Hawaiian Monk Seals (Monachus schauinslandi)

Hawaiian Name: ‘Ilio-holo-i-ka-uaua

Endemic

Status: Endangered Species.

What is 400 pounds (180 kg) and likes to lie on the beach all day, occasionally barking?  The monk seal of course.

[Illustration: Monk seal]

Male monk seals are about 7 feet (2.1 m) long and weigh more than 400 pounds (180 kg) at maturity.  Females may be up to 1 foot  (30 cm) longer and may weigh 600 pounds (272 kg) or more. 

Monk seals live to about 30 years of age, and will typically remain near the island on which they were born.  The Hawaiian name for the monk seal is ‘ilio-holo-i-ka-uaua, and means “quadruped running in the rough [seas].”[i] 

Hawaiian monk seals may dive up to 1,700 feet (213 m) deep in pursuit of invertebrates and sand-dwelling fish.  The monk seal is adept at turning over rocks and rooting around with its snout to uncover prey.  Monk seals eat octopi, spiny lobsters, and eels (but not moray or conger eels).  A monk seal may dive more than 50 times per day in search of food. 

Scientific research by the National Marine Fisheries Service and the National Geographic Society involved mounting (with epoxy) 4-pound (1.8-kg) cameras on the backs of monk seals.  The films revealed to the researchers a great deal of new information about monk seal feeding and behavior.

One seal-mounted camera revealed a monk seal eating a razor wrasse fish.  Another monk seal feasted on a triggerfish.  Other species (e.g., Galapagos sharks, schools of jacks) sometimes follow the seals, apparently waiting for sand-dwelling fish or invertebrates to be rustled up from the seafloor by the seals.  Sometimes the seals would nap in an underwater cave for about five minutes before swimming up for air and then diving back down to the cave, as deep as 250 feet (76 m), and then resuming their nap.

Gestation and Life Cycle

Monk seals mate in the water but give birth on land.  Breeding occurs mostly during spring and summer.  The period of gestation (the time between fertilization and birth) is about one year for monk seals. 

Birthing begins as early as mid-December, peaks from March to May, and may occur as late as mid-August.  For giving birth, the mother seals prefer sandy or coral rubble beaches with nearby vegetation that may provides shelter during the night. 

Hawaiian monk seals are completely black at birth, and weigh about 24 to 33 pounds (11 to 15 kg).  Eventually they turn more of a creamy white color on their belly, and silvery gray on their back.  The infant monk seal looks like a large football with whiskers and floppy flippers. 

The mother seal nurses the infant for about six weeks.  During this time the baby may grow from around 30 pounds (14 kg) to more than 180 pounds (82 kg).  The mother may lose more than 200 pounds (91 kg) during this time because she doesn’t eat during the nursing period, surviving totally upon her own stored blubber.

As monk seals become adults they develop a more brownish coat, called a pelage.  The seal’s underside may be yellowish in color, and their fur may sometimes become a greenish color (from algae).  Some seals may also be identified by distinctive patches of blond.

Monk seals shed their coat once each year, and this is known as epidermal molting.  As the seal sheds its whole epidermis along with all its hair, a shiny new coat underneath is revealed.  The only other seal that molts like this is the elephant seal.  Monk seals often “haul out” onto the beach during daytime hours to rest, and then feed at night.

Population and Habitat

Hawaiian monk seals were once hunted for their meat, oil, and skin, causing the species to approach extinction.  The population of Hawaiian monk seals has been stable overall since 1993, with estimates ranging from 1,200 to 1,500 animals. 

Hawaiian monk seals are still very endangered.  Since 1950, the monk seal population has declined more than 40%.  Researchers continue to try to halt the decline in the monk seal population. 

Almost all Hawaiian monk seals live near the Northwestern Hawaiian Islands, which are hundreds of miles northwest of Kaua‘i.  The monk seal population of the main Hawaiian Islands is much smaller than the Northwest Hawaiian Island population.  A 2001 aerial survey estimated that there were about 52 monk seals on the main Hawaiian Islands with at least 25 of those residing around Ni‘ihau.

Approximately 20 monk seals live around Kaua‘i, the Hawaiian Island closest to the monk seals’ main breeding areas on the Northwestern Hawaiian Islands.  In past years, some overly aggressive male monk seals known to harm monk seal infants have been relocated to the main Hawaiian Islands. 

The largest single monk seal population is at the Northwestern Hawaiian Island called French Frigate Shoals.  At French Frigate Shoals the number of monk seals declined by 50% between 1989 and 2000, to just 405 seals.  However, the monk seal population on some other small islands and atolls has grown.

Evolutionary History of Monk Seals

Considered the most primitive seal in the world, monk seals belong to the Order of marine mammals known as Pinnipeds, which means “fin-footed” and includes walruses, seals, and sea lions.  Monk seals are classified as “true seals,” meaning they are more awkward on land but more graceful in the water than “eared seals,” like the fur seal.

Scientists believe the ancestors of monk seals originated in the North Atlantic Ocean some 15 million years ago.  Then about 200,000 years ago, the Isthmus of Panama formed, permanently dividing the ancestors of what we now classify as Hawaiian monk seals from their cousins in the Mediterranean and the Caribbean. 

This led to three types of monk seals: Hawaiian, Caribbean, and Mediterranean monk seals, all in the family Phocidae and the genus Monachus, and the only tropical seal species. 

The Caribbean monk seal (Monachus tropicalis) is now extinct (since the 1950s), and the Mediterranean monk seal (Monachus monachus) is extremely endangered, with less than a few hundred left.

Newborn Pups in the Islands

In recent decades, monk seals sightings around the main Hawaiian Islands were relatively rare.  In the last decade, however, there have been numerous monk seal births on the beaches of the main Hawaiian Islands. 

