Dozens of dolphins have died after a pod of more than 150 stranded on a remote beach in Australia's southern island of Tasmania, environment officials said Wednesday.A pod of 157 dolphins from a poorly understood deep-sea species was believed to have stranded in the past 48 hours -- with "approximately 90" still alive as of Wednesday morning.

The dolphins or false killer whales were found on an isolated beach in northwest Tasmania. About 136 are alive, but authorities say it will be a challenge to refloat them.

After 157 false killer whales were stranded on a Tasmanian beach, experts said only 90 have survived. Following a few failed "refloating" attempts to return the whales to the sea, the remaining survivors are expected to be euthanized.