Latest News
For Teachers
For Keiki (Kids)
About the Area
Photo Images
Video Images
Maps and Satellite Images
More Info

You are here: /main/research expeditions/June-July 2006/ Day 17

Researching the Hawaiian Monk Seal on Kure

Patricia Greene, NOAA Teacher-at-Sea

A young monk seal pup recently weaned.  Photo: James Watt.

A young monk seal pup recently weaned. Photo: James Watt.

The majority of the Hawaiian monk seals are found in the Northwestern Hawaiian Islands from Nihoa Island to Kure Atoll with a small number on the main Hawaiian Islands. Traditionally Monk seals have been killed for food by early sailors. The species was declared depleted under the Marine Mammal Protection Act in 1976 following a 50% decline in beach counts. Monk seals were also classified as “endangered” under the Endangered Species act in 1976. Undersized female pups from the French Frigate Shoals were rehabilitated and released on Kure from the 1980’s until 1995 in an attempt to re-establish populations.

Approximately 90% of the monk seals remain at the island where they were born for life. During our recent visit to Green Island, I interviewed monk seal researchers Tracy Wurth and Antonette Gutierrez from the National Marine Fisheries Service. Tracy and Antonette have been in the field on Green Island since May 16, 2006 collecting data on the monk seal population.

Most pups are born between February and July with the peak in April and May. The newly born pup is totally black and weighs approximately 20 to 30 lbs. By the time they are weaned (30 to 40 days) they will increase their weight to over 100 lbs. Monk seals in the Northwestern Hawaiian Islands tend to wean their pups sooner at approximately 30 days, while seals on the Hawaiian Islands tend to nurse longer; as many as 60 days. Northwestern Hawaiian Island pups tend to be smaller in size as a result. Females give birth on beaches with shallow water to protect their pups from sharks. A female will not give birth until they reach five to ten years of age. By the time the researchers arrive on Green Island most female seals will have already pupped.

Tracy Wurth and Antonette Gutierrez from NOAA Fisheries conduct atoll counts to get a “snapshot” of the monk seal population at Kure Atoll.  Photo: Patricia Greene.

Tracy Wurth and Antonette Gutierrez from NOAA Fisheries conduct atoll counts to get a “snapshot” of the monk seal population at Kure Atoll. Photo: Patricia Greene.

Tracy and Antonette conduct seal patrols on Green Island on a daily basis. They walk the beach collecting information on each seal observed. Approximately every fourth day they conduct an atoll count, which is a standardized seal patrol that is time sensitive and basically captures a “snapshot” of the population at a given time. For their atoll counts the seal team start their survey on Green Island at 1:00 pm and when finished take their boat to Sand islet and conduct a survey there. Atoll counts take the researchers approximately three hours.

Field researchers from the National Marine Fisheries Service on all the Northwestern Hawaiian Islands keep careful track of each seal in the colony; identifying individuals with applied tags and bleach marks as well as natural markings or scars. Every seal is photographed by taking photos of all sides and flippers and are documented in a digital photo library. New pups are tagged as soon as they are weaned at 30 to 40 days. Plastic “temple” tags are applied to each rear flipper and injected with a micro-chip pit tag. Flipper tags are color specific to each island; Kure uses grey tags, while Pearl and Hermes uses light blue tags. The letter assigned will tell researchers what year the pup was born. One pup with a bleach mark “Z26” swam close enough to our boat for us to read his marks. Later the researchers knew exactly what seal we had seen and told us it was a “weaner;” a pup born is this year that had already weaned.

Monk seal biologist, Tracy Wurth, discusses the importance of seal scat with the educators.  Photo: Claire Johnson/NOAA.

Monk seal biologist, Tracy Wurth, discusses the importance of seal scat
with the educators. Photo: Claire Johnson/NOAA.

During the field season information is collected on injuries, wounds, illnesses, abnormalities, as well as deaths/disappearances, births, and any unusual events. If a dead seal is found a necropsy is performed and samples from organs and tissues are collected. Researchers also collect specimens of scat and spew (vomitus) in an effort to analyze the monk seal’s diet. Tissue plugs are taken from tagged pups for DNA analysis to determine maternity. Priorities for the Kure researchers include all of the above, while male aggression and shark predation mitigation is not a significant problem here at Kure Atoll. However, researchers are concerned about the future seal population due to low juvenile survival. As the current breeding females get older or die there will not be younger seals to take their place in the breeding population.

