The current data suggests that Atlantic cod growth was not more rapid in the warmer period preceding the 17th century sea temperature minimum. In fact, growth in the 4th and 5th year of life was less rapid in AD 1570 (Table 2, Fig 3). This result may be consistent with previous research that show that adult growth is maximized at cooler sea temperatures [41, 57–59], as well as studies from the 20th century that have shown that warmer periods in Icelandic waters negatively impact cod, primarily through northward migrations of capelin; favored forage fish . Finally, the current growth reconstructions support that the large sized fish described in the medieval and early modern periods by anecdotes and archaeological reconstruction [1, 31] is not likely to represent a shift in growth patterns but the higher age of the pristine cod populations. Higher mean age of historical Atlantic cod populations has been found in previous studies [31, 37] and the current study (Table 1).