Fig. 3

Conceptual representation of the detection band for three acoustic receivers, each with a 1000-m effective tag-detection range, positioned in a linear array so as to form an “acoustic gate.” The series of concentric rings around the receivers represent bands that are 200 m wide, with shading around the leftmost receiver representing tag-detection probabilities that decrease with distance from the central receiver. Detection rings around the rightmost receiver have been omitted for clarity. The shortest possible pathway through the gate is indicated by the vertical dashed line (i.e., from arrowhead-to-arrowhead): the “Minimum Intersection Line,” which for a gate with a nominal bandwidth of 2000 m would be 1732 m in length