Scientists in Argentina are investigating what may have caused a spike in the mortality rate of southern right whale calves in the country's Atlantic coastal waters.

A record 113 calves of this whale species washed up last year on the shores of the Valdes Peninsula, in the southern Patagonian province of Chubut, or a third of the southern right whales born in 2012, according to Whale Conservation Institute figures.

Even so, the Institute's Southern Right Whale Health Monitoring Program said that species' population has steadily risen over the past decade at an annual rate of between 5 percent and 7 percent.

Researchers working in that area say there are some 4,000 southern right whales in the South Atlantic Region and approximately a third of them congregate along the Argentine coast.

The scientists have not yet found an explanation for last year's increase in the whale calf mortality rate.

"Within a decade, we'll see a significant reduction in the number of whales born" because these animals have their first calves at the age of nine on average, the Institute's scientific director, Mariano Sironi, said.

But not all experts are as pessimistic about the future.

Oceanographer Guillermo Cainne, technical coordinator of the Natural Patagonia foundation, told Efe that that species' overall population would not necessarily decline in the coming years and forecast that it would continue to steadily recover from the mass whaling of the 19th century.

Cainne said scientists have observed that southern right whales have arrived in larger numbers and spent more time in Argentina's coastal waters in recent years.

Whales congregate off the coast of the Valdes Peninsula from June to December, making those waters one of the world's main breeding and calving grounds for that species.

Whale-watching, meanwhile, is one of the main tourist attractions in Chubut. EFE