Rescuers are trying to save scores of whales beached in the Australian state of Tasmania. Earlier this week, a pod of 270 pilot whales were found washed ashore.  Two hundred more were discovered a short distance away Wednesday.  The stranding of about 470 pilot whales on the west coast of Tasmania is the largest ever recorded in the state’s history.   Two hundred seventy animals were found washed up on sandbars Monday, prompting a rescue operation involving wildlife experts, the police and volunteers. They have managed to return some of the whales into deeper water and coax them back out to sea. It is a challenging task. Pilot whales can grow up to seven meters long and weight three tons.  But dozens of the pod discovered Monday have died, and Australian wildlife experts believe that most of the 200 whales found beached 10 kilometers away Wednesday have not survived.    Yet rescue efforts continue. Wildlife biologist Kris Carlyon says they are focusing on those animals with a realistic chance of survival. “We are going to basically take the animals with the best chance to start with and the ones that we (are) able to deal with.  So, some animals may be simply too big or in an unsuitable location to actually deal with,” Carlyon said.The coastline near Macquarie Harbor, near the town of Strahan, Tasmania, is a known whale-stranding hotspot. In 2011, about 20 sperm whales were beached there, and most died.    Experts have yet to understand why the mammals become marooned.  There are various scientific suppositions.  The whales use echo location to navigate, and one theory is that the whales may have been drawn in too close to the coast in search of food. Other theories have asserted that the Moon’s gravitational pull or perhaps military sonar could be responsible.   There is no definitive answer, and some marine experts believe that mass strandings of whales and dolphins in different countries could all have different causes.  The rescue mission in Tasmania could take days.  Experts say cool and wet weather will help keep the surviving whales alive, but they concede it is a race against time.  
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