Response: Demography affects spawning location in Northeast Arctic cod, but what affects demography?

In a letter to the editor, Sundby (2015) expresses concerns about our study of changing spawning locations of the Northeast Arctic (NEA) stock of Atlantic cod over the period 1866–1969, where we identified statistically significant effects of the stock’s demography whereas various climate indices all fell below statistical significance. Our conclusion on the role ascribed to climate disagrees with that of Sundby & Nakken (2008), which, based on a subset of our data and without considering demography, concluded that spawning was shifted northwards in warm periods. Sundby’s (2015) criticism boils down to four points that we will address in turn.