Oceanography | Vol.31, No.3
RIPPLE MARKS: THE STORY BEHIND THE STORY
OVER THE HUMP Beleaguered in Whaling Days,
Humpback Whales Chart a New Course in the Gulf of Maine
BY CHERYL LYN DYBAS
It’s the longest day of the year, summer solstice, in Stellwagen Bank National Marine
Sanctuary 32 km off Provincetown, Massachusetts. The sea is a promenade of hump-
back, finback, and minke whales.
Humpback fins and tails break the ocean’s surface on all sides of the 15 m research
vessel Auk. Aboard ship, an audience with front row seats watches more than
30 humpback whales perform a ballet. A calf born this year peacefully swims along-
side its mother. Suddenly, it twirls up and out of the sea, pirouettes in a full breach,
and sprays sparkling water droplets in all compass directions before slipping beneath
the waves. Other humpbacks lob-tail, lifting their tail fins, or flukes, free of the water
and curving them down in smacks on the surface.
Humpbacks (Megaptera novaeangliae) are baleen whales that filter-feed with
“strainers” made of keratin inside their huge mouths. Adults range from 12 m to
16 m long and weigh about 36,000 kg. Humpbacks have distinctive body shapes,
with long pectoral fins and knobby heads. Males “sing” complex songs lasting 10 to
20 minutes, which they repeat, sometimes for hours. The whale music may have a
role in mating.
Found around the world, humpback whales migrate up to 25,000 km each year.
Humpbacks feed in summer when they’re in northern waters, then migrate to tropical
or subtropical waters to breed and give birth in winter, when they live on fat reserves.
Humpback whales often work in groups to cor-
ral elusive sand lance. Here, six whales emerge
from a jointly created bubble net. Image credit:
Ilya Raskin; NMFS Permit #782-1719.
NET OF WHALE BUBBLES
What are humpbacks eating—and how do
they get enough of it—to tide them over
until the following summer? In the Gulf of
Maine, the answer lies in a cloud of bub-
bles and a tiny fish.
The whales engage in bubble-netting, a
recently discovered means of feeding on
small fish such as sand lance, also called
sand eels. One or more whales sound, or
dive, then exhale together underwater.
When their bubbles reach the surface, they
form a large ring with seafoam in the cen-
ter. The bubble ring becomes a net, trap-
ping countless sand lance. Seconds later,
one—then several—whales surface in the
ring’s center, huge baleen-lined mouths
open, straining the water, or dragging, as
marine biologists call it, for sand lance.
“Humpbacks have large flukes relative
to their size, providing thrust for quick
maneuvers,” says David Wiley, a ceta-
cean biologist and research coordinator
at the Stellwagen Bank National Marine
Oceanography | Vol.31, No.3