Migration route and seasonal home range of the northern hudson bay narwhal (monodon monoceros)

Abstract

The northern Hudson Bay narwhal (Monodon monoceros) population gathers in the area of Repulse Bay, Nunavut in the summer season. This population is hunted by local Inuit and co-managed by the Nunavut Wildlife Management Board and the Department of Fisheries and Oceans. There is some uncertainty as to the size of the population, the migration route this population takes to its wintering areas, if its winter range overlaps with that of other narwhal populations, and whether it is hunted by other communities during migrations. In the face of a changing climate, this ecological information is essential to understanding the success of the population in the future. The main focus of this paper is to provide summer and winter home range data of narwhals, as well as migration routes. This in turn will help to determine if past aerial surveys covered appropriate areas and what boundaries should be considered for future aerial population surveys. Ultimately this information will contribute to written documentation of traditional ecological knowledge and may assist in determining if this population is a separate stock. Finally, this study establishes a baseline to evaluate future impacts of climate change on this Hudson Bay narwhal population. Nine narwhals were tagged with satellite-linked tracking devices in August 2006 and 2007 in the vicinity of Repulse Bay, Nunavut. Whales were tracked using the ARGOS system for 100 to 305 days with two of the tags transmitting long enough to show the beginning of the migration from wintering areas back to summer areas in early May. The trajectories of the tagged narwhals were estimated from the ARGOS locations using a movement state-space model. Home range size for each data set was calculated using 95% and 50% kernel estimates. In addition, 17 hunters and elders were interviewed in the community of Repulse Bay in order to gather traditional ecological knowledge of the species to add to the scientific analysis. Results of local and scientific knowledge suggest that a portion of the summer home range falls to the east of past aerial survey coverage and that winter range does not overlap with that of other narwhal populations. Migration route of tracked animals coincide with traditional ecological knowledge of narwhal migration and suggests that this population is probably rarely hunted by other communities en-route between summer and winter areas. © 2010 Springer Netherlands.