The Hawaiian monk seal is the most Hawaiian of Hawaii’s marine animals. They are seldom seen around the inhabited Hawaiian Islands, but are found in the northwest part of the archipelago from Nihoa to Kure islands. Maybe they are shy of people because they have been hunted so much. They are so named because they are solitary animals, similar to monks. They also have very little fur on the top of their head and the skin folds around the neck resemble a monk’s cowl collar.
There are three species of monk seals. The Caribbean monk has been extinct since 1952, the Mediterranean monk is endangered with fewer than 500 animals remaining. The outlook is dim for them as the countries surrounding their habitat have political priorities over saving the seals. The Hawaiian monk has been endangered since 1976 with a total population of only 1200 animals.
The monk seals have remained in tropical and temperate waters while relatives have moved to colder polar climates. Tropical habitats have fewer resources and fewer haul-out areas. Such areas also are favored human habitats and often humans rearrange the monk habitats.
It was explained, “The objective of this research is to monitor the population including the age, sex, and numbers of seals and identify the beaches used to determine if there is a seasonal pattern. Data will also show the composition of the population, reproductive and survival rates, and movement to other atolls. It will also identify birth sites and nursery beaches as well as the diet, by analyzing collected scats. Documentation of scars, injuries, entanglements, and other threats will be made. Potential entangling debris will be collected and disposed of and any seal found entangled will be freed. And finally we’ll determine how disturbances, including aircraft traffic, affect the seals.”
The Hawaiian monk seal history is rather a sad one. As human activity increased many seals were clubbed to death for meat, oil, and skins. With the disturbance of hauling-out areas mothers and babies were forced out to sea where sharks further reduced the population. Others drowned accidentally when entangled in lost fishing nets that drift from the North Pacific.
Seals feed on eels, small reef fish, octopus, and lobster. They have been known to dive 500 feet and remain under water for as long as 20 minutes when feeding. They can eat as much as 10% of their body weight each day providing a thick layer of blubber as an energy reserve. Although the monks live in warm waters their blubber layer is equal to that of seals in colder climates. Their life span may reach 30 years. Generally seals remain close to the island of their birth. Adult females often have a pup each year. Monk seals are normally polygamous. In some areas this has become a problem when males out-number females. Aggressive courtship, known as mobbing, has resulted in injury and even death of some females and juveniles. In recent years wildlife managers have identified the aggressive males and moved them to other islands.
A newborn pup weighs 35-40 pounds and will quadruple his weight during the 40 day nursing period. A pregnant 7-foot female can weigh 600 pounds and will lose half of that during the nursing period as she does not leave her pup during that time, even to feed. The weaned pup will slowly lose weight as he learns to feed by trial and error on his own. He will feed around his birthplace.
A weaned pup has been described as looking like a silver football with big black eyes and whiskers at one end and floppy flippers at the other end. At one year the pup is generally 4 ½ feet long and weighs about 100 pounds.
Breeding season is generally spring and summer. Gestation is about 10 ½ months with most births occurring in March to May, although births have been recorded in every month. New born pups have black fuzzy short hair which falls out during nursing and is replaced with silver-gray fur on the back and creamy white fur on the underside. Subsequent molts occur annually. Only elephant and monk seals molt each year. Each animal has his own molting schedule, they do not all molt at the same time of year. The fur is attached to the epidermis and comes off in strips. The process takes about two weeks. The seal remains on the beach during molting and does not feed during that period. The new fur comes in on the dermis layer.
The monk seal bone structure is quite different from that of other seal species. Its limbs and flippers are very short. On land they are very awkward, unable to haul out on rocks like other species. They kind of wiggle and inch their way along. But in the water they are sleek and graceful.
The Midway seal population is the most depleted population in the northwest Hawaiian Islands. The high Midway human population, without a doubt, was a big contributing factor as the residents made ample use of the beaches.
During this ten day research project we spent some time washing and examining seal scat the biologist had collected. It was amazing the things we found. It was a fascinating activity.
There were times when I was pretty bored on this project, but it certainly was interesting and educational!
