Hawaiian Monk Seal Breeding

The female Hawaiian Monk Seal reaches sexual maturity from age five to nine, and mating occurs in the water but has rarely been observed by humans. The gestation period is thought to be about 11 months, with most pups born between February and July. Preferred birthing sites are gently sloping beaches with adjoining shallow water providing ease of movement and protection from sharks. The majority of Hawaiian Monk Seals live in six main breeding subpopulations in Papahānaumokuākea at Kure Atoll, Midway Islands, Pearl and Hermes Reef, Lisianski Island, Laysan Island, and French Frigate Shoals.

At birth, the pup is jet black in color, approximately 3 feet long and weighs between 30 and 35 pounds. Newborn pups, feed only on mother’s milk from birth to about six weeks of age. Seal milk is very rich which allows pups to gain weight rapidly, more than quadrupling their initial weight before weaning. Nursing mothers are constantly at her pup’s side, and do not usually eat during this six-week period losing a tremendous amount of weight. A pup usually begins swimming with its mother from day one. After the six-week nursing period, the mother weans the pup abruptly, abandoning it to resume her own feeding. The weanling pup will generally remain at its birth beach for a month or two, and will slowly begin to range farther out to sea and eventually learn to feed on its own.

Eels, lobsters, octopi, and small reef and bottom fish are prey for the Hawaiian Monk Seal. Most of their feeding occurs at depths between 50 and 300 feet, with dive lengths averaging 10 to 15 minutes. The full lifespan of the Hawaiian Monk Seal is believed to be in the range of 25 to 30 years.