What is the name of this movie? "dont despair the whales have survived"?

Okay, strange question, saw a part of this movie once, didn't see the
start, only the ending of part 1. they were in a Submarine after
Nucular bombs had gone off all around the world, and they got a
message what they found out to say "dont despair the whales have
survived" The radiation was spreading all over the world and they
couldn't get any contact other then this, they found the place it was
coming from and when they got their, it turned out to be a News
broadcast center, what had earlier done a program on whales, and it
was this message they were receiving...

i know at one stage they were around australia, i think australia had
a big part in it, something like it was the only place not yet
effected..

I know this is not much info, i saw it years ago, would love to see
the whole movie but got no idea what its called :( can any one else?