The Hawaiian monk seal, Neomanachus schauinslandi, is one of the most endangered marine mammals in the world and the most rare of the pinniped family (seals, sea lions and walrus) in the western hemisphere. It is believed that the animal is named “monk” seal due to its solitary lifestyle as well as folds of skin on its neck that some believe resemble a priest’s cowl. These animals can live in the range of 30-35 years (usually less in the wild) and spend about 1/3 of their time on land. They are benthic foragers and have been observed swimming at depths greater than 1,800 feet though their normal range of activity is less than about 300 feet. They can stay under water for up to 20 minutes and divers report seeing them napping under water. Adult animals are 6 to 8 feet long and can weigh between 350 and 500 pounds or more.
The Hawaiian monk seal is the only tropical seal species left in the world and only lives in Hawaiian waters. Its closest relative, the Caribbean monk seal is extinct. Living in Hawaiian waters for millions of years, before some of the islands were even fully formed, these animals were undisturbed for thousands of generations before human settlers in the middle ages and seal hunters in the 19th century hunted and killed these animals to near extinction. Later, in the 20th century their numbers were further impacted by the build-up of human presence, environmental damage, and ecosystem changes within the Hawaiian archipelago. In 2016 there were only about 1,400 of these animals left in the world, about 1,100 of which live around uninhabited islets and atolls in the northwestern Hawaiian island chain, with only about 300 animals living around the main populated Hawaiian Islands of Niihau, Kauai, Oahu, Molokai, Maui, Lanai, Kahoolawe and Hawaii Island.
The small but stable population of animals living around the main Hawaiian Islands provides an important hope for the survival and ultimate recovery of the Hawaiian monk seal species but these animals are threatened by fishery interactions (hookings, entanglement in nets, etc.), human-caused trauma and toxoplasmosis (a disease carried by feral cats).
This iconic and charismatic species, called “a living fossil” by scientists, has suffered these dramatic population losses and the threats of extinction due to impacts largely caused by one species – man. And it is up to one species – man, to help the Hawaiian monk seal survive and recover.
The Hawaiian monk seal is an apex predator and a sentinel species. Its beach is our beach. Its waters are our waters. It eats some of the same food we eat. As a sentinel species, the fate of the Hawaiian monk seal may foretell our own. Its success is our success.
Did you know …
- The Hawaiian monk seal (Neomonachus schauinslandi) is one of the most endangered animal species in the world. Only about 1,400 seals are left. About 1,100 of these animals live in the uninhabited Northwestern Hawaiian Islands and only about 300 live in the main islands of Niihau, Kauai, Oahu, Molokai, Maui, Lanai, Kahoolawe and Hawaii Island.
- The Hawaiian monk seal is one of the most rare marine mammals. Part of the “true seal” family (Phocidae), they are one of only two remaining monk seal species left on earth. The other is the Mediterranean monk seal. A third monk seal species – the Caribbean monk seal – is extinct.
- Isolated from their closest relative up to 15 million years ago, Hawaiian monk seals are considered a “living fossil” because of their distinct evolutionary lineage.
- The Hawaiian monk seal is one of only two mammals indigenous to Hawaii’s environment (the other is the hoary bat).
- Hawaiian monk seals are endemic to the Hawaiian Islands which means that they are native to Hawaii and are found nowhere else on earth. Hawaiian monk seals have evolved for millions of years in the waters and on the coastlines of Hawaii.
- The gestation period is about 11 months. Birthing rates vary with a range of 30-70% of adult females birthing in a given year. While most births occur between February and August, birthing has been recorded year round. Newborns are black, and then molt near the end of their nursing period.
- Nursing occurs for about 5 weeks, 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 (bottom feeders), and eat a variety of prey including fish, cephalopods, and crustaceans. Monk seals generally hunt for food outside of the immediate shoreline areas in waters 60-300 feet (18-90 m) deep but they have been observed swimming at depths greater than 1,800 feet, where they prey on eels and other benthic organisms.
- Monk seals living in the main Hawaiian Islands are threatened by several natural and human-related activities including fishery interactions, diseases and human attacks. In the Northwestern Hawaiian Islands, there are additional and different threats to their population recovery.
- Monk seals are named for the folds of skin on their head that look like a monk’s hood and because they spend most of their time alone.
- The Hawaiian monk seal is Hawaii’s official state mammal.
- Females generally mature around age 5; it is unknown when males mature. Monk seals are promiscuous and mate underwater. They give birth on land.
- In the main Hawaiian islands, the youngest females to give birth are 4-5 years old while in the Northwestern Hawaiian Islands, females may start to give birth when older.
- These animals can live up to 30-35 years, but few seals live this long in the wild.
- Hawaiian monk seals usually dive for an average of 5-10 minutes when feeding; but they can hold their breath as long as 20 minutes.
- Monk seals usually rest and sleep on the beaches of the Hawaiian Islands, sometimes for days at a time. Divers can occasionally see these seals sleeping underwater as well.
- Individual seals often frequent the same beaches over and over, but do not defend regular territories.
- Hawaiian monk seals do not live in colonies like sea lions or elephant seals. They are mostly solitary but sometimes may be seen lying near each other in small groups but usually not touching.
Read NOAA’s new Hawaiian monk seal natural history brochure – DOWNLOAD