Modeling the distribution of the North Atlantic right whale Eubalaena glacialis off coastal Maine by areal co-kriging

Abstract

To enhance recovery of the Endangered North Atlantic right whale Eubalaena glacialis, mitigation strategies are needed to reduce the leading causes of injury and mortality of these animals, which include ship strikes and entanglement in fishing gear. Such efforts require information on the spatial and temporal distribution of right whales that can be analyzed against risk factors to identify solutions to protect whales while minimizing economic impacts to industry. Currently, no methods adequately make use of all available data to characterize right whale distribution, often leaving data gaps or misrepresenting whale activity in areas where we have limited systematic survey data. In response to this, an areal co-kriging interpolation technique was developed using ArcGIS 10.1 Geostatistical Analyst, utilizing all available right whale location data including systematic survey data, opportunistic sightings data, and satellite tag data. With many management plans shaped around specific geographic zones, this methodology was developed with the option to summarize information within user-defined polygons depending on the management regime. For this paper, whale distribution predictions were summarized to 524 irregularly shaped polygons off coastal Maine, representing lobster fishing zones at a 2 mo temporal scale. Results indicate that the predicted values fall within reasonable ranges, appropriately represent seasonal differences, and better represent right whale distribution patterns compared to other methods.