Hawaiian Monk Seal Conservation Efforts

There is no question that human disturbances impact Hawaiian Monk Seals and their habitats. Some effects are obvious, such as when seals get tangled in fishing gear and other debris left behind by humans. But other effects of human disturbances are more difficult to measure. For example, human activity near the beaches that seals use for pupping will cause mother seals to avoid these favored spots and instead choose locations that are less safe for themselves and their pups. This choice results in a decline in pup survival rates, which in turn results in fewer adult seals giving birth generations later.

The survival rate of the pups varies dramatically from island to island and from year to year. In the 1980s, the first-year survival rate was 80 to 90 percent, but in recent years, this rate has dropped to as low as 30 percent on some islands, such as on French Frigate Shoals. The low survival rate is especially significant given that female monk seals do not bear young until they are 6 or 7 years old, have only one pup per year, and may not pup every year. At French Frigate Shoals, young monk seals are being picked off by Galapagos sharks that have been observed attacking nursing pups in as little as 2 inches of water, claiming up to 35 percent of pups born at the shoals.

Biologists are now trying to improve the survival odds of pups with two new strategies – relocation and deworming. Six weaned seals were taken from French Frigate Shoals in August and released at Nihoa Island, where sharks are not as much of a threat. And as part of a trial deworming program, several juvenile seals at Laysan Island were given the first of several doses of medication to eliminate parasites to boost their health. Because research shows that many juveniles die from emaciation, scientists believe that climate changes may have reduced the monk seal food supply at some islands. A reduced food supply means increased competition, and juveniles often do not have the skills to compete.

While other species of seals swim hundreds of miles to feed or mate, Hawaiian Monk Seals do not leave their island chain home. Because the islands are so isolated, there is no buffer. There is no place for animals to go when conditions change, such as when the food supply decreases or the number of predators increases. With new technology, including ‘critter cams’, scientists can now observe their underwater behavior. Recently, researchers have been able to witness young monk seals competing for food with other species. Their health reflects the health of the entire marine environment in which they live. Therefore, our concern needs to center on the health of the complete habitat, not just the creatures themselves.