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Hawaiian Monk Seal (Neomonachus schauinslandi)

Status | Species Description | Habitat | Distribution | Population Trends | Threats | Conservation Efforts | Regulatory Overview | Taxonomy | Key Documents | More Info


ESA Endangered - throughout its range
MMPA Depleted - throughout its range
CITES Appendix I - throughout its range

Hawaiian monk seals are one of NOAA Fisheries' Species in the Spotlight                          

Species Description

375-450 pounds (170-205 kg)
7.0-7.5 feet (2.1-2.3 m)
silvery-grey backs with lighter creamy coloration on their underside; newborns are black. They may also have light patches or red and green tinged coloration from attached algae.
25-30 years
fish, cephalopods, and crustaceans
monk seals breed and haul-out on sand, corals, and volcanic rock; they are often seen resting on beaches during the day

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 monk seal 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.

Females generally mature around age 5; 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. Newborns are black, and then molt near the end of their nursing period.

Nursing occurs for about 1 month, 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. 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.


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
Hawaiian monk seal critical habitat, which was recently revised in 2015 (80 FR 50925), has been designated  in waters of the main Hawaiian islands and northwestern islands. More information on Hawaiian monk seal critical habitat is available on our Pacific Islands Regional Office website.


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:

Smaller breeding sub-populations also occur on Necker Island and Nihoa Island. Monk seals have been observed at Gardner Pinnacles and Maro Reef.

Most of the population is within the Papah?naumoku?kea Marine National Monument, which was designated in 2006.

A small but growing population of monk seals is also found on the Main Hawaiian Islands (MHI), where births have occurred on all 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 began. The most recent stock assessment reports with population estimates are available on our website.


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 This link is an external site.), 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 (over 1 million pounds) 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 This link is an external site..

We developed a video, "Good Neighbors: How to Share Hawaii's Beaches with Endangered Hawaiian Monk Seals," to enhance understanding of human-seal interactions and the direct impact that has on the population and recovery of the monk seal species:

link to Good Neighbors video
Video: How to Share Hawaii's Beaches with Endangered Monk Seals
Credit: NOAA Pacific Islands Regional Office

Regulatory Overview

Hawaiian Monk Seal Recovery Plan Signing Ceremony
Recovery Plan Signing
Photo: NOAA

Hawaiian Monk Seal in the water
Hawaiian Monk Seal
(Neomonachus schauinslandi)
Photo: NOAA Pacific Islands
Fisheries Science Center

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".

We first designated critical habitat [pdf] in May 1988 (53 FR 18988) and revised the designation in August 2015 (80 FR 50925). 

Hawaiian monk seals are also listed on Appendix I of the Convention on International Trade in Endangered Species (CITES).


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

Key Documents

(All documents are in PDF format.)
Title Federal Register Date
Spotlight Species 5-Year Action Plan n/a 01/25/2016
Main Hawaiian Island Monk Seal Management Plan   01/15/2016
Final Rule to revise critical habitat for Hawaiian monk seals 80 FR 50925 08/21/2015
Revised taxonomy and nomenclature for Hawaiian monk seals, effective 01/16/2015 79 FR 68371 11/17/2014
Programmatic Environmental Impact Statement (PEIS) for Recovery Actions 79 FR 20172 04/11/2014

Proposed revision to critical habitat for Hawaiian monk seals

» Extension of deadline for final Critical Habitat determination

76 FR 32026

77 FR 37867

12-month finding to revise Critical Habitat 74 FR 27988 06/12/2009
90-day finding on petition to revise Critical Habitat designation 73 FR 57583 10/03/2008
Recovery Plan (2007) 72 FR 46966 08/22/2007
» 1983 Recovery Plan 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
» 1986 Original Critical Habitat Designation 51 FR 16047 04/30/1986
ESA Listing Rule 41 FR 51611 11/23/1976
Stock Assessment Reports n/a various

More Information

Updated: February 10, 2016