Upwelling

[borrowed from http://www.myfourthirds.com/files/0734/1Two_Humpbacks.jpg]

Humpback whales travel thousands of miles from their birthing grounds off the coast of Hawaii and Mexico, all the way to the colder waters of Alaska, because of the nutrient rich waters that help to create lots of yummy whale food in the summer.

The picture above shows two humpbacks that are bubble net feeding.  This involves several whales working together, taking turns being the ones coming up from below to eat the bountiful haul of herring.  The concept is that a few whales swim around in a circle, gradually moving up in the water column while blowing bubbles.  The herring are reluctant to cross the line of bubbles, which get larger as they head toward the surface, so the herring tend to congregate in a dense bait ball.  This makes it easier for the whales following the bait ball from below to gobble up a big condensed glob of food.  If you traveled about two thousand nautical miles to consume a bunch of high fat/protein rich foods that are going to sustain you for the trip back to warmer waters in the fall/winter, you would want to eat as much as possible as quickly as possible.

There are lots of herring up in the waters off Alaska because they have cold nutrient rich waters which promote lots of primary production.  Lots of algae result in lots of bait fish which means a great food source for the charismatic megafauna which make a long sea journey to gain the nourishment they need to produce the next generation of great whales.

Cool, in more than one sense!