Researchers also collect marine debris such as nets on shore or in shallow water and move it to a secure location to be picked up at a later date by the National Marine Fisheries Coral Reef Ecosystem Division. The collection of marine debris is extremely important because monk seals can become entangled in the nets.

At Kure Atoll, the adult seal population in 2005 was 86 individuals with 23 pups born. The population at Kure has been slowly decreasing over the last several years. One major factor is the low juvenile survival rate due to lack of nutrients and resulting emaciation. However, this year their numbers show an increase in juvenile survival with a re-sight rate of over 60 percent. In the past the re-sight rate has been closer to only 30 percent.

While on Kure Atoll, the researchers enter their data in the field database system. When the researchers return from their assignment they will file their final report. This information will be summarized in published papers and used by various institutions such as the Hawaiian Monk Seal Recovery Team.

The future of the protected monk seal is unclear. Today, researchers estimate the total monk seal population in existence is approximately 1,300 to 1,600 seals. Researchers are concerned if the population continues to decline the total number could fall below 1,000 within the next five years. Scientists and researchers work together to find solutions to aid the recovery of the Hawaiian monk seal.

Talk About It!

Deep water foraging

Asked by Maggie from Dept. of Education on Nov 16, 2006.
Is deepwater foraging "new" in monk seals?

Answered by Frank Parrish, NOAA on Nov 16, 2006.
The capability for deep diving is not new, early dive recorders showed seal capable of making trips to the edge of the subphotic - so the question is are today's seals forced to dive deeper to find prey because of reduced oceanic productivity or competition with other predators. We don't have a good way to test this. Only recently have seals across the archipelago have been fitted with satellite tags and dive recorders to see where and what depths they visit. There is no similar data set from the past to compare with. If we had it and all the seals stayed shallow that would be really interesting. There are eels and slow moving fish in subphotic depths which as prey could offset the physiologic cost of diving to catch them.

Predator Abundance

Asked by Maggie on Nov 16, 2006.
Is predator abundance higher than in the past?

Answered by Frank Parrish, NOAA on Nov 16, 2006.
It is hard to know what the predator abundance and competition with monk seal was in the past. Its probably not an issue of more predators but instead more intense competition for less prey. Oceanic productivity in the region may have dropped in the recent decade. There are a number of physical and biological parameters that suggest this may have happened. If there is less prey for the predators to eat then there is more competition among the shark jacks and seals. Seals are good at flipping over rocks and digging out fish from the sand but being escorted by school of hungry predators has got to make things harder - particularly if you are a small seal. Diving deep might be a strategy to avoid it

Seals and deep diving

Asked by Maggie on Nov 16, 2006.
Can deep diving harm pregnant female seals?

Answered by Frank Parrish, NOAA on Nov 16, 2006.
Intuitively, it seems like evolutionary biology would take care of this but if you were able to convincingly show that seals were forced to dive deeper to find food or avoid predators then it would be reasonable area of study. However, we haven't instrumented pregnant females for obvious reasons.


Facing off with a beautiful threadfin butterflyfish.  Photo: Paulo Maurin

The abundance of fish in a healthy coral reef ecosystem are part of what makes the Northwestern Hawaiian Islands so special. Photo: James Watt

Members of the NOAA Maritime Heritage Program will be surveying some of the world's most beautiful and untouched submerged cultural resources during this expedition. Photo: Robert Schwemmer/NOAA

A Laysan Albatross fledgling practices how to take flight.  Photo: Claire Johnson/NOAA

Teacher Dena Deck gets familiar with the species found in the Hawaiian Archipelago.  Photo: Hans Van Tilburg/NOAA

A Laysan Albatross fledgling practices how to take flight.  Photo: Claire Johnson/NOAA

Chief Scientist Dr. John Rooney points out the tracks that have been mapped around Kure Atoll.

A “sunbow,” a rainbow without the rain, was the show of the night.  Note the large arc of light around the sun.

Home | News | About | Expeditions | Photos | Video | Maps
Discussions | Partners | Teachers | Keiki | More Info | Search
Contact Us | Privacy Policy
This site is hosted by the
Laboratory for Interactive Learning Technologies
at the University of Hawai`i