Cetacean Surveys Continue in Waters of the Mariana Islands

In April, the PIFSC's Cetacean Research Program conducted surveys for cetaceans in the waters surrounding Guam and the Commonwealth of the Northern Mariana Islands (CNMI) in an effort to further develop a record of cetacean occurrence in the region and to gather photos and biopsy samples for population studies. PIFSC has been conducting similar surveys in the region since 2010, but this was the first springtime expedition. The project was carried out in partnership with the U.S. Navy. Over 15 days of survey effort, 15 groups of cetaceans of various species were sighted, including spinner dolphins, spotted dolphins, bottlenose dolphins, rough-toothed dolphins, melon-headed whales and pygmy killer whales. Thousands of photographs of the mammals were taken and will be used to assess their movements, abundance and population connectivity. Biopsy samples from melon-headed whales and bottlenose dolphins will contribute toward ongoing studies of genetic population structure in the Marianas region as well as a Pacific-wide evaluation of population connectivity for these species. Two satellite tags were deployed on melon-headed whales off Tinian, providing five and 17 days of movement data. Tag tracks suggested broad movement south to Rota, offshore to reefs west of Saipan and north to nearly Farallon de Medinilla. The research team returned to the Marianas in May, conducting additional small boat-based surveys in Guam, Rota, and Saipan. A survey of cetaceans in waters of the CNMI, including the Islands Unit of the Marianas Trench Marine National Monument, from the NOAA Ship Oscar Elton Sette has been delayed due to maintenance issues with the ship.

Rough-toothed (front) and bottlenose dolphin off Aguijan in the Northern Mariana Islands (NOAA photo by Daniel Webster).
Rough-toothed (front) and bottlenose dolphin off Aguijan in the Northern Mariana Islands (NOAA photo by Daniel Webster).
Satellite-determined tracks of 2 melon-headed whales tagged near Tinian and monitored from April 18 to May 4 2014 during PIFSC 
        cetacean surveys in the Northern Mariana Islands.
Satellite-determined tracks of 2 melon-headed whales tagged near Tinian and monitored from April 18 to May 4 2014 during PIFSC cetacean surveys in the Northern Mariana Islands.