Silver hake tracks changes in Northwest Atlantic circulation

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Recent studies documenting shifts in spatial distribution of many organisms in response to a warming climate highlight the need to understand the mechanisms underlying species distribution at large spatial scales. Previous work documented the remote oceanographic processes governing the spatial distribution of adult silver hake, Merluccius bilinearis, a commercially important fish in the Northeast US shelf region. Changes in spatial distribution of silver hake over the last 40 years are highly correlated with the position of the Gulf Stream (GS). Silver hake shifted their spatial distribution in direct response to local changes in bottom temperature on the continental shelf that are responding to the same large scale circulation change affecting the GS path, namely changes in the Atlantic Meridional Overturning Circulation (AMOC). Further analysis illustrates that other species also respond to this remote forcing, suggesting that the GS position is the best leading indicator of thermal conditions resulting in ecosystem change on the shelf. If AMOC weakens as is suggested by global climate models, silver hake and other species will remain in a poleward position, the extent to which could be forecast at both decadal and multidecadal scales.