Hawaiian monk seal

Photograph by Joel Sartore, National Geographic Photo Ark
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The endangered Hawaiian monk seal lives in the remote Northwestern Hawaiian Islands. Sea level rise brought on by climate change is putting its habitat and food supply in jeopardy.

Photograph by Joel Sartore, National Geographic Photo Ark

What is the Hawaiian monk seal?

The Hawaiian monk seal is named for its folds of skin that somewhat resemble a monk's cowl, and because it’s usually seen alone or in small groups. Pups are born black, but as they age they morph into shades of gray and brown. Hawaiian monk seals molt once a year, shedding the top layer of their skin and fur.

Hawaiians call the seal `Ilio holo I ka uaua, which means, “dog that runs in rough water.” This species is one of the most endangered marine mammals in the world.

Habitat and diet

Most seals are at home in frigid waters, but the Hawaiian monk seal is a rare tropical exception. Hawaiian monk seals live in the remote Northwestern Hawaiian Islands. These small islands and atolls are either uninhabited or little-used by humans. They are also surrounded with teeming coral reefs, which serve as great foraging grounds for skilled seals to swim and dive for fish, spiny lobsters, octopuses, and eels.

Monk seals spend most of their time at sea, but they come ashore to rest on beaches and use fringe vegetation as shelter from storms.

Parenting

Mother monk seals are dedicated and remain with their pups constantly for the first five or six weeks of their lives. They don't eat during this time and may lose hundreds of pounds. After they’re finished nursing, females leave behind their pups and return to their solitary lifestyle.

Threats to survival

Like the two other species of warm-water monk seals, the Mediterranean and Caribbean monk seals, the Hawaiian monk seals’ survival is tenuous. The Marine Mammal Center, a conservation nonprofit that runs a Hawaiian monk seal hospital, says this species was hunted to the brink of extinction in the late 19th century. Then from 1983 to 2011, the population declined about 20 percent.

The low-lying islands where they live are losing shoreline to sea level rise and erosion from storms, putting the beaches where they have their pups at risk—one has already disappeared. Furthermore, juvenile monk seals already struggle to compete with apex predators like sharks for food, and researchers worry that climate change-induced disruptions to the ecosystem will only make it harder on the pups.

Humans are also a threat. Monk seals have also been victims of fishing gear, getting accidentally hooked or tangled in nets. Deliberate killing of monk seals has also been a problem.

Sharks are natural predators of Hawaiian monk seals, but during one unusual period, shark attacks at the French Frigate Shoals shot up, killing nearly a quarter of all pups born between 1997 and 2010. This kind of predation continues to be a concern.

Male monk seals sometimes kill pups or females of their own species in group attacks called "mobbing," which happen during attempts at mating.

Conservation

Today, many protection efforts are in place to save the Hawaiian monk seal, which has been listed as endangered under the U.S. Endangered Species Act since 1976. The International Union for Conservation of Nature reports that “virtual all of the land and waters” in the Northwestern Hawaiian Islands are protected and that this species is the focus of one of the most proactive marine mammal recovery programs in the world.

Juvenile and adult female seals historically have been the focus of recovery programs, which have relocated pups away from shark hunting grounds and also relocated adult males to prevent them from attacking females and pups. Other recovery efforts have included more tightly regulating local fisheries, educating the public to promote the peaceful coexistence of humans and seals, and vaccinating seals against diseases.

Though the Hawaiian monk seal population continues to decline, research has proven that 30 percent of the species’ population is alive today thanks to these interventions.

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