A global open water diver
Sei whales are pelagic, occurring far from shore in temperate oceanic waters worldwide.
Social StructureAlthough sei whale groups mostly consist of two to five individuals, thousands may aggregate where plenty of food is available.
Life Cycle
Sei whales become sexually mature between 6 to 8 years old. Sei whales can live for 65 year.
Breeding
Mating season ranges from November to February in the Northern Hemisphere and from May to July in the Southern Hemisphere. Females generally give birth to a single calf every other year in winter, after a gestation period of 10.5-12 months.
Although we know very little about their breeding habits, some data indicate that sei whale migration is loosely organized around sex, age, or reproductive function. This presumably relates to mating strategies, but at this time nothing is known of their mating habits or calving grounds.
Diet
Like other baleen whales, sei whales feed by skimming and swallowing surface plankton, mainly copepods (tiny marine crustaceans) but also euphausiids (krill - shrimp-like crustaceans).