Detection Probability Estimates from Ice-Based Surveys of Bowhead Whales Near Barrow, Alaska, Using a Weighted Recapture Model

• Activity Number: 233
• Type: Topic Contributed
• Date/Time: Monday, August 5, 2013 : 2:00 PM to 3:50 PM
• Sponsor: Section on Statistics and the Environment
• Author(s): Geof Givens*+ and Stacy Edmondson and Craig George and Barbara Tudor and Rob DeLong and Robert Suydam
• Companies: Colorado State University and Colorado State University and North Slope Borough, Alaska, Dept. of Wildlife Management and North Slope Borough, Alaska, Dept. of Wildlife Management and DeLongView Enterprises and North Slope Borough, Alaska, Dept. of Wildlife Management
• Keywords: mark-recapture ; independent observer ; sight-resight ; wildlife population abundance

Abstract

We describe estimation of visual detection probabilities from two-perch ice-based independent observer surveys of bowhead whales near Barrow, Alaska, in spring 2010 and 2011. Standard capture-recapture methods are not directly applicable because of sighting ambiguities, match uncertainty and group size inconsistencies introduced by the survey protocol. We develop several bias correction methods that are essential to produce accurate estimates. Then we adapt the general capture/recapture model of Huggins (1989) to formulate a weighted data analysis approach. This model estimates the relationship between detection probabilities and covariates associated with the sighting, including sighting distance, ice conditions and whale group size. Considerations of results, sensitivities and implications conclude the talk.