ACKNOWLEDGEMENTS
We thank I. Itoh and C. Kamata at the Tohoku National Fisheries Research Institute for the preparation of copepod samples; C. Yoshimizu at the Research Institute for Humanity and Nature for stable isotope analysis of bulk tissues; A. Matsuda and T. Kawakami at the University of Tokyo and K. Nakata and S. Yoshimasu at the Japan Fisheries Research and Education Agency for providing salmon samples for analysis; Y. Takano and T. Blattmann for their helpful comments on the draft of the paper; the Foundation for the Japan Science and Technology Agency Core Research for Evolutional Science and Technology (JST CREST) Grant JPMJCR13A4 and JPMJCR13A3; the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant 17J04991 and 19K20495 to J.M.; and the Arctic Challenge for Sustainability (ArCS) Project, and Tohoku Ecosystem-Associated Marine Sciences (TEAMS) Program, which were funded by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT).