NMML Small Cetacean (coastal) Aerial Survey 1997, Gulf of Alaska

Aerial surveys was conducted in 1997 progressing from east to west, to estimate abundance of the Southeast Alaska (SEA, 9,844 km survey effort), Gulf of Alaska (GOA, 10,127 km survey effort), and Bering Sea (BS, 7849 km survey effort) harbor porpoise stocks. In addition, 1355 km of survey effort during a Cook Inlet beluga survey were analyzed to add to the coverage for the GOA stock. Data from an independent observer concentrating on the trackline was used to estimate perception bias. Significant differences in g(0) and effective strip width (ESW) were found between the survey conducted in 1997 and the 1998 and 1999 surveys, therefore 1997 was treated separately. In both analyses, g(0) was dependent on visibility reported by observers, and in the 1997 data ESW was dependent as well. The 1997 survey included the inland waters of southeastern Alaska and the eastern Gulf of Alaska from Dixon Entrance to Cape Suckling1997年开展了自东向西的航空调查，旨在估算阿拉斯加东南部（Southeast Alaska, SEA，调查航程9844千米）、阿拉斯加湾（Gulf of Alaska, GOA，调查航程10127千米）以及白令海（Bering Sea, BS，调查航程7849千米）的港湾鼠海豚种群丰度。此外，本次研究还对库克湾白鲸调查中1355千米的调查航程数据进行分析，以扩充阿拉斯加湾种群的调查覆盖范围。研究采用专注于测线的独立观察员采集的数据来估算感知偏差。结果显示，1997年调查与1998、1999年调查在g(0)和有效条带宽度（effective strip width, ESW）上存在显著差异，因此将1997年的数据单独处理。在两项分析中，g(0)均与观察员报告的能见度显著相关；在1997年的调查数据中，有效条带宽度同样与能见度相关。1997年的调查范围涵盖阿拉斯加东南部内陆水域，以及从迪克森海峡到萨克林角的阿拉斯加湾东部海域。