Nic Deka, regional manager north-west with Tasmania's Parks and Wildlife Service, told Australian public broadcaster ABC that 270 pilot whales are stranded over three different sites.
'Some animals may be simply too big or in an unsuitable location'.
Hundreds of pilot whales are stranded on a sandbar in Tasmania, an island off the southern coast of Australia.
About a third of some 270 pilot whales stranded off Tasmania's remote west coast have likely already died, as authorities enter a critical phase to save the remainder.
Speaking this morning, Marine Conservation Program wildlife biologist Dr Kris Carlyon said today's efforts would be focused on the whales with the best chances of survival.
'In terms of mass strandings in Tasmania, this is the trickiest we've had to deal with, ' he added, saying the mission could take days.
Specialist rescuers are hoping to take advantage of an outgoing tide to save as many whales as they can.
Mr Deka said multiple rescue methods would be trialled and a lot would depend on how the whales respond.
Mass whale strandings off Tasmania's coast are not uncommon, with researchers labelling the state as a "global hotspot" for strandings, ABC News reported.
It is not known why whales - which travel together in pods - sometimes beach themselves.