Gray Whale Migration
By Daryth Morrissey
The Eastern Pacific Gray whale has one of the longest migrations of any mammal on earth. Every year, they swim up to 14,000 miles from their summer feeding grounds in the Bering and Chukchi Seas down to the warm, shallow water lagoons of Mexico’s Baja Peninsula. Being coastal navigators, the whales usually travel within 2.5 miles of shore, which is why they are so easily viewed by humans. In a 24 hour period, they can swim up to 100 miles, but they usually average 75 miles per day. Average speed is 3-6 mph. On average, it takes 2-3 months to complete a southbound migration.
From May to October in their summer feeding grounds, gray whales spend their time sucking up and filtering out up to an acre of crustaceans (gammarid amphipods) from the bottom sediments. During this 130-140 day feeding period, it is estimated that they consume 130,000 pounds of food. This energy is stored in their up to 5 inch thick layer of blubber. They will not eat like this again until they return home. Sensing that daylight hours are shortening, thus not allowing for as much photosynthesis and food, the grays begin their journey southward. The first to leave are the pregnant females, followed by the males and other females, and lastly the juveniles. About 53% of the births occur before passing Los Angeles.
From January to June, the grays are in their winter birthing and mating grounds in Mexico. Here the males spend their time vying for new parenting rights, and the new moms feed and train their babies. Gray whale milk is 53% fat, as compared to humans which is 3-5% fat. A newborn calf can consume 30-50 gallons of milk each day, gaining up to 50 pounds daily! The babies need to store this energy in their blubber, for the long migration home and to insulate their bodies from the cold Arctic seas. Once all of those competing males have left, the moms (cows) train and strengthen their calves on how to swim at the mouths of the lagoons as the tides go out. They can also been seen breaching, jumping out of the water, and spy hopping, sticking their heads out of the water.
Through February and March, the first to leave the lagoons are again the males and females without new calves. Pregnant females and nursing mothers with their newborns are the last to depart. So get on a boat! There are several whale watch companies to choose from in Dana Point, Newport Beach, and Long Beach. Or, bring your binoculars and watch from shore.