LASER‐METRICS OF FREE‐RANGING KILLER WHALES

Data on morphometrics are central to understanding key features of both population and behavioral ecology, including phenotypic differences between species (Perryman and Lynn 1993, Meijaard and Groves 2004) and populations (Perryman and Lynn 1994), life history traits such as patterns of individual growth (Read et al. 1993, Lee and Moss 1995), and morphological differences related to mating systems (Boonstra et al. 1993, Tolley et al. 1995, Plavcan and van Schaik 1998). In the marine environment, it has proved difficult to obtain measurements from free-ranging cetaceans. Capture operations can yield precise data on morphometrics (e.g., Read et al. 1993), but such disruptive procedures are generally not feasible and are restricted to smaller species. On a more remote level, photogrammetric approaches have been successfully applied to estimate body size from aerial platforms (e.g., Perryman and Lynn 1993) and from underwater images (Klimley and Brown 1983, Spitz et al. 2000), but stereophotogrammetric methods require a camera configuration that is somewhat cumbersome (Klimley and Brown 1983, Brager et al. 1999, Brager and Chong 1999), and can be difficult to implement from small-boat research platforms alongside routine data collection. We describe a simple approach for obtaining morphometric measurements based on photographing two laser dots that have been projected onto the body of a whale using two small laser-pointers. These laser-pointers are mounted in a parallel orientation to maintain a fixed and known separation distance, and the dots therefore provide a scale of known dimension on the image of the whale that can be used to calibrate morphometric measurements. The lightweight laser setup can be conveniently mounted on a camera lens, allowing this approach to be implemented by a single photographer in conjunction with photo-identification studies. We demonstrate the