Mariana Archipelago Cetacean Survey (MACS) Underway

May 8, 2015
Melon-headed whales. NOAA photo by Andrea Bendin.
Melon-headed whales. NOAA photo by Andrea Bendin.
Visual observers utilize hand held binoculars and pedestal mounted "big-eyes" to search for cetaceans. NOAA photo by 
        Andrea Bendin.
Visual observers utilize hand held binoculars and pedestal mounted "big-eyes" to search for cetaceans. NOAA photo by Andrea Bendin.
Deploying  a High-frequency Acoustic Recording Package (HARP) which includes flotation, hydrophone, data-logging, and
        other components.
Deploying a High-frequency Acoustic Recording Package (HARP) which includes flotation, hydrophone, data-logging, and other components to monitor cetacean vocalizations.

On May 8 a team of cetacean observers, acousticians, and oceanographers will depart Guam to start the Mariana Archipelago Cetacean Survey (MACS). The team is led by Dr. Erin Oleson, the Leader of the PIFSC Cetacean Research Program (CRP), and most of the CRP staff, researchers from the University of Hawaii and Southeast Fisheries Science Center, as well as an undergraduate student in Natural Resource Management from Northern Mariana College. The team will survey for cetaceans throughout the archipelago over 30 days, conducting systematic surveys within 50 nmi of the archipelago, as well as focused near-island work at each of the islands north of Saipan. The survey team searches for cetaceans using 25x mounted binoculars called "big-eyes" as well as with a towed hydrophone array to listen for vocalizing animals that may be submerged or otherwise be hard to see.

CRP has been conducting near-shore small-vessel based survey for cetaceans near the southern islands of the archipelago (Guam Rota, Tinian, and Saipan) since 2010. As part of that work they have encountered several tropical and sub-tropical species and have built photo-identification catalogs of spinner, bottlenose, and rough-toothed dolphins, and short-finned pilot, false killer, and pygmy killer whales. They have also collected several hundred biopsy samples from these species and others, including sperm whales and humpback whales, and deployed several dozen satellite tags on short-finned pilot and false killer whales to examine animal movements. Each year the team re-sights some of the same individual dolphins and whales resulting in a preliminary assessment of animal movements and population structure within the southern portion of the archipelago. Genetic analysis of the tissue samples also suggest finer-scale population structure. The primary goal of the MACS cruise will be to extend this work to the northern islands to understand how animals there may fit into the structure we are starting to piece together in the southern islands. The team is prepared to collect genetic samples, deploy satellite telemetry tags, and collect photographic, acoustic, and behavioral information during the survey. Understanding the structure of populations is the first step toward assessment of cetacean population health in the region, one of the Center's mandates under the Marine Mammal Protection Act.

In addition to surveys, CRP has maintained two long-term acoustic recorders near Saipan and Tinian since 2010. These recorders provide information on species occurrence and behavior throughout the year, and allow for examination of seasonal presence and relative abundance of a variety of vocal cetacean species. The recordings have proven particularly enlightening for species that the visual survey team rarely encounters, such as beaked whales and baleen whales. As part of the MACS cruise both of the existing instruments will be recovered and redeployed with new batteries and hard drives, enabling another year of monitoring. In addition, the team will deploy a new recorder near Pagan to listen for migratory baleen whales further north in the archipelago. That recorder is intended to be in place monitoring for 2 years.

The operating area of this expedition extends from Guam to Farrallon de Pajaros (Uracas).
The operating area of this expedition extends from Guam to Farrallon de Pajaros (Uracas).