Marine climate, squid and pilot whales in the northeastern Atlantic

We have identified a clear link between the abundance of longfinned pilot whales and the marine climate in the northeastern Atlantic throughout the last three centuries. During warm periods the whales are observed in high abundances and they can be completely absent from the region during cold periods. The linkage between the marine climate and the abundance of whales probably involves their main prey items, flying squid (Todarodes sagittatus) and the large, but highly variable blue whiting (Micromesistius poutassou) stock. The latter is preyed upon both by the squid and the whales. The subpolar gyre declined drastically in the late 1990s, resulting in warming and a great increase and a westward shift of the blue whiting stock, but the abundances of T. sagittatus and pilot whales in Faroese waters did not increase correspondingly. The post-1980s breaking of this, otherwise stable, multi-century bio-physical link points to anthropogenic interference. We discuss potential causes, rooted in Global Warming and an intensified pelagic fishery, which collectively might explain this breaking relation. Some new aspects of sub-decadal variability in the marine climate and in the Faroe shelf ecosystem are introduced.