Marine mammal visual and acoustic surveys near the Alaskan Colville River Delta

Information about the occurrence of marine mammals near the Colville River Delta (CRD), Beaufort Sea, Alaska is limited for most species expected to occur in this region. As part of marine mammal monitoring and mitigation for a seismic acquisition program August 25-September 30, 2014, we recorded marine mammal occurrence in a 30km(2) survey area between the Spy Islands and Oliktok Point near Simpson Lagoon using a combination of visual and acoustic monitoring methods. Visual effort totaled 632h, occurring 18-20h/day during all daylight hours by observers aboard three small survey vessels. In addition, an Inupiat observer and seal hunter from the village of Nuiqsut conducted a small-vessel survey to investigate locations of Phoca largha haul-out sites. A total of 102 individual marine mammals were recorded from five species: P. largha, Pusa hispida, Ursus maritimus, Erignathus barbatus, and Delphinapterus leucas. Over 400h of acoustic data were recorded using second-generation Ecological Acoustic Recorders deployed on the seafloor at three locations. Calls were identified for D. leucas, Balaena mysticetus, E. barbatus, and P. hispida. Results provide valuable information on marine mammal occurrence for the Beaufort Sea CRD during summer/fall, an area proposed for potential offshore oil and gas development