NOAA Ship Oscar Elton Sette Supports Monk Seal Research and Cetacean Surveys in the Northwestern Hawaiian Islands

August 13, 2008
Hawaiian monk seal
Hawaiian monk seal

The NOAA Ship Oscar Elton Sette is at sea for 22 days on a scientific expedition to support Pacific Islands Fisheries Science Center (PIFSC) staff studying monk seals and cetaceans in the remote Northwestern Hawaiian Islands (NWHI).

Work on the highly endangered Hawaiian monk seal is being carried out by the Monk Seal Research Program, the PIFSC group responsible for monitoring the status of the seal population, conducting research to better understand factors affecting abundance of the seals, and finding ways to enhance the population's recovery. To this end, the program operates seasonal field camps at the six major monk seal breeding locations in the NWHI. During its current expedition, the Sette will pick up scientists and their equipment from field camps at French Frigate Shoals, Laysan Island, and Kure Atoll, where seasonal studies have been completed. The vessel's crew will also establish camps at Pearl and Hermes Atoll and Lisianski Island and conduct a census of seals at Nihoa Island and Necker Island.

Under the direction of Chief Scientist Chad Yoshinaga, field staff and Sette personnel will load all equipment and supplies from the dismantled island camps onto the ship, materials which have supported teams of 3-4 scientists for 4 months of arduous field work. Included are tents, stoves, solar power arrays, computers, leftover food, small boats, and more. Everything brought ashore is removed and must be transported by hand and shuttled via small boats from the islands to the ship anchored offshore.

At Necker and Nihoa Islands, scientists will spend a day at each place to count seals, document tagged seals, and apply identification tags to weaned seal pups. Identifying seals with tags at these two NWHI locations is important, as these islands are close to the Main Hawaiian Islands (MHI). Subsequent sightings of the tagged seals will reveal the extent of seal movements between the NWHI and the MHI, something currently unknown. Researchers are also conducting a pilot study to try to increase juvenile seal survival. They will transport 6 weaned seals from French Frigate Shoals, an area of low survival, to Nihoa Island, where survival is expected to be higher. The experiment will help determine the feasibility of using such relocations to increase juvenile female survival in the future.

Spinner dolphin
Spinner dolphin

In addition to the population assessment research at Nihoa Island, field staff will conduct a monk seal foraging ecology study there. Scientists will set up a short-term camp on the island and deploy satellite tags on seals. These tags will record data on the movement and dive patterns of the seals and later transmit the data via satellite to PIFSC computers. The data will provide scientists with key information on the seals' foraging behavior. During this study, scientists will describe the health and disease status of the Nihoa Island seal population for the first time. The work is being done in collaboration with researchers at two California institutions, the Moss Landing Marine Laboratory and The Marine Mammal Center.

While the Sette is en route between islands, staff of the PIFSC Cetacean Program will conduct sighting surveys of spinner dolphins and other cetaceans at the sea surface. The sightings will improve understanding of the occurrence, distribution and habitat of cetaceans in the region.

Besides the biological research on monk seals and cetaceans, shipboard personnel will collect oceanographic data on subsurface ocean temperature and conductivity periodically during the cruise by taking 'CTD' measurements. At selected stations, the CTD instrument will be launched from the ship. Trailing a thin copper wire connected to computers on the ship, the instrument will measure water Conductivity, Temperature, and Depth (hence the name 'CTD') as it sinks and transmit the data over the wire back to the ship. The data will be added to a comprehensive NOAA oceanographic database and used to better understand large-scale phenomena like climate change and the dynamics of local features like oceanic fronts.

The cruise will also provide support for several partner agencies working in the NWHI. Supplies and equipment will be transported for the U.S. Fish and Wildlife Service, which maintains stations at French Frigate Shoals and Midway Island and a permanent field camp at Laysan Island. The cruise will transport personnel and supplies to a field camp operated by the State of Hawaii Division of Forestry and Wildlife at Kure Atoll.