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News | May 11, 2009

Gulf of Alaska Marine Mammal Survey

By Naval Facilities Engineering Command, Southwest Naval Facilities Engineering Command, Southwest

Scientists with the U.S. Navy, National Oceanic and Atmospheric Administration's (NOAA) National Marine Mammal Laboratory (NMML) and Cascadia Research recently completed a marine mammal survey in the Navy's Gulf of Alaska training area. 

The team conducted the Gulf of Alaska Line-transect Survey, also known as GOALS 2009, April 10-20 aboard the NOAA research ship, Oscar Dyson. The Gulf of Alaska training area is a vast region of ocean encompassing 42,146 square nautical miles within the Northeast Pacific Ocean. This area holds high strategic value to the U.S. Navy due to its unique oceanographic conditions and proximity to military forces. 

Though historic whaling records have shown the occurrence of various marine mammals in this region, the current species composition and abundances are virtually unknown from this offshore area. With this in mind, GOALS 2009 was designed to fill in this gap of knowledge. 

During daylight hours, experienced visual observers from Cascadia Research and NMML stood rotating watches using high powered binoculars called "big eyes" through which marine mammals could be detected miles away. In addition, a passive acoustic array consisting of multiple hydrophones was towed along continuously listening and recording underwater sounds throughout the survey. Acoustic technicians from NMML, stood rotating four-hour watches to monitor the acoustic array. 

For 10 days, marine mammal observers visually spotted and counted eight species of cetaceans including humpback whales, fin whales, minke whales, gray whales, killer whales, Dall's porpoises, harbor porpoises and Pacific white-sided dolphins. In addition, the acoustic technicians detected and recorded sperm whales and killer whales. 

During the survey, the team was successful in approaching groups of killer whales for photographing the unique dorsal fin patterns to be used in cataloging individual whales. At the end of the cruise, the team transited through the Shumagin Islands, where they continued to survey for marine mammals outside of the Navy exercise area, en route to Dutch Harbor, the starting point of Oscar Dyson's next mission. 

The GOALS 2009 survey successfully gathered important data on the marine mammal species present in this largely unexplored area and provided information critical to assessing the environmental impacts of naval activities. These results will be presented to and shared with the scientific community at the biennial meeting of the Society of Marine Mammalogists in Quebec City in October.