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Die-off of whales along Argentine Patagonia alarm scientific community

Thursday, March 25th 2010 - 03:11 UTC
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An International Whaling Commission taskforce analyzed the situation in Puerto Madryn An International Whaling Commission taskforce analyzed the situation in Puerto Madryn

The scientific community is alarmed by the die-off of southern right whales along the coasts of Argentine Patagonia. In the last three years some 300 specimens of these marine mammals have been found dead on the beaches of Valdes Peninsula on the Atlantic Ocean, a number far beyond what would be considered normal, according to scientific experts.

Until 2007, the annual average number of whales found dead on the peninsula, a UNESCO World Heritage Site, was no more than 30, the president of the Argentine Whale Conservation Institute, Diego Taboada, said. That means that the annual average has gone from 30 whale deaths to almost 100, he added.

“It has been established that a die-off like this was a completely unknown phenomenon and nothing like it has been seen anywhere else in the world. It has alerted the entire scientific community,” the expert said.

Sparked by the alert from Argentine specialists, the problem was analyzed this month by whale and health experts from several countries in the city of Puerto Madryn, 1,100 kilometres south of Buenos Aires, at a workshop sponsored by the International Whaling Commission.

“One of the main problems we have is that when whale fatalities are reported and we find them, they have already been dead for several days. The whales literally cook in their own fat, their organs decompose and that stops us from getting samples of their blood or from different organs that would allow us to perform an analysis to determine the causes of death” Taboada said.

In the bays of the Valdes Peninsula in the Patagonian province of Chubut, around 600 southern right whales gather every year, the fifth part of the world population, a phenomenon that attracts more than 100,000 tourists annually.

Veterinarian Marcela Uhart of the Wildlife Conservation Society said that experts analyzing the surge in the mortality rate have ruled out a number of factors that have impacted right whales in other parts of the world.

For example, she said they have ruled out the possibility of the deaths being caused by colliding with ships or being caught in fishing nets as happens to this whale species in other parts of the world where they are in danger of extinction.

Uhart said that there is no clear pattern of death among southern right whales, so that experts even doubt that there is a common cause of death, since there are “innumerable factors” that could have an influence.

Among the causes being analyzed are environmental factors that are changing significantly due to climate change and whale malnutrition.

“The common denominator in the cases analyzed is that the calves are too thin. That is due to the mothers suffering malnutrition because they haven’t found sufficient resources to have an adequate diet” Taboada said.

It could also be that malnutrition “combines with a great number of primipara mothers whose first calves have a high percentage of mortality,” the expert said.

In his opinion, having the International Whaling Commission call this meeting is “really very important” progress in beginning to address this problem and keeping the southern right whale from again facing extinction.

The report prepared at the Puerto Madryn meeting will be submitted for the consideration of the Committee of the International Whaling Commission at its annual meeting, scheduled for June in Morocco.

The Southern Right Whale (Eubalaena australis) is a baleen whale, one of three species classified as right whales belonging to the genus Eubalaena. Like other right whales, the Southern Right Whale is readily distinguished from others by the callosities on its head, a broad back without a dorsal fin, and a long arching mouth that begins above the eye. Its skin is very dark grey or black, occasionally with some white patches on the belly.

The right whale's callosities appear white due to large colonies of cyamids (whale lice).

It is almost indistinguishable from the closely related North Atlantic and the North Pacific Right Whales, displaying only minor skull differences. It may have fewer callosities on its head and more on its lower lips than the two northern species.

Approximately 12,000 Southern Right Whales are spread throughout the southern part of the Southern Hemisphere.

The maximum size of an adult female is 18.5 meters and approximately 130 tons. The testicles of right whales are likely to be the largest of any animal, each weighing around 500 kg. This suggests that sperm competition is important in the mating process. Right whales cannot cross the warm equatorial waters to connect with the other (sub)species and (inter)breed: their thick layers of insulating blubber make it impossible for them to dissipate their internal body heat in tropical waters.

 

Categories: Environment, Argentina.

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