Southern right whales were once mercilessly hunted, in fact in the first half of the 19th century whale hunters have killed close to 50,000 southern right whales, and they were on the brink of extinction before they become listed as endangered in 1937. Thanks to conservation efforts their numbers have significantly recovered, and according to the most recent numbers there are 7,500 southern right whales remaining inhabiting areas around South America, South Africa, Australia, and some islands.
But new problem is arising, namely the increased calf mortality. In the past five years in the waters off Argentina's Patagonian coast, which is one of the most important breeding grounds for southern whales close to 300 young calves were found dead.
Scientists still try to determine the possible reasons for these deaths and there are different theories involved: possible reasons include biotoxins - naturally occurring poisons - disease, environmental factors, lack of prey, particularly the tiny krill that make up the bulk of the southern right whale's diet. There is also the theory that blames the effect of gulls, which can act like parasites, gouging skin and blubber from the whales' backs.
Scientists realize that they need to examine all the possible causes for these deaths and find the adequate solution that would stop further calf deaths.
Particularly worrying is the fact that many young dead whales have been found around the Peninsula Valdes in the province of Chubut, where approximately one third of the global population of southern right whales is thought to use the protected bays for calving and nursing between June and December.
This mystery needs to be solved as soon as possible or we could see a sudden decrease in southern right whale population.
Southern right whales are ones of the largest animals in the world, when fully grown they weigh up to 90 tonnes.