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Tracking long‐distance migration of marine fishes using compound‐specific stable isotope analysis of amino acids
Author(s) -
Matsubayashi Jun,
Osada Yutaka,
Tadokoro Kazuaki,
Abe Yoshiyuki,
Yamaguchi Atsushi,
Shirai Kotaro,
Honda Kentaro,
Yoshikawa Chisato,
Ogawa Nanako O.,
Ohkouchi Naohiko,
Ishikawa Naoto F.,
Nagata Toshi,
Miyamoto Hiroomi,
Nishino Shigeto,
Tayasu Ichiro
Publication year - 2020
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1111/ele.13496
Subject(s) - trophic level , isotope analysis , stable isotope ratio , δ15n , food web , oncorhynchus , isotope , ecology , proxy (statistics) , oceanography , pacific ocean , biology , environmental science , fishery , geology , δ13c , fish <actinopterygii> , physics , quantum mechanics , machine learning , computer science
The long‐distance migrations by marine fishes are difficult to track by field observation. Here, we propose a new method to track such migrations using stable nitrogen isotopic composition at the base of the food web ( δ 15 N Base ), which can be estimated by using compound‐specific isotope analysis. δ 15 N Base exclusively reflects the δ 15 N of nitrate in the ocean at a regional scale and is not affected by the trophic position of sampled organisms. In other words, δ 15 N Base allows for direct comparison of isotope ratios between proxy organisms of the isoscape and the target migratory animal. We initially constructed a δ 15 N Base isoscape in the northern North Pacific by bulk and compound‐specific isotope analyses of copepods ( n = 360 and 24, respectively), and then we determined retrospective δ 15 N Base values of spawning chum salmon ( Oncorhynchus keta ) from their vertebral centra (10 sections from each of two salmon). We then estimated the migration routes of chum salmon during their skeletal growth by using a state‐space model. Our isotope tracking method successfully reproduced a known chum salmon migration route between the Okhotsk and Bering seas, and our findings suggest the presence of a new migration route to the Bering Sea Shelf during a later growth stage.