A comparison of recent changes in distribution of capelin (Mallotus villosus) in the Barents Sea, around Iceland and in the Northwest Atlantic

Capelin stocks in the Barents Sea, around Iceland and off eastern Newfoundland and Labrador have traditionally undergone similar basic migration patterns, from southern spawning sites to more northern feeding locations. In this paper, the migration and distribution patterns are reviewed for the three stocks. Special attention is paid to the relatively recent past, when Icelandic and Newfoundland/Labrador stocks exhibited changes in these patterns, while the Barents Sea stock did not undergo any significant distributional change. The changes occurred first off Newfoundland/Labrador and later in Icelandic waters. We examine the possible role of temperature and stock abundance in controlling capelin migration and distribution through comparisons of the three stocks. From the available observations, it is not possible to determine the relative impacts of temperature and abundance. However, all three areas have exhibited significant warming trend and we suggest that capelin may be reacting to large-scale ocean climate changes that have been occurring in the Arctic as a result of global warming. We speculate that such changes should appear first off Newfoundland/Labrador because this area is more heavily dominated by waters from the Arctic. In contrast, while both the Barents Sea and Icelandic areas are influenced by waters of Arctic origin, they also receive a significant input of warmer, Atlantic waters. The appearance of capelin in the Canadian Arctic is consistent with the movement towards the Arctic and/or an increase in abundance of a subarctic species previously at the margins of its historical distribution, under conditions of increasing ocean temperatures in the Arctic.