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Gray Whale Migration Update: May 3, 2000
Today's Report Includes:
- Latest Highlights from the Gray Whale Observation Posts
- This Week's Migration Data
- Challenge Questions #19, #20, and #21
- Beast Feast
- How Far Can They Go?
- Tom Lewis Reports: At Journey's End
- Strandings: Response to Challenge Question #15
- Whale Hunts: Response to Challenge Question #17
- Try This! Cycling Through Controversy
- Whale Sounds: Response to Challenge Question #18
- Year-End Evalution: Please Share Your Thoughts
Latest Highlights from the Gray Whale Observation Posts
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Click on map to enlarge |
Is the northbound migration running later this year? Reports say there are still 20 cow/calf pairs in San Ignacio Lagoon. NO whales are headed south anymore, and northbound peaks have passed at many of our observation points. The American Cetacean Society (ACS) Census reports 1011 northbound gray whales as of April 30. In the sixteen years of the ACS census, this year's April 28 count of 993 northbound grays is the fifth lowest in sixteen years of the ACS census, and the 13 cow/calf pairs the third lowest.
How's the whale viewing at Nelson Lagoon School (55.92N, 161.35 W), where the first whale appeared on April 8? Principal John Concilus writes, "We went to the beach twice to get video, and no whales...BUT, every time I don't have a camera I see them. They are increasing in regularity. The weather has been bad the last week, but we plan on taking five of our kids and just WAITING with a video camera NEXT NICE DAY! Some are just 30 to 50 FEET off the beach."
Susan's report tells of dangers that abound along the whale trail. Strandings are being reported. People in Bellingham Bay (48.73N, 122.55W) are concerned about whales hanging out in the harbor, where they are exposed to contaminants. Pods of orcas are lurking, and on April 28 a boat pilot saw eight killer whales attack a cow/calf pair off the Channel Islands (32.49N, 118.45). You'll find more details in Susan's full report, as well as the answers to the challenge questions below!
After you read Susan's full report and look at the data, you'll be able to fill in the blanks to answer:
Challenge Question #19
"It is uncommon to see such a large group of transient orcas unless _____."
Challenge Question #20
"Of the 1011 Northbound gray whales counted by the ACS Census, the percentage of cow/calf pairs is ______."
Challenge Question #21
"More than 500 northbound whales were sighted on these two April dates: __ and __."
(To respond
to these questions, please follow the instructions below.)
Beast Feast
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"It is generally understood that gray whales migrate to their northern feeding area to feed on the dense and rich benthic (bottom-dwelling) community of the Bering and Chukchi seas. The short baleen of the gray whale has apparently been adapted for collecting this benthic infauna. Scientists have noted that the baleen is often worn and there are generally fewer barnacles and skin abrasions on the right sides, indicating that the whales have a side inclination to their feeding. With their mouth 10-20 cm above the surface of the ocean bottom, they create a pulsating suction by depressing their tongue. The suction pulls the prey from a depth of 20-30 cm. Their feeding tracks are slightly curved and measure 1 to 3 meters long and from 0.5 to 1.0m wide (Nerini, 1984).
"The whales' preferred feeding grounds in the Bering and Chukchi Seas is a shallow region less than 50 meters deep in the northern Bering Sea, and an area less than 68 meters in the southern Chuckchi Sea. The Chirikov Basin, located north of St. Lawrence Island (63.50N, 170.17W) and south of the Bering Straits (66.00N, 168.50W), is dominated by a community of amphipods, Ampelisca macrocephala. Pull out a good map and you can locate these places. Gray whales also feed in the Western Bering Sea, the southern capes of St. Lawrence Island, the southern Chukchi Sea, and the north side of the Chuckchi Peninsula. The prey in these areas is not limited to amphipods but includes cumaceans and isopods (Nerini, 1984). (These are all scientific names for very small creatures, and you might be able to find pictures of them with some research.)
"Besides benthic feeding in some areas, gray whales along their migratory route have also been reported to feed on pelagic species such as schooling squid, krill, small bait fish such as capelin, crab larvae, herring eggs, and ghost shrimp. Whale acrobatics are catching the attention of whale watchers off Kodiakís Narrow Cape. Whales in the surf are standing on their heads with their flukes in the air or lying on their sides with flippers out of the water! According to James Darling of the West Coast Whale Research Foundation, these whales may be feeding on mysids, which hide under rocks. Gray whales feeding on planktonic species such as crab larvae can be seen skim feeding with their upper jaws above the surface of the ocean, biting at their prey."
How Far Can They Go?
Belukhas (or Belugas) and Bowheads are up as far as Point Hope (68.33 N, -166.75W) but no grays have yet been reported that far north. Check out the latest ice maps for open waters and see when you think they'll get there:
Tom Lewis Reports: At Journey's End
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"The year 2000 has been a very interesting year for gray whales. The best news was the cancellation of the proposed salt works project in Laguna San Ignacio. But the not-so-good news is the higher than usual number of gray whale deaths along the migration route, and the approximately 30 dead whales stranded inside the lagoon."
