Method for estimating sperm whale abundance from an acoustic strip transect survey with a two-element towed hydrophone

A method for estimating sperm whale abundance in an acoustic line-transect survey with a two-element hydrophone is described. The analysis starts from the point where set of click trains have been identified by analyst. Using likelihood methods, description given estimation each train (i) positions bearing patterns trains, (ii) most likely numbers whales aggregations and (iii) radial detection function based on times detected clicks estimated position. uses complete allowable arrangements these into different whales. number potentially very large yet can be computed because many combinations are not permissible, e.g. overlapping cannot same whale. It suggested that could work well over perpendicular distances near-certain i.e. strip transect survey. applied to data western Mediterranean. Simulations support width 5km. Some shortcomings areas further development discussed.