IMIS

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 Suckling. Purpose A 3-year survey began in 1997 to complete a new abundance estimate by 1999. This survey will also include an abundance estimate for Dall’s porpoise (Phocoenoides dalli). Once the 3 years of surveys are completed, the data will be used to estimate annual abundance of harbor porpoise and Dall’s porpoise, which is one of the key pieces of information needed to manage marine mammal-fishery interactions, as required under the Marine Mammal Protection Act.