Hawaiian Monk Seal and Threats
Hawaiian Monk Seals face a new threat from a pathogen in cat feces that is carried to the ocean in polluted runoff and sewage. Experts worry that the disease, toxoplasmosis, will derail efforts to restore this endangered species. Over the past ten years, the cat parasite has killed at least four monk seals in the main Hawaiian islands – two from Kauai, one from Oahu, one from Molokai, and perhaps more. In the past decade, toxoplasmosis has been regularly found in a wide range of marine mammals, including whales, dolphins, as well as seabirds, and the endangered Hawaiian crow.
No studies have been done in Hawaii, but in California, researchers have found that it infects sea otters mainly though runoff from urban areas. Flushing cat litter down the toilet is one pathway, since sewage treatment does not always kill the parasite’s hardy eggs, called oocysts. Studies have found that oocysts can live for at least two years in sea water.
Although domestic cats are considered the main source, feral cats in remote areas also transmit the disease. Nearly 40 percent of cats captured from the slopes of Mauna Kea, on the island of Hawaii, tested positive for toxoplasmosis. The state Division of Forestry and Wildlife estimates that 300,000 to 400,000 free-ranging cats live on Maui alone.
The Hawaiian Monk Seal (Monachus schauinslandi) is considered the most endangered pinniped in the United States. Their overall population is declining at a rate of about 4.5 percent a year. The good news is that in recent years, their numbers have been growing in the main Hawaiian islands. With only about 1,100 monk seals left in the wild, each death is very concerning, and now toxoplasmosis is one of the primary concerns. To raise public awareness about toxoplasmosis and cat feces, NOAA has begun talking with the Hawaii Humane Society, various interest groups, and the health department.
Hawaiian Monk Seal
The Hawaiian Monk Seal is an endangered seal that is endemic to the waters around the Hawaiian Islands. Known to the native Hawaiians as ʻIlio holo i ka uaua (dog that runs in rough waters), they get their common name from their bald appearance, solitary habits, and folds of skin around their heads which resembles a monk’s hood. Newborn pups are black and woolly with fuzzy short hair. Young seals are silver with creamy white stomachs, chests, and throats. Mature seals feature a gray pelage, which turns brown with weathering. Adult males average 300 to 400 pounds and 7 feet in length, while adult females tend to be 400 to 500 pounds and at 8 feet in length. Pups average 30 to 40 pounds at birth and 40 inches in length. Life expectancies are from 25 to 30 years, but although many protection efforts are in place, their numbers have fallen more than ten percent per year since 1989.
Nearly 90% of Hawaiian Monk Seals live around the tiny, uninhabited islands and atolls in the upper reaches of the Hawaiian archipelago. But, for approximately 25 seals, the waters and beaches of Kauai are home. These islands 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 that they usually catch at night. In the daylight hours, the seals come ashore to rest on beaches. When on land, they may look lethargic, sick, or even dead, but they should not be disturbed or approached.
Hawaiian Monk Seals molt annually. During a two-week span, the seal loses its entire layer of skin and overlying fur. The old skin and brown mottled fur strips away, leaving a sleek, dark grey coat underneath. Molting seals often seem distressed, and may have mucous around the nose and runny eyes. They remain on the beach for longer periods than usual and often appear uncomfortable, writhing in the sand to help remove skin. Also, the stench from the molting skin can be quite unpleasant when one is in close proximity to the animal. While these conditions might lead someone to assume they are sick or injured, it is part of a normal annual cycle.
