From Anne Smrcina Stellwagen Bank National Marine Sanctuary Plymouth, Massachusetts
You've asked some marvelous questions, so many that it will take me several days to get all the answers out to you. I've decided to do it in stages -- so here's part 1.
Libby, Misty, Pat and Mrs. Clay of Wiscasset, Maine asked:
Q. What is the major cause of the whale population decreasing?
A. Decreased numbers of whales occurred from hunting in the 1800s and early 1900s. The numbers now seem to be increasing for most species--for example,the gray whale is near its pre-exploitation numbers and has been taken off the endangered list (although it is still listed as threatened).Likewise, there has been some discussion of de-listing the humpback whale.
The right whale has not been as successful in recovering-- its numbers are still extremely low (300-350) in the North Atlantic population. A study indicates that the population has been increasing at a rate of 2.5% a year for the years 1987-1992. And that the rate was 1% in 1993 and -2.8% in 1994. These are not large numbers, and there is some concern about the low calving rates and continued mortality from ship collisions.
Other possible causes of whale deaths are: ingestion of plastics and other debris; entanglement in fishing gear; and degradation of habitat.
Q. How can we better protect the whale population?
A. We can practice safe boating -- stow debris, don't throw it overboard. Boaters can keep lookouts in known whale feeding and breeding grounds, and keep their speeds low. If boaters come across whales, they should keep their distance and not harass the whales -- this is especially important in their breeding and calving grounds. We can support whale research programs and environmental protection programs. Remember, once a species is gone, it is gone for good. Extinction is forever (no matter what they say in "Jurassic Park"). We have to all work together to make sure that all species, not just the whales, are protected for future generations -- there may be many wonderful things we can learn from these creatures that we have no understanding of today.
From Lo-Inyo Middle School, Lone Pine, CA comes this question:
Q."How do the whales find their way north and south? How do they get there if hey can't see what it looks like? How do they know when they get there?
A. I asked Phil Hamilton of the New England Aquarium about this -- "These are very good questions, scientists wish they knew the answers" was his reply. He reports that we don't really understand how the whales navigate from their northern feeding areas to their southern calving grounds. Some believe the whales use geographical features; the whales might recognize water changes such as taste, salinity, temperature, the sound of the area, or the currents. They may use the stars in an innately understood process, or they may have to learn parts of the migration from their mothers. We really have no idea at this time.
Q. Another question for Phil from Colin Holm in Houston, Texas asked: "In Bermuda, do humpbacks come in close to the shore? Do whales seem to be attracted to the whale watching areas?
A. Phil reports that whales do come in quite close to Bermuda at times, particularly the south shore. There is a coral reef around the island that usually keeps whales a little distance from the island, but some whales have been seen among the coral heads. Humpbacks and dolphins are seen in this area -- but there are no sea otters or sea lions in Bermuda. The second question should be reversed -- whale watching has happened because of the whales, and tends to congregate in areas of known whale sightings. Humpbacks seem to be curious whales -- and if their not busy feeding or involved in social behavior, they have been known to check out the whale watching boats. Other large whales usually don't exhibit the level of curiousity of humpbacks - - although the smaller cetaceans such as porpoises and dolphins are often seen near vessels. The reasons whales are found in particular areas is usually based on the areas ability to meet the whales' needs -- such as supplying a good amount of food or a sheltered environment to nurse youngsters.
Q. Larry Betts, a fifth grader from Archbold, Ohio asks:
A. "How high does a humpback whale jump? Phil Hamilton notes that although humpbacks are the acrobats of the great whales, they really can't get their whole bodies out of the water in a completely vertical jump. He estimates that the maximum height is about 35 feet (an adult humpback averages 50 feet in length).
Q. Kim Rogers, Melissa Brown, Becca Olson and their 6th grade teacher Ellen Eigner of Lily Lake Elementary School in Stillwater, Minn. write:
Q. How long do the babies stay with their mother?
A. For baleen whales, about 1 year.
Q. Does a family of whales stay together for life?
A. Baleen whales have no long-term bonds. After the initial mother-calf pairing and nursing, the juveniles are on their own. Sometimes two or three whales will stick together for a short time. In the book "The Lives of Whales and Dolphins" (Henry Holt Publishers, 1994), Richard C. Connor writes:
"If you are ever lucky enough to see a baleen whale, it will probably be traveling alone or with no more than four or five others. That doesn't mean, however, that it isn't part of a larger social group. If one definition of a group is 'individuals who are in contact with one another,' and in many species -- at least some of the time -- individuals may form part of an aggregation of tens or even hundreds of whales. These larger groups are especially prevalent on the feeding or mating grounds or often during migration between the two. Evidence suggests that most of these baleen groups are transient, with members coming and going, often never to be seen again with the same individuals.' (However, large groups in the feeding grounds stay together without intermixing -- such as the Gulf of Maine feeding group or the Gulf of St. Lawrence group.
Although all the whales go to the Caribbean, they separate out into their unique northern groupings -- always to return to their "home" base.) Odontocetes or toothed whales, on the other hand, have been known to form stable groups that may last a lifetime.
Q. How fast can the whales swim? The normal cruising speed for the right whale is 3-6.5 knots. For the humpback, cruising speeds range from 3-9 knots. Rights are not known for swimming fast.
Q. What percent of their body is blubber?
A. The humpback whale averages 30-50 tons (males average 47 feet in length, females average 50 feet). About 1/4 of the humpback whale's total body weight is blubber. The right whale averages between 46-60 feet in length, with a weight of 55 tons (a maximum of 96 tons). About 2/5ths of the right whale's body weight is blubber. Whales are fattest in the fall after the feeding season, and leanest in the spring after their sojourns down south to the calving grounds.
That's all for now. More answers to questions soon.
This is Anne Smrcina from the Stellwagen Bank National Marine Sanctuary signing off.
Journey North 125 North First Street Minneapolis, Minnesota 55401 Phone: (612)339-6959
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