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Research article - Peer-reviewed, 2020

Prevalence of stocked whitefish in River Kemijoki, Finland, inferred by micro X-ray fluorescence analysis of otoliths

Finnas, Viktor; Lill, Jan-Olof; Heimbrand, Yvette; Blass, Martina; Saarinen, Timo; Lahaye, Yann; Jokikokko, Erkki; Hagerstrand, Henry


Micro X-ray fluorescence (mu-XRF) analysis of otoliths was evaluated as a method to estimate the proportion of stocked one-summer-old whitefish Coregonus lavaretus L. in catches of adult fish (n = 20) ascending the River Kemijoki to spawn. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis was applied as control. Polished otoliths were scanned with mu-XRF to obtain strontium maps that were used to infer visually the provenance of the whitefish. Thirteen of the fish showed signs of being stocked as one-summer-old fingerlings. LA-ICP-MS was applied to determine the elemental composition in a spot outside the core of the otolith. The results were largely consistent with the visual inspection of the mu-XRF mapped otoliths. In conclusion, mu-XRF mapping successfully identified whitefish stocked as one-summer-old fingerlings. The vast majority of whitefish returning to the River Kemijoki to spawn were stocked fish.


mu-XRF; Baltic Sea; elemental analysis; LA-ICP-MS; otolith; whitefish

Published in

Fisheries Management and Ecology
2020, volume: 27, number: 5, pages: 490-497
Publisher: WILEY

Authors' information

Finnas, Viktor
Abo Akad Univ
Lill, Jan-Olof
Abo Akad Univ
Swedish University of Agricultural Sciences, Department of Aquatic Resources
Swedish University of Agricultural Sciences, Department of Aquatic Resources
Saarinen, Timo
Univ Turku
Lahaye, Yann
Geol Survey Finland
Jokikokko, Erkki
Nat Resources Inst Finland LUKE
Hagerstrand, Henry
Novia Univ Appl Sci

UKÄ Subject classification

Fish and Aquacultural Science

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