Second, as there were often few otoliths in each archaeological deposit, we divided the otoliths into three non-overlapping temporal groups, the first represented samples dated to before AD 1499 (Medieval period), the second group included samples dated to AD 1500—AD 1784 (Early Modern period) and finally samples dated to post AD 1785 (Modern period). This classification represents a common historical designation of periods. We then repeated the GLMM, as described above, but replacing archaeological deposit with period as a fixed effect.