Among the last of their kind, the Hawaiian monk seal (Monachus schauinslandi) is one of the rarest marine mammals in the world. Large and possessing canine-like features, the Hawaiians call the seal the “llio holo I ka uaua” which means “dog that runs in rough water.” The common name comes from the folds of skin around the seal’s neck that resembles the hood of a monk, and their preference to live solitarily or in small groups. Their life span is between 25 and 30 years. Born completely black, the pup sheds its fur after a month and grows the soft gray back and tan underbelly of an adult. Patches of red or green have been commonly seen on the fur of monk seals due to attached algae. The average adult weighs 375-500 pounds and measures 7-7.5 feet in length, with females being larger than the males. Pups weigh only 25-30 pounds at birth and gain four times their body weight during their first six weeks. Hawaiian monk seals are one of two remaining monk seal species; the Mediterranean monk seal is also endangered and the Caribbean monk seal has been extinct since the 1970s.
Behavior and Breeding
Monk seals are typically solitary animals that spend two-thirds of their life in the tropical Pacific waters. They mate in the water but give birth on the shore, and haul-out on sands, rocks, and even coral. Expert divers, they typically dive to depths of over 40 feet at least 35 times a day. They can dive up to 500 feet using a technique that slows their heartrates to eight times less than normal, reducing the need for oxygen. Adults are nocturnal hunters. Most populations of Hawaiian monk seals have more males than females, making competition for a mate fierce. So fierce, in fact, that males sometimes swarm a female and can injury or even kill her in the process. Once a female is pregnant, the gestation period lasts 10-11 months, after which she gives birth to a single pup on shore. She then nurses the pup and stays as protection and the sole food source for five weeks before returning to the ocean, leaving the youngster to fend for itself. While the pup gains over 75 pounds (sometimes as much as 300 pounds) the mother loses up to two-thirds of her own body weight. Some female monk seals have been documented fostering and nursing pups whose mothers either die or abandon their pup too early.
Habitat and Diet
Most of the population of Hawaiian monk seals can be found in the Northern Hawaiian Islands, but have become more frequently noted on the main Hawaiian Islands. Monk seals can be seen resting on sandy beaches, away from human activity, on sunny days between hunts for food. The carnivorous seals prey primarily on octopi, fish, crabs, spiny lobsters, and eels. The coral reefs surrounding the islands house the food monk seals are particularly fond of, but also the predators that enjoy a taste of seal. The only known natural predators of the Hawaiian monk seals are the tiger and Galapagos sharks.
Endangered according to the U.S. Endangered Species List, the State of Hawaii’s Endangered Species list, and IUCN Red List of Threaten Species, the Hawaiian monk seals were on the edge of extinction at the end of the 19th century. Today, they have declined on average more than 5% annually since 1989 and only 1,300 are documented to exist in the wild. Monk seals face many threats, both natural and human that have led to their dwindling numbers. Changes to sea level and temperature, diseases, predators, and extreme competition when mating have killed off a fair amount of seals. Low genetic diversity also plays a role with the changes to the ocean and diseases they are exposed to. However, the main threat to the Hawaiian monk seal is us. Human activity around seal beaches, especially nursing mothers, and inhabiting areas that were once prime spots for the seals to give birth and relax have driven away many of the creatures. Fisheries have accidentally caught monk seals in their nets and ocean pollution causes illness and death. Specialists believe that, based on the statistical drop in numbers, there will be less than 1,000 Hawaiian monk seals by 2020.
Many organizations have devoted time and money to raising the population rates. Habitats have been protected legally and humans have been educated more thoroughly on keeping a safe distance and respecting the monk seal’s habitat. National Marine Fisheries Service oversees the protection efforts, aided by government and nonprofit organizations to hopefully replenish the species. Several remote islands are protected by the U.S. Fish and Wildlife Services as safe havens. Critical habitat was declared in 1988 encompassing beaches and ocean in the northern region of the Hawaiian Islands. Conservation efforts have removed plastic debris from the waters and shorelines and rehabilitated injured seals back to health. Volunteers are always needed to help with legislation forming and ocean clean-up. With an extreme amount of effort and dedication, the decline can end and the Hawaiian monk seal may be able to flourish in the future.