Return Voyage of NOAA Research Vessel Focuses on Better Understanding of Whales and Dolphins in the Western Pacific

April 19, 2010

As part of an expanding program to better understand populations of whales and dolphins in the western Pacific Ocean, NOAA scientists from the Pacific Islands Fisheries Science Center are conducting a survey of these cetaceans in waters between the Mariana Archipelago and Hawaii. The survey is the primary objective of the final phase of a 3.5-month long research cruise by the NOAA Ship Oscar Elton Sette in support of NOAA's broad mission, which includes the conservation and management of marine ecosystems. The multi-purpose expedition began with a cetacean survey during the ship's transit from Honolulu to Guam and included extensive studies of fishery resources and oceanography in waters of the Marianas in cooperation with many partners including academia and government agencies of Guam and the Commonwealth of the Northern Mariana Islands.

Cetaceans will be surveyed along this oceanic trackline 
        while the NOAA Ship <em>Oscar Elton Sette</em> is on its return transit from Guam to Hawaii. An underwater 
        acoustic recorder will be retrieved at Wake Island and replaced by another one to monitor cetaceans in local 
        waters. Colored lines are boundaries of the 200-mile Exclusive Economic Zones (EEZ).
Cetaceans will be surveyed along this oceanic trackline while the NOAA Ship Oscar Elton Sette is on its return transit from Guam to Hawaii. An underwater acoustic recorder will be retrieved at Wake Island and replaced by another one to monitor cetaceans in local waters. Colored lines are boundaries of the 200-mile Exclusive Economic Zones (EEZ).

During its 3315 nautical mile return voyage to its home port at Ford Island, in Pearl Harbor, the research vessel will retrace the cruise track followed during the opening segment of the cruise. While the ship is underway, members of Sette's scientific crew stationed on the flying bridge will scan the sea surface looking for cetaceans using 25x150 "big-eye" binoculars. When they sight a pod (group) of cetaceans, they will identify the species involved and collect data on the size of the pod and its behavior. In addition, they will take photographs of the animals to aid in their identification and collect biopsy samples of skin tissue for later genetic analysis. The various kinds of data collected will be used for studies on cetacean population structure and abundance.

During the cetacean surveys, a 4-element hydrophone array will be towed behind the ship to record sounds of vocalizing cetaceans and their location along the cruise track. The acoustics data will be used in conjunction with the observers' sighting data to identify the species of cetaceans encountered. Sonobuoys may be deployed to collect additional low frequency acoustic data from large baleen whales.

When the ship reaches Wake Island, it will recover a High-frequency Acoustic Recording Package (HARP) that was placed on the seafloor during the earlier transit to Guam. Another HARP will be deployed to continue the long-term monitoring of cetacean presence at the site.

In addition to surveying cetaceans, during the ocean crossing the scientific crew will routinely collect data on the vertical distribution of ocean conductivity and temperature by deploying a CTD instrument and measure the density of potential cetacean prey (small fish and other marine organisms) in the water column using the ship's EK-60 sonar.

The expedition is under the scientific leadership of Marie Hill, a PIFSC marine mammal specialist employed by the University of Hawaii Joint Institute for Marine and Atmospheric Research. She will lead a team of researchers from PIFSC, JIMAR, the NOAA Southwest Fisheries Science Center, NOAA Alaska Fisheries Science Center, Scripps Institution of Oceanography (University of California San Diego), and NOAA contractors. In addition, a participant in NOAA's Teachers At Sea program will be a member of the cruise scientific party She will join in all aspects of the research under the guidance of NOAA scientists and report her experiences along the way in a Teacher at Sea blog.

After scientists carefully prepare a High-Frequency 
        Acoustic Recording Package (HARP) in the shipboard laboratory, they deploy it over the side of the ship. The 
        instrument passively senses sounds produced by marine animals, including vocalizations of whales and dolphins, 
        and records them for later analysis.  The HARPS are useful tools for long-term monitoring of cetacean presence 
        and activity, particularly at remote sites like Wake Island.
After scientists carefully prepare a High-Frequency Acoustic Recording Package (HARP) in the shipboard laboratory, they deploy it over the side of the ship. The instrument passively senses sounds produced by marine animals, including vocalizations of whales and dolphins, and records them for later analysis. The HARPS are useful tools for long-term monitoring of cetacean presence and activity, particularly at remote sites like Wake Island.