The mating of Hawaiian monk seals usually occurs at sea and is rarely seen. This behaviour seems to occur to a far greater extent in those populations where there are more males than females. Not a great deal is known about the lifestyle of the Hawaiian monk seal outside the breeding season, but they are known to be fairly solitary. Their prey is known to include octopus, lobster and fish, including eels and flatfish, and they often feed along the slopes of coral reefs at depths of up to 75-90m. Hawaiian monk seals do not migrate, but there is a limited exchange of individuals between colonies.
Sharks are their main predators.
Statistics Adult Hawaiian monk seals weigh 180-270kg and the females are thought to be slightly larger than the males. Pups are born weighing about 11-15kg and measuring about 1m in length. Hawaiian monk seals have been known to dive to depths of 500m or more. Females give birth for the first time at 5-10 years of age. The maximum age for the species is 25-30 years, but few seals live that long.