An Approach to Estimating Population Densities of Great Whales from Sighting Surveys

Estimates of population densities for great whales have been obtained from sighting surveys using line transect sampling and subsequent analysis based on the perpendicular distances of sightings from the trackline. This paper considers the use of a sighting process model to allow distances to sightings parallel to the trackline to be incorporated, in the hope of relaxing certain assumptions required by the usual line transect analysis. A number of theoretical and methodological problems with this approach and he conventional analysis are noted. An alternative sampling procedure is suggested which avoids many of these problems.