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Humpback Whale Migration Update: March 18, 1998
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Migration Route of Atlantic Humpback Whales Map courtesy of |
- Humpback Whale Sighted Off Florida Coast
- Whales in Great South Channel off Massachusetts
- Challenge Question #4
- Extra: Humpbacks in Hawaii
- Challenge Question #5
- Discussion of Challenge Questions #1 and #2
- Last Call: Name a Humpback Whale!
To: Journey North
From: Anne Smrcina
Greetings from the Stellwagen Bank National Marine Sanctuary.
Humpback Whale Sighted Off Florida Coast
We received a report from the Right Whale Research Team flying aerial surveys off the Florida/Georgia coastline
that a juvenile humpback whale was spotted on March 1st. It was presumed to be moving north. Coordinates for that
whale
were 30 38.6N, 81 25.5W.
I haven't had a chance to talk to anyone from the Caribbean these past two weeks, but I suspect the whales are
still there in good numbers. It's usually about this time, or perhaps another week or two, that the whales start
to move on out and head north.
Whales in Great South Channel off Massachusetts
A survey cruise from the National Marine Fisheries Service
also spotted 5 humpbacks in the Great South Channel (southeast of Cape Cod). Can you locate this area on a map.
The Channel is a major shipping lane along the east coast, cutting between land and the shallow area known as Georges
Bank. Here's a Challenge Question for you:
Challenge Question #4
"Why would whales want to stay in the Great South Channel even though large ships are constantly moving through the area?"
(To respond to this question, please follow
the instructions at the end of this report.)
It is not known if these are migrating whales or whales that stayed in the area throughout the winter. There have
been reports from fishermen that whales were seen all winter long on the northern portion of Stellwagen Bank feeding
on the abundant sand lance (a small bait fish).
Extra: Humpbacks in Hawaii
I thought you might also like to know about another group
of humpbacks-- those in Hawaii. I talked to staff from the Hawaiian Islands Humpback Whale National Marine Sanctuary
to see if whales are still there. The Hawaiian Islands are a major breeding and calving ground for one of the Pacific
populations of humpbacks. I was told that this is still part of the peak season, and that the northward migration
does not appear to have started yet. When it does happen, the whales move out en masse.The Hawaiian Islands Humpback Whale National Marine Sanctuary was designated by Congress in 1992 (the same time as the Stellwagen Bank Sanctuary) but only just received approval by the state for its Management Plan and Environmental Impact Statement. The dedication ceremony was February 16th. One of the first major actions of the sanctuary was to fund a research study on the humpback population. Here's another Challenge Question for you:
Challenge Question #5
"Where do you think these Hawaiian humpbacks go to feed during the summer months?"
(To respond to this question, please follow
the instructions at the end of this report.)
Discussion of Challenge Questions #1 and #2
Challenge Question #1 asked, "What do you think humpback whales are eating when they come up to Stellwagen Bank and the Gulf of Maine, and what are they eating down in the Caribbean right now?"
If you read carefully at the start of today's report, you got part of the answer. When they are up north at
Stellwagen Bank, which has a nice sandy surface, they are feeding primarily on sand lance -- a small bait fish
which is also called the sand eel. Obviously, by its name, the fish likes sandy habitats where it digs itself into
the sediments to hide. The fish is about 5-6 inches long and pencil thin. Out of the sand, these fish often crowd
into large schools or "balls," making feeding quite efficient for the humpback whales.
Elsewhere in the Gulf of Maine, where sandy bottoms are not as prevalent, humpbacks may be feeding on herring,
mackerel, and other small fish, as well as krill and squid. If these prey items are on Stellwagen, the whales will
eat them too. Down in the Caribbean the whales are not eating.
The mothers spend their time nursing their young, while the other adults are busy mating. The warm waters of the
Caribbean are not as productive as northern waters (less phytoplankton, less zooplankton, less fish). That's why
they are so clear and the northern waters so murky. The whales usually feed enough in the northern waters to last
them through their winter's fast.
Challenge Question #2 asked, "Why do you think this voluntary breathing is important in whales? And,
if these whales are voluntary breathers, how do they sleep?"
Voluntary breathing is an important adaptation for whales. They must constantly be aware of their location in the
water. Since they are mammals and can drown if they flood their lungs with seawater, they must know when it's safe
to take a breath. It is believed that the area around their blowholes is very sensitive and allows them to know
when they have broken through the surface to the air.
Voluntary breathing means that the whale must keep its brain active. So how do they sleep? Scientists believe it
is done half a brain at a time (based on studies with dolphins). Whales are known to log at the surface -- a resting
behavior. Boats can often approach quite close at this time during whalewatching, and it is a time when animals
can be in great danger from fast-moving boats unaware of their presence. The animal has probably shut down half
its brain, keeping a part active enough to sense when it is moving away from the surface, when to make adjustments
with its flippers and flukes, and when to take a breath. After a while the whale will become fully awake
I've seen whales make this transition from resting to active behavior -- it is quite obvious. The whale might start
to move off quickly or dive at this time. Eventually, the whale will log again, shutting down and resting the other
side of the brain. In this way the whale allows both sides of its brain to rest. It never goes into a deep sleep.
LAST CALL: Name a Humpback Whale
Challenge Questions #3 was to name one of the new humpback whales. I need your answers by Friday, March 20 at the latest. Send them in ASAP. I'm looking forward to representing you at the whale naming party.
Until next time, this is Anne Smrcina, education coordinator of the Stellwagen Bank National Marine Sanctuary, signing off.
How to Respond to Journey North Right Whale Challenge Question # 4 (or #5)
Important: Send ONLY ONE answer in EACH e-mail message.
1. Address an e-mail message to: jn-challenge-hwhale@learner.org
2. In the Subject Line of your message write: Challenge Question # 4 (or #5)
3. In the body of EACH message, answer ONE of the questions above.
The Next Humpback Whale Migration Update will Be Posted on March 18, 1998.