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Hawaiian Monk Seal (Monachus schauinslandi)

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Monk Seal / thievingjoker, Flickr

A Hawaiian monk seal rests on Ke'e Beach, located on Kaua'i.

Courtesy thievingjoker, Flickr

The Hawaiian monk seal (Monachus schauinslandi) is one of the most endangered marine mammals in the world. This is one of three species of monk seal, which also includes the Mediterranean (also critically endangered) and the Caribbean, which is now extinct - sadly, the last record of a live Caribbean monk seal was in 1952.

Monk seals get their name from the folds of skin on their head that resemble a monk's hood. They are also relatively solitary animals. The Hawaiian name for this seal is ‘Ilio holo I ka uaua - "dog that runs in rough water".

Description:

Adult Hawaiian monk seals have silvery-gray backs with lighter undersides. Their backs may contain lighter patches with red or green coloration from algae. Newborn seals are black. As the seals age, their fur becomes darker in coloration.

Hawaiian monk seals are 7-7.5 feet long and weigh up to about 450 pounds. Females are slightly larger than males.

Classification:

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Carnivora
  • Family: Phocidae
  • Genus: Monachus
  • Species: schauinslandi

Habitat and Distribution:

Hawaiian monk seals spend two-thirds of their lives at sea, but haul-out on land to rest, give birth and nurse. They live in warm waters, often around atolls, islands and reefs.

All Hawaiian monk seals live within U.S. waters, in 6 main breeding subpopulations. These are located in the Northwestern Hawaiian Islands at Kure Atoll, Midway Islands, Pearl and Hermes Reef, Lisianski Island, Laysan Island, and the French Frigate Shoals. There are smaller breeding populations throughout this region and they have also been found on the main Hawaiian Islands.

These seals do not migrate and usually live near the place where they were born, although occasionally some travel long distances to other sites in the Hawaiian Islands.

Feeding:

Hawaiian monk seals feed on fish, cephalopods, and crustaceans, in waters 60-300 feet deep. They may also forage in deeper waters over 1,000 feet. Adults mainly feed at night while juveniles mainly feed during the day.

Reproduction:

Females are mature at 5-6 years of age, but the maturity age of males is unknown. Monk seals mate underwater. Breeding colonies may be dominated by males, leading to competition for and mobbing of females. After mating, females give birth (usually on sandy beaches surrounded by shallow waters) after a 10-11 month gestation period. Pups are usually born in the spring, and are 35 pounds at birth. They nurse for about 39 days. The mother remains on land with her pup during this time. But after weaning, the mother returns to the ocean and the pup is left on its own.

The lifespan of the Hawaiian monk seal is thought to be 25-30 years.

Conservation:

Hawaiian monk seals are listed as critically endangered on the IUCN Red List due to their relatively small poulation size, continuing population declines and "continuing threats from a variety of sources."

Hawaiian monk seals acheived their precarious population status due to hunting. The current population is estimated at 1,060 seals (Source: NOAA Estimate) and the number of seals in the Northwestern Islands is declining, but those in the main Hawaiian Islands have been increasing. The species is protected under the Endangered Species Act, but there are many current threats. These include food limitations, entanglement in marine debris, bycatch in fishing gear, human disturbance (on beaches), loss of habitat, disease, low genetic diversity and aggression of males toward females.

Monk seal predators include tiger sharks and Galapagos sharks.

What Is Being Done to Help the Monk Seal?

Work is being done to help this species before it goes extinct. This includes studies on Hawaiian monk seal population and behavior, removal of marine debris from habitat, designating Hawaiian monk seal habitat as critical habitat, conducting education to minimize human disturbance of seals on beaches, moving males to different breeding colonies to improve male-female sex ratios, and regulations on fisheries.

References and Further Reading:

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