Differences in diving and movement patterns of two groups of beluga whales in a changing Arctic environment reveal discrete populations

Abstract

Harvest and global climate change are among the major ongoing threats to most Arctic marine mammal populations. Affected by commercial hunting in the past, beluga whales Delphinapterus leucas are still harvested for subsistence in many coastal areas of the Canadian Arctic, while ongoing climate changes are suspected to modify factors that may have determined the distribution and degree of interaction of the different populations. Although several populations have been clearly identified, the global discreteness of the Arctic metapopulation is not yet clearly established. In this study, seasonal diving activity and movement patterns of 46 belugas from 2 neighbouring groups in Hudson Bay (Canada) were analysed in relation to physical environmental characteristics and revealed significantly different migratory and habitat use patterns. Likely affected by local environmental conditions, the Eastern Hudson Bay beluga migrate, while the James Bay beluga remain resident, suggesting little overlap between the groups at all times of the year. This study provides useful baseline data for determining population interactions and habitat use. The information is also potentially useful in identifying critical habitat, which is an essential component to design and implement management and conservation policy, e.g. quota and harvesting regulations and the design of marine protected areas.