Hawaiian monk seal (Monachus schauinslandi)

Description

Adults dark gray to brown above, light gray to yellow below. Adult body length: 7-8 ft. Weight: 375-500 lbs (167-222 kgs ). Adult females generally larger than males. Pups jet black and weighs 25-30 lbs (11-14 kgs) at birth. 5-6 week nursing period. Coat is lost through molting once per year, usually between April and December. Molting takes approximately 7-10 days. Seals remain on shore during most of the molting period.

Distribution

Endemic to Hawaiian archepelago and found almost exclusively in Northwestern Hawaiian Islands (Nihoa Island to Kure Atoll). Occasional sightings reported from Main Hawaiian Islands (Big Island of Hawaii to Niihau). In 1998, about 1200-1300 in total population. About 65 individuals reside at Midway Atoll. Most seals remain at their birth atoll for life and there is little permanent inter-atoll movement. About 22 monk seals visit Midway intermittantly from Pearl and Hermes, and Kure Atoll. Monk seal population currently being studied by National Marine Fisheries Service researchers.

Feeding

Feeds on lobster, eels, small octopus, and reef fishes, usually feeds at depths of less than 50 m with a maximum of 500 m. Resting takes place on isolated and undisturbed beaches.

Breeding

Sexually mature at age 4-7 years. Females begin breeding at 5-6 years. Males bite the back of females while mating and can rip skin and blubber. Mating takes place in the water. Pregnant females will not give birth on beaches where there is much human activity. Most pups born between February and July. Fourteen and twelve pups were born on Midway in 2000 and 2001, respectively. Most sexually mature females give birth every other year.

A single seal pup is most often born between February and July on undisturbed beaches. Pups are continually attended by the mother for 4-6 weeks. Seal milk is very rich and a pup may triple in weight in six weeks, with the mother losing as much as 300 lbs (133 kilos).

Mortality

Primary predator is the tiger shark. Female seals also die from "mobbing", when as many as 20 adult males attempt to mate with one female on islands where there is a skewed sex ratio. Other causes of mortality include: marine debris entanglement, male aggression and prolonged separation of pup from mother during the nursing period.

Conservation

Monk seals haul out to rest or sleep and should not be disturbed. If you see a seal on the beach, do not approach closer than 100 ft (30 m). Increase distance if seal is aware of you. Decrease in human activity on beaches will encourage growth of Midway population.