1 Survey design and applciation, 2 Visibility bias and missed observations, 3 Modeling.
J.L Laake (Alaska Fisheries Science Center, Settle) , D.G. Robertson (Western EcoSystems Technology Inc, Cheyenne, Wyoming, USA) , Steven C. Amstrup (Alaska Biological Science Center, US Geological Survey, Anchorage, Alaska), B.F.J Manly (Dept of Mathematics and Satistics, University of Otago, New Zealand).