Tom reminds us that the trip takes gray whales 2-3 months to complete, with traveling 24 hours a day. Scientists have found no real difference in the whales' swimming patterns during nighttime hours. So how do the whales rest along the way? What thoughts do scientists have about the high number of mysterious whale deaths along the migration trail? Why don't we know any answers for sure? Read Tom's full report:
Strandings: Response to Challenge Question #15
Last time we asked, "What are some reasons why whales get stranded?"
Whales often get stranded or beached when there's something else wrong with them, such as illness. These mammals can die from pneumonia when water gets in their lungs. But they may strand for reasons other than illness. Mass strandings can occur when something goes wrong with their ears. Sheyna Wisdom explains that the acoustic system within marine mammals is extremely important; marine mammals don't have or need a sense of smell, but a large part of their brain is dedicated to perceiving sounds and making sounds. They use sounds to communicate, so hearing is the most important sense they use. The toothed whales use sound to navigate by echolocation--producing sounds, listening to their echoes and getting mental images about objects. Sheyna says, "As far as we know, baleen whales do not echolocate. Blue whales can use their long low sounds to navigate around an island."
While the reasons for strandings aren't exactly known, one thing certain: As a whale lies on land, its body weight will eventually crush its internal organs and the whale will die. Whales are able to grow to such immense size because salt water buoys and supports their weight.
No Dorsal Fins
Response to Challenge Question #16
Last time we asked you to make a connection between the ice and the gray whale's lack of a dorsal fin. We asked: "Why don't gray whales have dorsal fins? Do you think this feature of their anatomy is an adaptation? Explain your answer."
Gray whales don't have dorsal fins, but instead have 6 to 12 knuckles or bumps along the dorsal ridge. The lack of dorsal fins on grays and true Arctic whales, such as the Beluga and the Bowhead, is possibly an adaptation that enables them to swim among the flow ice without risking damage. However, the gray whales swim farther north only as the melting ice permits, waiting until after the ice is gone. Because of this behavior, people look at changes in the Bering Sea ice maps to help them know when the gray whales will return. Grays and the whales with dorsal fins usually don't swim as far as Point Hope, AK until July!
Whale Hunts
Response to Challenge Question #17
"When so many whale species are endangered, why is the Makah Whale Hunt approved?"
We've mentioned the Bowhead whale hunt as well as the Makah hunt in our recent reports to let you know that, while limited, whale hunting still occurs in some places. Whale hunting is an issue that many people feel strongly about. The whale hunt by the Makah people is a tradition that was guaranteed under a 1855 treaty with the United States Government. When the gray whale was taken off the Endangered Species List in 1994, the Makah tribe moved to resume the practice, citing whaling rights granted under its 1855 treaty. After a 70-year hiatus, the traditional hunt resumed in 1999 with approval by the International Whaling Commission. The Makahs received a 10-day permit on Monday, April 17, 2000 to start this year's hunt. They are allowed a take of 5 whales again this year. Susan Payne reported that four or five families are planning to take part in the hunt. On the first day of the whale hunt, a Makah whaling family came home to Neah Bay, Washington (48.37N,-124.60W), without killing a whale. Meanwhile, the Coast Guard arrested two protesters on that day.
The Makah whale hunt (indeed, all whale hunting) is surrounded by controversy. Tribal leaders insist that the seasonal hunt is a centuries-old tradition that is vital to preserving the Makah identity. Anti-whaling activists fear it could lead to a renewal of commercial whaling. You will find more about the whale hunt in newspapers and on the WWW. When you know the arguments and the issues, you will be in a good position to decide how YOU feel.
Try This!
Look into the issues surrounding the Makah Whale Hunt and have a classroom role-play or discussion. For a lesson in debating values and viewpoints, please see:
Whale Sounds
Response to Challenge Question #18
Along with Sheyna Wisdom's report and recordings, we asked, "Scientists don't know what gray whales use sounds for. What's your guess? (Hint: compare the social system of gray whales to sounds of other animals like dolphins or wolves to see what ideas you come up with.)"
Tough question. Even scientists can only guess at the answers that apply to gray whales. It makes sense to think whales use sound for navigation, contact, species or individual recognition, coordinating activities, or to go with behaviors like feeding, alarm calls, or reproduction.
Sheyna reminds us that for whales and dolphins, hearing is their most important sense because of the importance of sounds in their communication. Did you know that a lot of the shipping noise in the ocean is the same frequency as whale and dolphin communications? This may mean that human activities can affect the ability of these marine mammals to communicate. Next time you read or hear of sound testing or explosives in the ocean, you may think twice about the effects.
A Whale-sized Thanks!
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How to Respond to Today's Challenge Questions:
Please answer ONLY ONE question in EACH e-mail message.
1. Address an e-mail message to: jn-challenge-gwhale@learner.org
2. In the Subject Line of your message write: Challenge Question #19 (#20 or #21).
3. In the body of EACH message, give your answer to ONE of the questions above.
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Journey North |
The FINAL Gray Whale Migration Update Will Be Posted on May 17, 2000.
Copyright 2000 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form
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