20-90 animals are not uncommon and at times can involve up to several hundred of the mammals. The first exams of the stranded whales in Bahía Bustamante, measuring between 2 and 7 meters, showed no evidence of injuries or attacks.
Bahía Bustamante is 170 kilometres north of Comodoro Rivadavia and is an area with coves and several islands very rich in marine mammals and birds.
Stranding can be caused by navigating problems when following the leader, including possible magnetic field irregularities. Pilot whales are extremely pack-minded and will always follow the leader even in risk conditions. Like the larger killer whale, pilot whales are members of the dolphin family. They can be seen along Patagonia waters from May to November, when whale-watching trips are available for tourists.
Pilot Whales are amongst the most common and widely-distributed of the marine mammals in the cetacean order. They are jet black or dark grey with a grey or white diagonal stripe behind each eye, and a large, round forehead (melon). It is sometimes known as the pothead whale because the shape of its head reminded early whalers of black cooking pots.
The long-finned species prefers slightly cooler waters than the short-finned and is divided into two populations. The larger group is found in a circumpolar band in the Southern ocean running from approximately 20° S to 65° S. It may be sighted off the coasts of Chile, Argentina, South Africa, Australia and New Zealand. There are estimated to be in excess of 200,000 individuals in this group. The second population is much smaller and inhabits the North Atlantic Ocean.
This is not the first time this kind of beaching happens in the Argentine Patagonia area: in 1991, almost 200 pilot whales were stranded and died twenty kilometers north in Punta Tafor. Closer in time two similar incidents occurred in 2002 but involving other type of whales.