Movement & Migration of Whales

Monday, November 2nd, 2020 | Blog

As is the case with many other animals, several marine mammal species are migratory, often making astonishingly long journeys across the oceans of the world. Many large cetaceans, such as blue whales and humpbacks, migrate between high and low latitudes, moving from their chilly Arctic and Antarctic habitats to tropical and sub-tropical regions in order to breed. Not all members of a species need be migratory; among humpback whales, for example, it is known that juveniles do not migrate along with breeding adults, but remain close to their feeding-grounds all year round, exploiting the relative lack of food competition while their elders are absent during the calving season.

Many cetacean species inhabit vast marine regions. In some species, migration and interbreeding between populations occur on a regular basis whereas, in others, populations remain more distinct: overlapping migrations may occur, but specific populations still remain isolated from each other.

Some cetacean species do not undertake long seasonal migrations but instead make short, frequent journeys. These are normally associated with feeding behaviour. Pelagic night feeders like spinner dolphins are known to make daily inshore commutes, with the result that they are among the species most frequently seen by whale watchers and fishermen. In fact, fishermen often follow dolphin pods to locate shoals of tuna – a practice known since at least Ancient Greek times.

Still, other marine mammals are nomadic, staying on the move all year round with no fixed abode nor any pattern to their wanderings. Their movements may be influenced by oceanic conditions and the availability of food. Individuals and populations of most nomadic species keep within a well-defined territory, but some, like sperm whales, are long-distance wanderers. Sperm whale movements are not truly migratory; instead, the whales seem to make seasonal shifts within a home range of about 1,500km (800nm) in extent. However, the home range itself may shift over the years. Despite centuries of pursuit by whalers, sperm whale movements are not at all well understood. These great whales are found in all the world’s oceans, and individuals may well traverse the entire globe during the course of their 70-80 year lives.

Certain blackfish species are also nomadic in nature, while some bottlenose dolphins participate with short-finned pilot whales in seasonal geographical movements.

Text by Howard Martenstyn, Out of the Blue