a decreasing trendp<0.001
Overall, there was a decreasing trend in δ 13 C oto over the last century (main Year effect p<0.001), with a larger decrease observed in Icelandic cod (mean values of δ 13 C oto decreased by 0.7‰ over the past 100 years) compared to NEA cod (mean values decreased by 0.3‰ over the past 100 years) ( Table 2 , Fig 3 ).