Distribution in Texas.
Blue whales occur in all oceans of the world.
Both of these identifications have been questioned, however, and the occurrence of the blue whale in the Gulf of Mexico is problematical. Spring and summer finds northern hemisphere blue whales migrating northward to arctic feeding grounds. In fall and winter the whales move back to temperate waters where mating and parturition take place. This trend is also exhibited by southern hemisphere blue whales although feeding grounds are in the Antarctic. As the seasons are reversed between the two hemispheres, northern and southern blue whales do not interbreed in temperate and equatorial waters.