:19:02
under the lengthening daylight.
:19:06
So rich are the waters
:19:08
humpback whales swim nearly
4,000 miles from Hawaii
:19:13
to revel in Alaska's
season of abundance.
:19:48
Humpbacks fast for eight months
:19:50
in the relatively sparse waters
of the tropics
:19:53
where they breed and give birth.
:19:57
For survival, they depend
almost entirely upon the krill
:20:01
and small fish
that concentrate here in summer.
:20:06
To capture
the immense quantities
:20:08
of food they need
:20:09
some humpbacks have devised
an extraordinary technique
:20:13
of cooperative feeding.
:20:16
Diving in unison
:20:17
they surround
a school of herring
:20:19
while one or more
sings a ritual feeding song.
:20:27
Simultaneously, a whale blows
a circular net of bubbles
:20:32
around the fish.
:20:40
Then, as the trap is completed
:20:42
the entire group rockets upward
through the bubble bath.