Towards a more balanced assessment of the dynamics of North Atlantic ecosystems - A comment on Drinkwater and Kristiansen (2018)

Drinkwater and Kristiansen (hereafter D&K) (2018, A synthesis of the ecosystem responses to the late 20th century cold period in the northern North Atlantic, ICES Journal of Marine Science, 75: 2325-2341) examined multi-trophic level biological responses in relation to a 1960s-1980s "cold period" that they associated with the Atlantic Multidecadal Oscillation (AMO). They concluded that ocean temperature was a major driver of ecosystem changes throughout the North Atlantic during this interval and adversely affected the abundance, spawning stock biomass (SSB), recruitment, survival success of several species including cod in four North Atlantic ecosystems (NE Arctic, Iceland, West Greenland, and Labrador-northern Newfoundland). D&K further suggested that negative ocean temperature anomalies during this cold period occurred first in the Eastern Arctic and Barents Sea, propagated westward across the North Atlantic to the Labrador Sea and were potentially related to a sequential E-W collapse of the four cod stocks. We take issue with these conclusions and suggest that a more quantitative discussion of fisheries exploitation was in order.