Bias and variability in distance estimation on the water: implications for the management of whale watching. International Whaling Commission Meeting Document SC/52/WW1. (Available from http:// is.dal.ca/~whitelab/rwb/iwcvers.pdf

• Main Authors: Robin W. Baird, Stephanie M. Burkhart
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2000
• Subjects: Megaptera novaeangliae
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.172.1979; http://www.orcarelief.org/docs/baird_distance_estimation.pdf

Distance regulations or guidelines are the most common method used by regulatory agencies to manage interactions between whale watching vessels and whales. In Hawaiian waters, a distance rule prohibits vessels from approaching humpback whales (Megaptera novaeangliae) closer than 100 yards (91 m). Vessel captains and government enforcement agents rely almost entirely on estimating distance to whales, yet research on distance estimation abilities on land suggest a large degree of variability associated with such estimation. In 1999, we used laser range finders (accurate +/- 1 yard) to measure the distance between whale watching boats and whales, and obtained estimates of distances from vessel captains, naturalists, and members of the general public (702 estimate/measurement pairs from 106 individuals). We found a high degree of variability associated with distance estimation to whales on the water, more so than had been documented in land-based studies or controlled ship-based distance estimation experiments with highly experienced observers. A general bias towards under-estimating distance (ie., estimating that the vessels are closer to whales than they actually are) suggests that the distance rule is likely conservative, in terms of encouraging vessel operators to stay at least 100 yards from whales. Distance estimation abilities seem to improve with experience: estimates of vessel captains were less variable than estimates of naturalists or passengers. However, given the overall high degree of variability in estimating distance to whales, combined with the ease of use and relatively low cost of commercially available laser range finders, we suggest that such instruments should be incorporated into both whale watching and management of whale watching activities.