Pacific Islands Fish and Wildlife Office
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Endangered Species in the Pacific Islands

Hawaiian Monk Seal / Monachus schauinslandi / ‘Ilio holo I ka uaua (dog that runs in rough water)

Photo of monk seal and pup An adult monk seal is usually dark gray or brown with a light gray or yellow belly. Adults can weigh anywhere from 375 to 500 pounds; adult females are generally larger than males. Pups are jet black and usually weigh 25 to 30 pounds at birth and weigh up to 132 to 198 pounds within five to six weeks.

The monk seal's common name is derived from its folds of skin that look like a monk's hood, and because it spends most of its time alone or in very small groups.
Monk seal and pup - Photo credit USFWS

Habitat & Behavior:
Endemic to the Hawaiian archepelago and found mostly in the Northwestern Hawaiian Islands (Nihoa Island to Kure Atoll). Increasing sightings reported from main Hawaiian Islands (Island of Hawaii to Niihau). These atolls and islands are very remote and are either uninhabited or have little impact by humans, thus providing an ideal habitat for these easily disturbed creatures.

The coral reefs found around these atolls and islands provide the monk seal with its food supply: lobster, eels, small octopus, and reef fishes. Their enemies include humans, sharks, diseases, attacks from their own species, and marine debris such as lost fishing nets and plastic products.

Mothers stay with their pups from birth to about five or six weeks, never leaving them unprotected to go feed. During this time, she will lose as much as 300 pounds in weight. When she finally departs, the pup is on its own to learn to catch food.

They spend most of their time in the ocean but like to rest on sandy beaches, and sometimes use beach vegetation as shelter from wind and rain. Monk seals are expert swimmers and divers; one seal was recorded diving into depths in the range of 66 and 96 fathoms (396 to 576 feet). The average monk seal dives 51.2 times per day. The life span of the Hawaiian monk seal is from 25-30 years.

Past & Present:
Hawaiian monk seals were first recorded in 1825 at the Hawaiian archipelago's northernmost island, Kure Atoll. Scientist estimate about 1,100 to 1,200 monk seals live in the Hawaiian islands chain today. The abundance of Hawaiian monk seals in the Northwestern Hawaiian Islands (NWHI) is declining about 4% per year. Analyses indicate that juveniles are failing to thrive, and only about one of every five juvenile monk seals live to reach maturity. The population decline will continue indefinitely unless survival of juvenile monk seals improves.

Factors which threathen the persistence and recovery of monk seal populations include food limitation, competition with fisheries, cceanographic change, competition with other predators, entanglement, shark predation, and infectious disease. Although not directly responsible for monk seal mortality, human activities on beaches, even at low levels, can cause monk seals to abandon haul-out areas. Such disturbance is particularly disruptive to mother-pup pairs.

In the 1800s, shipwrecked crews ate them in order to survive. By the early 1900s, humans were developing commercial and military facilities in monk seal habitat. Bottomfish, longline, and lobster fisheries have all directly affected monk seals. Indirectly, fisheries may affect seals through competition for prey or entanglement in fisheries debris, such as lost or discarded net and line.

Conservation Efforts:
The Hawaiian monk seal recovery efforts are overseen by the National Marine Fisheries Service, in cooperation with other government and private organizations and universities. The U.S. Fish and Wildlife Service manages many remote islands as refuges to protect their habitat.

Extensive efforts have been made to protect important habitat, reduce disturbance on key breeding beaches and islands, reduce the impact of entanglement, reduce extraordinary mortality caused by male aggression and by shark predation, and understand how active intervention can improve the survivorship of pups.

The Hawaiian monk seal was listed as an endangered species in 1976 under the Federal Endangered Species Act. Critical habitat was designated in 1988 from beaches to a depth of 20 fathoms (120 feet) around the northwestern Hawaiian islands.

 

Last updated: September 20, 2012
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