In the predawn hours of July 6, 2000, when a 700-pound (318-kg) monk seal gave birth to a 25-pound (11-kg) pup at Po‘ipū Beach on Kaua‘i’s south shore.  When the jet-black little pup was just 22 hours old, its mother took it for its first swim. 

The mother was also observed to bark at the pup if it strayed too far from their resting area on the beach.  The beach park where the seal was born is one of the most popular on Kaua‘i, and significant efforts were taken to prevent human contact, which could cause the mother seal to abandon her pup.

 Local volunteers with the Kaua‘i Monk Seal Watch Program (www.kauaimonkseal.com), protected a perimeter around the pup, and maintained a 24-hour-a-day protective watch to make sure the mother and daughter were not disturbed. 

Another monk seal pup was born on Kaua‘i a few weeks later about 4 miles (6.4 km) east of Po‘ipū, at Māhā‘ulepū.  The pup at Po‘ipū was eventually weaned by her mother, and then taken by researchers to a remote north shore beach.  Later in the year the two young seal pups were seen together.

The monk seal that gave birth at Po‘ipū Beach, Kaua‘i in 2000 returned the next year and gave birth again on July 22, 2001 (researchers identified the mother by scars on her body). 

The healthy male pup weighed about 25 to 30 pounds (11 to 14 kg), and was the fifth documented birth on the main Hawaiian Islands in 2001.  In August of 2001 a monk seal was born near Anahola, Kaua‘i, and another was born on Kaua‘i’s north shore earlier in the year.

The Po‘ipū birthing area again led authorities to close off an area of the beach in order to provide a perimeter around the mother and pup so the seals were not disturbed. 

The mother monk seal nevertheless had several encounters with humans in the water at the popular beach, including causing minor injuries to one man when it bit him on the rear end.  The man was a visitor from Texas, and at the time of the incident he was snorkeling just outside of the prescribed protected area.

The incident was the first documented attack on a human by a monk seal protecting its pup, and occurred when the pup was just two weeks old.  The attack was probably a defensive behavior since the mother had recently been swimming nearshore with the pup. 

Authorities doubled the size of the closed-off area.  About two weeks after the man was nipped in the rear, the same mother lunged and barked at some other swimmers who were apparently coming too close to her pup. 

First Documented Big Island Monk Seal Birth

Monk seal births have also occurred on Kaua‘i’s north shore as well as Kaho‘olawe, Moloka‘i, and Hawai‘i Island.  On the second or third of May, 2001 a Hawaiian monk seal gave birth on a remote Ka‘ū beach on the island of Hawai‘i, and was the first ever documented monk seal birth on the island.

The pup weighed about 25 pounds (11 kg), and was nursed by its mother for about six weeks.  The mother’s general history was known because she had been tagged after she was born in 1992 at Midway Atoll.  In 1998 the seal went to Laysan Island and then two years later, to Moloka‘i. 

When the seal showed up on a Ka‘ū beach in April, 2000, officials from National Marine Fisheries had to remove a fishhook embedded in her tongue.  Then in May the seal gave birth.  At the time, the seal’s 1,400-mile (2,253 km) journey from Midway to the Big Island was longest documented migration of a Hawaiian monk seal.

The monk seal born on Hawai‘i Island (the first documented birth on the island) was marked with a flipper identification tag as RM-34.  Unfortunately, RM-34 had to be relocated when he was about 2½ years old after a series of incidents of interaction with humans.

RM-34’s first troubles occurred at Kealakekua Bay when the seal’s potentially dangerous interactions with humans led to its capture.  On October 20, 2003, the seal was fitted with a satellite transmitter to track its location, and then taken to the Ka Lae (South Point) area, near its birthplace.  The seal promptly returned to Kealakekua Bay, where more interactions with humans took place, so the seal was recaptured and taken to Kaho‘olawe.

About two weeks after being released in the waters of Kaho‘olawe, the 300-pound (136-kg), 7-foot (2-m) long monk seal showed up on Maui where it began interacting with several dozen people who petted and posed with the seals (in violation of the Endangered Species Act). 

One woman was held underwater, and a few people were nipped by the monk seal, which was caught yet again, this time at La Pérouse Bay.  RM-34 then taken to the remote Johnston Atoll, a distance of about 800 miles (1,287 km).

In October of 2003, officials warned people not to feed a monk seal that had been begging for food in Kaua‘i’s Nāwiliwili Harbor.  The 600-pound (272-kg) adult male was nicknamed Lucky due to its prominent body scars from an unknown encounter that the seal managed to survive.  Scientists call the seal K07. 

After twin female monk seals were rescued by researchers in 2006, the Captive Care Project was begun.  In 2007, the monk seal twins (known as P022 and P026, their flipper tag numbers) and four other monk seals were released with satellite tracking devices attached so scientists and the public can follow the seals’ movements on a website (www.pifsc.noaa.gov/psd/captivecareproject.php), which was developed by National Oceanic and Atmospheric Administration (NOAA).

Protecting the Hawaiian Monk Seal

Always stay clear of monk seals you see on the beach, because disturbing them could alter their behavior and decrease their natural chances for survival.  Monk seals spend about one-third of their time resting on the beach. 

Sharks are natural predators of monk seals, and if monk seals are scared back into the water when they should be resting (e.g., after eating), then they may be more vulnerable to sharks. 

From 1987 to 1996, there were at least 173 documented cases of monk seals entangled in debris (e.g., fishing lines, nets, and ropes).  Anyone seeing an entangled or injured monk seal, or a monk seal being harassed by humans, should call the toll-free 24-hour National Oceanic and Atmospheric Administration hotline number: 888-256-9840.  The Marine Mammal Hotline is 888-256-9840.

[Photograph: Monk seal]