Hawaiian Monk Seal (Monachus schauinslandi)
Status | Taxonomy | Species Description | Habitat | Distribution |Population Trends | Threats | Conservation Efforts | Regulatory Overview |
Key Documents | More Info
 Hawaiian Monk Seal (Monachus schauinslandi) Photo: NMFS Pacific Islands Fisheries Science Center  Hawaiian Monk Seal (Monachus schauinslandi) Photo: NMFS Pacific Islands Fisheries Science Center | |
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Did You Know? · Monk seals are named for the folds of skin on their head that look like a monk's hood and because it spends most of it's time alone or in small groups. |
Status
ESA Endangered - throughout its range
MMPA Depleted - throughout its range
Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Phocidae
Genus: Monachus
Species: schauinslandi
Species Description
The Hawaiian monk seal is one of the rarest marine mammals in the world. Part of the "true seal" family, Phocidae, they are one of only two remaining monk seal species; the other is the Mediterranean monk seal. A third species, the Caribbean monk seal, is extinct. Isolated from their closest relative 15 million years ago, Hawaiian monk seals are considered a "living fossil" because of their distinct evolutionary lineage.
Monk seal females are slightly larger than males, with females reaching 7.5 feet (2.3 m) in length and 450 lbs (205 kg) and males reaching 7 feet (2.1 m) in length and 375 lbs (170 kg). Adults have silvery-grey colored backs with lighter creamy coloration on their underside. Additional light patches and red and green tinged coloration from attached algae are common. The back of the animals may become darker with age, especially in males. Their life expectancy is 25-30 years.
Females generally mature at age 5-6 and it is unknown when males mature. Monk seals are promiscuous and mate underwater. Given male-dominated sex ratios at some breeding colonies, group mobbing of "estrus" females is known to occur, sometimes causing serious injury or even death to the female. The gestation period is 10-11 months. Birthing rates vary with a range of 30-70% of adult females birthing in a given year. While most births occur in late March and early April, birthing has been recorded year round. Pups are about 3 feet (1 m) and 35 lbs (16 kg) at birth. Newborns are black and then molt near the end of their nursing period. Nursing occurs for about 39 days, during which time the mother fasts and remains on land. After this period, the mother abandons her pup and returns to sea. Although they are generally solitary animals, females have been observed fostering others' offspring.
Monk seals are primarily "benthic" foragers, feeding on a variety of prey including fish, cephalopods and crustaceans. Their diet varies by location, sex, and age. Adults are generally nocturnal hunters while juveniles spend more time hunting species that hide in the sand or under rocks during the day. Monk seals generally hunt for food outside of the immediate shoreline areas in waters 60-300 feet (18-90 m) deep. Monk seals are also known to forage deeper than 1,000 feet (330 m), where they prey on eels and other benthic organisms. Tiger sharks and Galapagos sharks prey on monk seals.
 Hawaiian Monk Seal Critical Habitat (click for larger view PDF) |
Habitat
Monk seals live in warm subtropical waters and spend two-thirds of their time at sea. They use waters surrounding atolls, islands, and areas farther offshore on reefs and submerged banks. Monk seals are also found using deepwater coral beds as foraging habitat. When on land, monk seals breed and haul-out on sand, corals, and volcanic rock. Sandy, protected beaches surrounded by shallow waters are preferred when pupping. Monk seals are often seen resting on beaches during the day.
Critical habitat has been designated under the ESA to include all beach areas, sand spits and islets, including all beach vegetation to its deepest extent inland, and lagoon waters out to a depth of 20 fathoms in designated areas of use. On June 12, 2009, NOAA Fisheries announced its intention to revise the Hawaiian monk seal's critical habitat and is soliciting public comments.
 Hawaiian Monk Seal Range Map (click for larger view PDF) |
Distribution
The Hawaiian monk seal's entire range is within U.S. waters. The majority of monk seals live in six main breeding subpopulations in the Northwestern Hawaiian Islands (NWHI) at:
- Kure Atoll
- Midway Islands
- Pearl and Hermes Reef
- Lisianski Island
- Laysan Island
- French Frigate Shoals
Smaller breeding sub-populations also occur on Necker Island and Nihoa Island, and monk seals have been observed at Gardner Pinnacles and Maro Reef. Most of the population is within the Papahānaumokuākea Marine National Monument (http://hawaiireef.noaa.gov/), designated in 2006. Monk seals are now also found on the main Hawaiian Islands (MHI) where births have occurred on many of the major islands.
