They suck sediment and prey from the sea floor by rolling on their sides and swimming slowly along sucking sediment and prey from the sea floor. Gray whales are probably old enough to mate around 8 years old. Females are pregnant for about 13 months approximately every two to four years. Calves are born able to swim and are known to double their weight in about three months, and double their length in about two years. A mother and calf form a very close attachment, with the calf spending the majority of its time swimming close to its mother.
Gray whales do die of natural causes and are sometimes preyed upon by killer whales .
Pods of killer whales have been known to attack gray whales throughout their range, especially young animals during migration. Today, indigenous hunters practice subsistence whaling on a small-scale. Gray whales may also be harmed by pollution, ship strikes, or entanglement in fishing gear. Books and the world wide web are excellent places to learn more about marine mammals. Books Leatherwood, Stephen.