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

Viktor Finnäs, Jan Olof Lill, Yvette Heimbrand, Martina Blass, Timo Saarinen, Yann Lahaye, Erkki Jokikokko, Henry Hägerstrand*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Micro X-ray fluorescence (µ-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 µ-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 µ-XRF mapped otoliths. In conclusion, µ-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.

Original languageEnglish
Pages (from-to)490-497
Number of pages8
JournalFisheries Management and Ecology
Volume27
Issue number5
DOIs
Publication statusPublished - 1 Oct 2020
MoE publication typeA1 Journal article-refereed

Keywords

  • Baltic Sea
  • elemental analysis
  • LA-ICP-MS
  • otolith
  • whitefish
  • µ-XRF

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