Population Trends
Hunted to the brink of extinction in the late 19th century, Hawaiian monk seals have been declining since modern surveying. The monk seal population is currently declining at 4% annually and is estimated at fewer than 1,200 individuals. Biologists predict this number will dip below 1,000 in the next 3-4 years, placing this species among the world's most endangered. While the larger NWHI population is shrinking, the MHI population is growing, with a population estimated at over 100 animals.
- Food limitations in NWHI, especially for juveniles and sub-adults
- Entanglement in marine debris
- Human interactions (especially in the MHI) including bycatch in fishing gear, mother-pup disturbance on beaches, and exposure to disease
- Loss of haul-out and pupping beaches due to erosion in NWHI
- Disease outbreaks
- Male aggression towards females
- Low genetic diversity
 Recovery Plan Signing Photo: NOAA |
Conservation Efforts
NOAA Fisheries and partners are implementing the Recovery Plan [pdf] for the Hawaiian Monk Seal.
Research investigating resource availability, foraging behavior (including use of crittercam 
), reproduction, and disease will help scientists and resource managers make better decisions.
Public education campaigns, including projects to reduce monk seal-human interactions on the MHI, are building awareness about conserving the species and habitat.
Volunteer groups are being expanded to help rescue and rehabilitate animals and prevent undue stress by keeping beachgoers away from resting animals. Direct efforts to disentangle seals and remove debris from haul-out sites have led to the removal of 492 metric tons of marine debris in NWHI since 1996, reducing injuries and death due to entanglement and digestion of marine debris.
The Hawaiian monk seal is listed as "endangered" in the IUCN Red List of Threatened Species .
Regulatory Overview
In 1976, the Hawaiian monk seal was listed as endangered under the Endangered Species Act.
Under the MMPA, Hawaiian monk seals are classified as "strategic stocks" and are considered "depleted".
NMFS designated critical habitat [pdf] in 1988 (53 FR 18988, May 26, 1988) that includes all beach areas, sand spits and islets, including all beach vegetation to its deepest extent inland, and lagoon waters out to a depth of 20 fathoms for the following areas:
- Kure Atoll
- Midway Islands, except Sand Island and its harbor
- Pearl and Hermes Reef
- Lisianski Island
- Laysan Island
- Maro Reef
- Gardner Pinnacles
- French Frigate Shoals
- Necker Island
- Nihoa Island
On June 12, 2009, NOAA Fisheries announced that it intends to revise the Hawaiian monk seal's critical habitat.
Hawaiian monk seals are also listed on Appendix I of the Convention on International Trade in Endangered Species (CITES).
Key Documents
(All documents are in PDF format.)
| Title | Federal Register | Date |
|---|---|---|
| NMFS "12-month finding" to Revise Critical Habitat | 74 FR 27988 | 06/12/2009 |
| Possible Revisions to Critical Habitat Designation | 73 FR 57583 | 10/03/2008 |
| Recovery Plan (2007) | 72 FR 46966 | 08/22/2007 |
| n/a | 03/24/1983 | |
| Response to Comments on 2007 Recovery Plan | 72 FR 46966 | 08/22/2007 |
| 5-Year Review | 72 FR 46966 | 08/22/2007 |
| Critical Habitat Designation (1988 Revised) | 53 FR 18988 | 05/26/1988 |
| 51 FR 16047 | 04/30/1986 | |
| ESA Listing Rule | 41 FR 51611 | 11/23/1976 |
| Stock Assessment Reports | n/a | various |
- FAQs about the Hawaiian Monk Seal "Hō'ailona" (a.k.a. "KP2")
- NMFS Pacific Islands Fisheries Science Center (PIFSC) Species Information
- NOAA's National Marine Sanctuaries
- NOAA Ocean Explorer
- NOAA Magazine: NOAA Signs New Hawaiian Monk Seal Recovery Plan
- Marine Mammal Commission Species Information
- U.S. Fish & Wildlife Service Hawaiian Monk Seal Species Profile
- Monachus Guardian Hawaiian Monk Seal Fact Files
