Outrigger - Print

Spotlight: Hawaiian Monk Seal

Thursday, October 07, 2010

At the Waikiki Aquarium*

This rare seal is endemic to the Hawaiian Islands and is found no where else in the world. Its primary natural habitat lies in the Northwestern Hawaiian Islands, the most remote part of the Hawaiian chain. These mostly uninhabited islands and atolls to the northwest of Kauai comprise a National Wildlife Refuge. Occasionally, monk seals are sighted around the major high islands of the Hawaiian chain. Recently, some females have even come ashore to give birth and nurse their pups; these individuals are considered to be “stragglers” from the main population to the northwest.

Common name: Hawaiian monk seal
Hawaiian name: ilio-holo-i-kauaua
Scientific name: Monachus Schauinslandi
Distribution: Hawaiian Islands
Size: 400-600 pounds (180-270 kg), 7 – 8 feet (2.1-2.4m) long
Diet: Reef fishes and invertebrates
Hawaiian monk seals are both endemic and endangered

The Hawaiian monk seal is an endangered species, with a population estimated at about 1,300. It is protected by both Federal and State laws.

Hawaiian monk seals naturally spend about a third of their time resting and sleeping on shore. They are not “lazy,” but conserve energy between their hunting and foraging trips. They are known to feed on reef fish, octopus, and lobster, as well as other types of prey. When they are hunting on the reef, they may stay under water for more than 15 to 20 minutes, depending on how deep they dive and how active they are under water. Monk seals have been known to dive to about 1,650 feet (500m), but most of their diving is probably much shallower. Large tiger and Galapagos sharks are their main natural predators, and the presence of sharks may be another possible reason for the seals to minimize their time in the water (and maximize their time on the beach). Monk seals are not social seals and do not form harems or other large groups seen in some seal and sea lion species. The name monk seal may come from their solitary nature.

Females give birth for the first time at five to nine years of age. Seal pups are usually born in the spring. They nurse for 5 to 6 weeks and can quadruple their birth weight of 35 pounds (16kg). After weaning, pups live off their fat while they learn to forage for themselves. Some research and recovery projects aim to assure pup and juvenile survival in the wild.

You can help, too

1. Report monk seal sightings but don’t approach or disturb them;

2. Learn about monk seals and their need for protected habitat;

3. Help control marine debris; dispose of rubbish carefully; reduce, reuse, recycle;

Telling seals from sea lions

The Hawaiian monk seal is a pinniped, a member of the group of marine mammals that includes the seals, sea lions, fur seals, and walruses. The monk seal is a “true seal” and differs from seal lions (eared seals) in several significant ways:

1. True seals lack the external ear flaps seen in the sea lions. The monk seal’s ears are visible as small holes on the sides of their head; a narrow canal leads to the middle ear.

2. True seals do not “walk” on land because they cannot support their weight on the front flippers and cannot rotate their hind flippers forward. When true seals move on land, they undulate their bodies instead of walking. In contrast, sea lions can walk on land because they are able to rotate their flippers forward to support the hind part of the body in a walking motion.

3. Seals and sea lions also differ in the way they swim through the water. True seals use their hind flippers, held together vertically (almost like a fish’s tail) and moved in a side-to-side motion that pushes them through the water; their small front flippers are used for steering and maneuvering. Sea lions, on the other hand, use their large front flippers for power, pulling themselves through the water, and the rear flippers act as rudders for steering.

4. Monk seals don’t “bark” like sea lions. Instead, Hawaiian monk seals have a number of different sounds, or vocalizations, that they produce including a deep guttural call that almost sounds like a belch.

5. Biologists debate whether or not true seals evolved from the same ancestral stock as sea lions and fur seals.

Monk seals resident at the Waikiki Aquarium

The two Hawaiian monk seals at the Waikiki Aquarium are here under special permit from the National Marine Fisheries Service. While resident at the Aquarium, the monk seals are part of a behavioral research program. The research is not intrusive or harmful to the seals, but allows us to make observations and learn more about their biology and behavior so that we can work to increase their numbers in the wild.

Both male animals are sexually mature adults, but may continue to put on a little more length and weight. Their diet here at the Aquarium consists mainly of herring, smelt and squid supplemented with vitamins.

Our resident seals are probably not “lonely,” but would spend much of their time alone or away from other monk seals. Males may actually be very aggressive towards one another and towards females and pups, so even in their natural habitat, monk seals tend to spread out on available beaches.

Monk seal profiles:

Nukaau (meaning “sleak swimmer”)
Called Nuka for short, this seal was born on Laysan Island in 1981 and was brought to the Aquarium as a juvenile in 1983. Nuka arrived with a large scar on his abdomen possibly caused by an encounter with a shark or entanglement in marine debris. He measures almost 8 feet (2.4m) in length and weights between 380-420 pounds (172-190kg).

Makaonona (“soft or gentle eyes”)
Called Maka for short, he was brought from French Frigate Shoals in the summer of 1984. He was only 3 years old and weighed only 60 pounds. He had been weaned early, abandoned or orphaned, and probably would not have survived if he had not been brought to the Aquarium and given special care. Now an adult, he is about 7 feet (2.2m) long and weights between 370 and 390 pounds (168-177kg).

Monk Seal Research

Cooperative research programs, under our research permit, seek to aid the recovery of the species. The Waikiki Aquarium is proud to be part of this effort. While resident at the Aquarium, the monk seals are part of a research program that studies their behavior and physiology. The research is not intrusive or harmful to the seals, but allows us to make observations and learn more about their biology and behavior so that we can work to increase their numbers in the wild.

Classification:
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Pinnipedia
Family: Phocidae
Genus: Monachus
Species: schaunislandi

Waikiki Aquarium was created in 1904 and is the third-oldest public aquarium in the United States. In 1912, a private contribution established a marine biology laboratory at the Aquarium. In 1919, the Aquarium became part of the University of Hawaii.

Exhibits, programs, and research focus on the aquatic life of Hawaii and the tropical Pacific. Over 3,300 organisms in the Aquarium’s exhibits represent more than 420 species of aquatic animals. Every year, roughly 350,000 people visit the Waikiki Aquarium.

2777 Kalakaua Avenue
Honolulu, HI 96815-4027
Hours: Daily 9 to 5
www.waquarium.org