The Hawaiian monk seal, known scientifically as Neomonachus schauinslandi, is the only seal native to Hawaii. This is an endangered species of earless seals, and its survival is conservation reliant. Recovery efforts over the last decade have slowed the decline in population, but they remain one of the most endangered species on Earth.
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Characteristics & Appearance
Weight & Length
An adult Hawaiian monk seal typically weighs around 400 to 500 pounds, with some as large as 600 pounds. Females tend to be larger than the males. These marine mammals are typically 7 to 7.5 feet in length from crown to tail. They are often identified by unique features like their short front flippers and distinctive ear holes.
Physical Characteristics & Color
Most Hawaiian monk seal pups are born black, but adults are generally a dark grey or brown on their back and a lighter grey on their stomachs. This species molts roughly once a year, shedding their outermost layer. The “catastrophic molt” takes about 10 days to complete on-shore.
Coloring may also change based on environmental factors – for example, some that spend a lot of time foraging underwater will develop a green tint from algae.
To tell individuals apart, conservationists usually look to unique natural markings on the seals. Many feature recognizable scars or bleach marks that make it easy to identify them. NOAA officials have also used flipper tags to monitor individual seals over long periods of time.
The Hawaiian monk seal is one of two monk seal species. The other is the Mediterranean monk seal. A third species, the Caribbean monk seal, is now extinct.
Lifespan & Reproduction
The Hawaiian monk seal can live for over 30 years, although most live between 25 and 30 years.
They mate in the water to reproduce. Females typically mature and begin reproducing around 5 or 6 years of age. Their gestation period lasts 10 to 11 months, and they give birth on land. Many give birth during March and April, although births can occur year-round.
After birth, pups stay with their mother for four to six weeks. After that, most live a solitary life, which is part of why they are called “monks”.
Habitat
Where does the Hawaiian monk seal live?
The Hawaiian monk seal is one of two mammals that are native to Hawaii. This species is also endemic to Hawaii, meaning that they are only found in this region. Ancient Hawaiians called them ‘llio holo I ka uaua, which means “dog that runs in rough water”.
Most live by the Northwestern Hawaiian islands, although they can be found along the entire archipelago of the main Hawaiian islands.
They spend two-thirds of their life at sea, and they prefer warm, subtropical waters. Hawaiian monk seals live around small islands and atolls that are typically not populated by humans, and they often prefer areas further offshore on reefs and submerged banks. Hawaiian monk seals use the abundant coral reefs in their Hawaiian habitat to forage.
Hawaiian monk seals migrate onto sandy, empty beaches or volcanic rock shorelines for rest, shelter from storms, molting, and for giving birth to pups.
Food & Diet
What does the Hawaiian Monk Seal eat?
These marine mammals are carnivores, but they are generalists in what they eat, meaning they eat a wide variety of food depending on availability. They typically eat crustaceans like crabs, lobsters, and shrimps, cephalopods such as squid, octopus, eel, and other common fish in their habitat.
To find food, they usually travel away from the immediate shoreline, diving between 50 to 300 feet to forage. Monk seals can dive as far as 1800 feet, and sometimes forage at depths over 1000 feet. Adults are generally nocturnal hunters.
Threats & Predators
The Hawiian monk seal population face various threats to survival. Among these threats are predators, humans and climate change.
Human Threats
Hunting caused a major decline in the species up through the late 19th century. Today, human threats still exist for these beautiful creatures despite their protected status. There have been some cases of intentional killings, even some involving gunshot wounds in the last 10 years. Human activity like feeding and other disturbances can also affect their livelihood.
Climate Change & Global Warming
One main threat to monk seals is food availability – many juveniles struggle to find food to survive. Maternal separation contributes to this, as seal pups often fail to provide for themselves early on. Changes in their ecosystem due to factors like climate change may also affect food availability. Habitat loss and rising sea levels also pose a threat to these animals.
Other threats to monk seals include entanglement. Entanglement is a common issue for Hawaiian monk seals, with pollution like marine equipment, fishing nets, hooks and other fishing gear accumulating in their habitats.
Predators
Shark predation is a common threat amongst monk seals. Many species of sharks including tiger sharks, gray reef and white-tipped reef sharks, great white sharks, and Galapagos sharks hunt Hawaiian monk seals.
Other Threats
There have also been significant cases of adult monk seals male aggression towards females or pups.
Conservation Status
Hawaiian monk seals are one of the most endangered seal species in the world. Experts estimate that there are about 1,400 surviving today. They are a protected species under the Endangered Species Act, the Marine Mammal Protection Act, and Hawai’i state law.
They are considered Critically Endangered. Conversation efforts have managed to improve their population status, but they still remain endangered.
Fun Facts About Hawaiian Monk Seals
- They are the state mammal of Hawai’i.
- This species can hold their breath for up to 20 minutes, allowing them to dive to impressive depths to forage for food.
- Roughly 30% of the current population is a direct result of recovery and conservation efforts
- Up to 10 seals may be found on the Big Island at any time – but they should be given at least 150 feet of space from humans for both the seals and human safety.
- The Hawaiian monk seal is the rarest seal or sea lion found in US waters
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