Atlantic cod growth has been examined across 20th century time series that have shown considerable short term and inter-annual fluctuations in growth [52, 53]. Archaeological datasets do not capture intra-annual or between cohort variation as cohorts and multiple years are inevitable pooled within a single archaeological deposit. The current results may therefore underestimate temporal fluctuations in growth and this is further indicated by the loss of any significant effects when the otoliths were pooled to three historical periods (S2 Table). However, the current data signals a notable decline in juvenile growth the 17th century. This is consistent with the results of Geffen et al.,  that showed decreased growth of north-east Arctic cod between the early 16th century and the 18th century. The current results add to those previously reported as they provide a second geographically distinct dataset and the temporal resolution of the current data allows further deductions on the timing and extent of growth shifts in Atlantic cod.