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Hawaiian Monk Seals

Scientific name: Monachus schauinslandi

Hawaiian monk seals, ili-holo-i-ka-uaua (translated as "the dog that runs in the rough seas"), are native to and found only in the Hawaiian Islands. Sometimes called "living fossils," monk seals haven't changed in 15 million years. They are named for their solitary behavior and the folds of skin on their neck, which resemble a monk's hood.

Hawaiian monk seals grow to be seven-feet long and can weigh up to 600 pounds. Females tend to be larger than males. Monk seals are true seals, as opposed to fur seals or sea lions, since they have no external ears and use their hind flippers for propulsion and front flippers as stabilizers. Unlike the ‘eared seals’ they cannot ‘sit up’ on their front flippers.

Population Status

Hawaiian monk seals are one of the most endangered ocean animals in the world, with approximately 1,200 seals remaining.  It is believed that Hawaiian monk seals may have declined by 66% from 1958 to 2006.  Scientists predict that in the next five years the population could dip below 1,000 animals. 

Early declines in the population are attributed in part to disturbance of monk seals in their Northwestern Hawaiian island habitat during World War II.  We have very little historic information about how many monk seals there were before WWII.  At the time of the first counts, in the 1950s, there were likely around 3,000 individuals. However, the pre-war population size is likely to have been greater.

Habitat & Diet

Hawaiian monk seals live entirely within U.S. waters, with the majority of the population found in the remote Northwestern Hawaiian Islands of the Pacific Ocean. There are six main breeding groups, located at Kure Atoll, Midway Islands, Pearl and Hermes Reef, Lisianski Island, Laysan Island, and French Frigate Shoals. Monk seal critical habitat has been designated for these islands as well as at Maro Reef, Gardner Pinnacles, Necker Island, and Nihoa Island. There is a small but viable, and growing, population in the main Hawaiian Islands, and Ocean Conservancy is advocating for the expansion of critical habitat to include key beaches and foraging areas in the main Hawaiian Islands.

Little is known about monk seal habits and distribution in waters far from Hawaii’s shores, although studies show they can dive to depths of up to 500 meters (1,640 feet) searching for food on the sea floor. They have a very diverse diet, consisting of fish and eels, octopus, squid, and lobster. Video footage of feeding seals show them possibly competing with jacks (ulua) and sharks for food. Availability of food seems to be a limiting factor in the Northwestern Hawaiian Islands, affecting body condition and survival of the younger seals that have not yet reached breeding maturity. The few young monk seals found in the Main Hawaiian Islands are generally in better condition.

Threats to Hawaiian Monk Seals

In 1976, the Hawaiian monk seal was listed as endangered under the federal Endangered Species Act. Despite the fact that the seals live in remote locations, seal hunting in the 19th and early 20th centuries devastated the population. Monk seals also have a high sensitivity to human interactions, direct and indirect. U.S. military operations in the Hawaiian Islands prior to the 1990's disturbed the seals and hampered their ability to reproduce.

Today, most of the islands inhabited by monk seals are protected as part of the Papahānaumokuākea Marine National Monument.  An executive order signed by President Clinton in 2000 designated the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve, and then in June 2006, President George W. Bush declared the Northwestern Hawaiian Islands a Marine National Monument. The designation of this massive coral reef system as a national monument will help to minimize human disturbance where monk seals feed and reproduce, and should help to rebuild depleted reef fish and lobster populations, while allowing critical, low-impact research on monk seals to continue.

Due to ocean currents converging near the Northwestern Hawaiian Islands, marine debris -- floating trash and discarded or lost fishing nets-- from thousands of miles away is deposited there, creating a significant threat to the monk seals' recovery. In the past 20 years, more than 200 monk seals have been observed entangled in fishing gear or other trash. El Niño events have been associated with higher than average levels of entanglement in trash and fishing nets, caused by changes in wind and currents that concentrate marine debris in the Northwestern Hawaiian Islands.

Rising ocean temperature and the melting of ice caps caused by global climate change is predicted to increase sea level in the Northwestern Hawaiian Islands, resulting in erosion and the potential for significant loss of critical habitat. Monk seals depend on access to beaches for pupping, nursing, molting, and resting.  Habitat loss on land due to storm activity and increasing sea level rise may be intensified in the future, with low lying islands in French Frigate Shoals and Pearl and Hermes Reef expected to be hardest hit. Warming oceans may bring an increased risk of bleaching and disease to local coral reefs and other critical habitats, which provide protection of beach habitats. Warming oceans are also contributing to ocean desertification, with huge expanses of low productivity affecting food availability.

Food availability, mobbing (aggressive behavior by males), and shark predation are contributing to low survival rates of females and young seals. The highest priority for recovery of monk seals is to improve the survivorship of females, especially juveniles, in the Northwestern Hawaiian Islands. To achieve this goal, increased efforts are needed to protect monk seal critical habitat and its food supply, target research to better understand factors associated with survival of young seals, protect females and young seals from mobbing and shark predation, remove marine debris, and prevent lethal entanglements.

A growing number of seals in the Main Hawaiian Islands holds the promise for recovery of the species. Population levels may be as high as 100 seals, but seals are threatened by human disturbance of mothers and pups in areas where they haul out onto land, entanglement in recreational fishing gear, and exposure to human and domestic animal diseases. Increased outreach to local communities about the plight of monk seals is needed, as well as the designation of critical habitat in the main Hawaiian Islands and better coordination between local, state, and federal governments, scientists and non-governmental organizations.

To boost survival rates, the National Marine Fisheries Service and local animal care organizations launched a pilot captive care program for monk seals. Seals from the Northwestern Hawaiian Islands were brought to facilities in Oahu to receive extra care and feeding before being re-released into the wild where they were first captured. Satellite tags placed on released seals show these seals are doing well, diving and feeding.

What Ocean Conservancy is Doing to Help

On July 2, 2008, Ocean Conservancy petitioned the National Marine Fisheries Service, to expand critical habitat for Hawaiian monk seals to the Main Hawaiian Islands to the recovery of the species. On June 12, 2009, the National Marine Fisheries Service stated that they intend to revise critical habitat and provided some initial thoughts on the criteria they will use in making the final designation, which they indicate will occur through future rulemaking.

To address marine debris impacts on monk seals, we continue to actively engage people to remove trash and debris from the world’s beaches and waterways, to identify the sources of debris, and to change the behaviors that cause pollution through our International Coastal Cleanup (ICC) (see our 2007 ICC Annual Report).

What You Can Do to Help

• Sign up or start up a beach clean-up with International Coastal Cleanup (ICC).
• Take Action and join the Ocean Action Network by receiving email alerts on future action pertaining to the Hawaiian monk seal.

For More Information

• Monk Seal Recovery Plan (2007): http://www.nmfs.noaa.gov/pr/pdfs/recovery/hawaiianmonkseal.pdf
• National Marine Fisheries Service, Pacific Islands Fisheries Science Center Hawaiian Monk Seal Research Program: http://www.pifsc.noaa.gov/psd/mmrp/monkseals.php
• Papahānaumokuākea Marine National Monument: http://www.hawaiireef.noaa.gov/
• Critical Habitat Finding: http://www.fpir.noaa.gov/Library/PRD/Critical%20Habitat/HMS_12-month_finding_6-12-09.pdf

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The Ocean Conservancy, International Coastal Cleanup and Ocean Action Network are registered trademarks of Ocean Conservancy.

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The Ocean Conservancy, International Coastal Cleanup and Ocean Action Network are registered trademarks of Ocean Conservancy.

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