Commission). We are very grateful to Andrew A. Scha ner for excellent research assistance. We thank Dr. Thomas F. Albert, Craig George and other scientists and personnel from the Borough's Department of Wildlife Management, the many other researchers with whom we have worked, most of whose names appear on papers in our reference list, the census crew, and the Eskimo hunters of the Borough, for their contributions to our understanding of bowhead whales and the census. We are also grateful to Geof Givens for useful discussions, and to Doug Butterworth and Andre Punt Estimating the population size and rate of increase of bowhead whales, Balaena mysticetus, is important because bowheads were the rst species of great whale for which commercial whaling stopped and so their status indicates the recovery prospects of other great whales, and also because this information is used by the International Whaling Commission (IWC) to set the aboriginal subsistence whaling quota for Alaskan Eskimos. We describe the 1993 visual and acoustic census o Point Barrow, Alaska, which provides the best data available for estimating these quantities. We outline the de nitive version of two statistical methods for estimating the population, the generalized removal method and the Bayes empirical Bayes

This document represents National Marine Fisheries Service’s biological opinion (Opinion) on the Minerals Management Service’s (MMS) proposed approval of a development and production plan for the construction and operation of the Liberty project in the U.S. Beaufort Sea off Alaska’s north coast, and its effects on the endangered bowhead whale, Balaena mysticetus, in accordance with section 7 of the Endangered Species Act of 1973, as amended (ESA) [16 U.S.C. 1531 et seq.]. Formal section 7 consultation with the MMS was initiated on March 2, 2001. This Opinion is based on information provided by the MMS in their Draft Environmental Impact Statement (DEIS) on the Liberty Development and Production Plan released in January 2001, the biological assessment dated February 26, 2001, recent research on the effects of oil and gas activities on the bowhead whale, traditional knowledge of Native hunters and the Inupiat along Alaska’s north slope, and other sources of information. A complete administrative record of this consultation is on file at the NMFS ’ Alaska