Science as Inquiry
Bears hibernate, whales migrate. Winter has arrived, and for many species of whales the season signals the annual trip to their breeding grounds. All baleen and many toothed species are migratory. Some species, like the humpback, the California gray whale, and the Northern right whale, have well known migration patterns because they are close to shore in both summer and winter. Other species, like the fin, blue, and minke whales, head out into the open ocean in winter and are harder to find. Some whales still elude scientists for almost six months of the year!
In the summer, whales live in northern waters where their food is abundant. They build up their blubber for the long migratory journey because the food supply is scarce in the southern waters where they bear their young. Whales must give birth in warmer waters because their calves' blubber is not sufficient to insulate them from the colder waters. After 2-3 months of care and nourishment, the calves are ready to make the long journey north with their parents. Unfortunately, it is natural that some mortalities occur during such an arduous trip.
The California gray whales make the longest annual migration of all marine mammals, a round-trip journey of 10,000-12,000 miles. Their journey begins in the Chukchi and Bering Seas. From October to February they are traveling south to Baja, and then from February to July they make the trip home again. Last year their mortality rate was higher than normal, with more adults dying than normal. It is possible that these adults didn't get enough food to sustain them for the length of their travels because their food supply may have diminished. Researchers have noticed changes in the food chain in the Bering Sea which may be part of an even larger disruption of ocean temperature and biomass patterns. Such changes can have far-reaching implications. Visit the WhaleNet site and click on Teachers then Gray Whale Migration. Select the Whales section of the article from The Orange County Register, and you will find an interactive migration map (Shockwave required) along with other interesting gray whale information.
The Northern right whale is one of the most critically endangered marine mammals with perhaps only 300 remaining in the North Atlantic. Part of their habitat is transversed by shipping lanes, and since the right whales are so slow and float much of the time, they are most threatened by collisions with ships. The National Marine Fisheries Service designated an area off the Florida and Georgia coast that includes the right whales' calving grounds as a critical habitat for the migratory whales. The Northern Right Whale Monitoring Project uses existing Navy technology to detect, identify, and track Northern right whales within the designated critical habitat. A report of a right whale is sent to an Early Warning System, which warns all ships in the area so they can avoid the animals.
Enter the WhaleNet site and click on Teachers then Right Whale Data and Information Page. Select the Early Warning System Data for Georgia and Florida, then click on 1999-2000. There you will find right whale sightings data and a map on which to plot your sightings. Next to each data point, make a note of how many adults and how many calves were sighted. For some related activities and questions, scroll down to Tools and Links and click on Education Activity.
For an exciting on-going activity, follow along with the Journey North site starting in early February, and track the spring return journeys of humpback, gray, and right whales. News of sightings will be posted weekly, and the site will provide challenge questions as well as the opportunity to pose your whale questions to an expert. If you're on the West Coast of the United States, Journey North wants your help with providing gray whale migration data this spring. Contact the captain of one of the whale-watch vessels in your area and perhaps you will find one who will be willing to provide accurate data for you.
If you are interested in organizing a class whale-watching trip, peruse the list of whale-watch companies affiliated with WhaleNet. There is also a link to whale-watching sites worldwide from the Whale-Watching-Web.
For a wealth of information on whales and other marine mammals, be sure to check out the Marine Mammals page on the Gulf of Maine Aquarium site. The Cetacean Research Unit's Whale Curriculum Guide is also a great resource and includes Background Information and Activities. And, of course, there's always the Bridge's Marine Mammals page for even more useful links.
If you have questions about the Data Tip of the Month or have suggestions for a future data tip, contact Laura Rose, Bridge Data Project Manager.
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