A group of whales is called a pod. A pod usually consists of whales that have bonded together either because of biological reasons (i.e., a mother baring offspring and raising her child) or through friendships developed between two or more whales. A typical whale pod consists of anywhere from 2 to 30 whales or more in many cases. In some circumstances, such as during mating season or in areas where large supplies of food are abundant, thousands of whales may gather together to mate and forage, separating back to their smaller pod once they’ve finished participating in an event.

Source: Whale Facts