Journey North Gray Whale Spring 2006

Discussion of Challenge Question #2

Meet Kim Shelden,
Gray Whale Expert
(You can send Kim your own questions when Ask the Expert opens at noon on April 7.)

“What might make the gray whale migration run late? List as many factors as you can think of.”

The gray whale southbound migration may have run a little late, but the northbound migration could be early! That makes our question more theoretical, and we have high fives and thanks to these students who combed for clues and sent solid answers! Thanks also to our 2006 expert, Kim Shelden, for sharing the exploration and adding her own thoughts.

"I think the gray whale migration is running late because the whales are finding good food on the way. They are stopping to eat in the kelp fields. It sounds as if the winds are settled and there are mild days, so the whales are not in such a hurry to get to their home." Emily M., Grade 5 Ferrisburgh Central School Ferrisburgh, VT

Kim says: This is a very good answer. While we do see some feeding during the northbound migration most of the feeding occurs when the whales reach Alaska waters at the end of their migration. However. . .

• what if last year before the whales came south they were not as fat because they could not find as much food as they usually do up near Alaska?
• After the long trip to Mexico and then beginning a long trip back to Alaska, what if some of these whales had used up their blubber reserves early? Then they might stop to feed along the way wherever food is available because they are very hungry and this might slow their migration north. [I think most times in this situation we see animals that starve and strand because they cannot find much to eat in the warmer southern areas.]

There are many things that make the gray whale migration run late. One reason is the late formation of the ice pack. Another reason is their predator, the orca. They can also get caught in fishing equipment such as lobster trap lines and fishing nets.
Iselin (NJ) Middle School/7th graders Brian, Rizwan, Louis, and Ronny

We think weather is a big factor for causing the grey whales migration to be late. For example, on February 15 in Michael H. Smith's field note, we saw that there was too much wind and sun. On that day, they did not see a blow or a body.
Iselin Middle School/7th graders Rup, Akash, and Mohammad

Kim says: These are certainly many factors that may delay a gray whale. Avoiding predators may cause some to turn and hide, briefly interrupting their migration, and certainly getting tangled in fishing gear. However, this would only delay a few whales, not the entire population. Weather might effect a whale that is sick or tired but conditions that make it hard for us to see whales (wind that flattens whale blows and glare from the sun that hurts our eyes) don't usually affect the whales because they can go underwater to avoid the worst of storms.

If I were to guess why gray whales might be late migrating north, I would suggest this scenario: It is an unusually cool year so the whales continued farther south into Mexico waters than they have in other years. Scientists in Mexico say during very warm years, gray whales appear to abandon the southernmost lagoons and show up in greater numbers farther north. So maybe on cold years they go back to these lagoons where the water is warmer— adding many more miles to their migration. When they are ready to head north, they now have a greater distance to travel so they show up late at the counting stations in California. How is that for a theory? ;-)