Visual surveys for cetaceans were conducted on the eastern Bering Sea shelf along transect lines, in association with the AFSC’s echo integration trawl surveys for walleye pollock. Surveys in 2000 and 2004 were from early June to early July, the survey in 2002 was from early June to late July, and the survey in 1999 was from early July to early August. Searches for cetaceans were conducted from the flying bridge of NOAA Ship Miller Freeman at a platform height of 12 m above the sea surface and survey speed of 18.5 22.0 km/h (10 12 kts). North south transect lines were spaced 37 km apart and defined by the historical acoustic survey for walleye pollock. Insufficient funding precluded including cetacean observers on all legs except in 2002. See Friday et al. 2012. Cetacean distribution and abundance in relation to oceanographic domains on the eastern Bering Sea shelf: 1999-2004 (http://www.sciencedirect.com/science/article/pii/S0967064512000100).

In 1991, NMML initiated cetacean studies with vessel coverage throughout inland waters of Southeast Alaska. Between 1991 and 1993, line-transect methodology was used to: 1) obtain population estimates of both harbor porpoise and Dalls porpoise, 2) establish a baseline for detecting trends in porpoise abundance, and 3) define porpoise distributional patterns and seasonality. Three line-transect surveys were carried out each year spanning spring, summer, and fall. To update abundance and trends for both harbor porpoise and Dalls porpoise, NMML once again initiated line-transect surveys in 2006 (spring and summer), 2007 (spring, summer and fall), 2010 (summer and fall), 2011 (summer and fall), and 2012 (summer) using methods comparable to those used in the early 1990s.

This dataset contains vessel- and aircraft-based mammal sightings data and associated environmental data collected in the Chukchi and Beaufort seas during the open water season 2006-2010. The aerial data are derived from marine mammal observers aboard aircrafts flown at 1000 ft to 1500 ft. The data contains marine mammal sightings data and associated environmental data collected during the open water season 2006-2010 (excluding 2009) in Chukchi Sea and Beaufort Sea. In addition, this metadata describes aerial navigational GPS data recorded during observations. Data collection methods changed slightly between years. The metadata for each attribute should be studied carefully before these data are used for analyses.