How Does the Ocean Affect the Migration of Whales, Sharks & Dolphins?

Seasonal Changes

• The seasons affect weather and temperature, which in turn, affect ocean temperatures. Just like air, the ocean has currents caused by the dynamic heating and cooling of water. In the summer, ocean water is warmer; in winter, it is colder. While heat may help aquatic plant life like algae grow, it's not necessarily helpful to the fish that some whales, sharks and dolphins depend on for food. Since cold water produces better feeding grounds, whales, sharks and dolphins migrate to cooler waters in the summer.

Food Sources

• The food sources for whales, sharks and dolphins vary but most of their food sources, be it plankton, krill or fish move north in the summer (in the Northern Hemisphere). As the smallest, protein-rich food sources seek cool, oxygenated waters farther north, an entire food chain mobilizes in pursuit. The food chain moves because the location of cold water migrates north in the summer and south in the winter with the changing seasons.

Breeding

• Sharks, whales and dolphins are all biologically well-equipped for life in cold, northern waters. That doesn't change the harsh reality of arctic environments, however. While food is abundant, heat is not and that is a physiological stressor. Each species gives birth in the warmest range of their migration. For the mammals, this is likely the least stressful for the young; for the sharks, it may be incidental to their food source. Adult great white sharks, being cold-blooded, may be able to survive in the north, regardless of the cold, but warm-blooded mammals -- the seals they often feed on -- often journey south as the temperature cools, mobilizing the sharks to migrate in pursuit .

Species

• While plenty of shark and dolphin species don't migrate, migration is natural for whales. There are two types of whales: baleen whales, which filter food through gill-like filters, and toothed whales, such as a pilot whale that eat fish like sharks and dolphins. Each type of whale migrates. Of all the whale species and migrating sharks and dolphins, the tendency for migration is greater in the larger animals, which are are less likely to sustain themselves solely on regional food sources.