Figure 8. Salmon δ15N plotted against zooplankton δ15N values. Each point represents an average value for a sockeye salmon stock that have been assessed to be distributed in the Gulf of Alaska. Zooplankton δ15N estimates were obtained from isoscapes presented in Espinasse et al., 2019.
Table 3. Trophic level estimates for nine salmon stocks assessed in this study to be distributed in the Gulf of Alaska during their last year at sea. The trophic level is based on the difference between δ15N values in salmon scales and large herbivorous copepods (TL 2) analyzed for this region, assuming a trophic level enrichment factor of 3.4‰.