Micro-X-ray fluorescence image analysis of otoliths to distinguish between wild-born and stocked river-spawning whitefish captured in the Baltic Sea
Heimbrand Yvette; Hägerstrand Henry; Saarinen Timo; Lill Jan-Olof; Lindqvist Christer; Jokikokko Erkki; Finnäs Viktor
https://urn.fi/URN:NBN:fi-fe2022081154178
Tiivistelmä
Strontium concentrations are low in fresh waters compared to seawaters. Therefore, wild-born river-spawning and stocked freshwater-reared whitefish Coregonus lavaretus L. display regions with low concentrations of strontium in the centre of their otoliths. Strontium in otoliths from wild-born river-spawning whitefish ascending the River Tornionjoki, river-spawning whitefish stocked as one-summer-old fingerlings caught ascending the River Kemijoki, and sea-spawning whitefish caught near the Åland Islands was mapped using µ-XRF. The strontium-depleted regions in the centre of the whitefish otoliths, measured using ImageJ, had mean sizes of 0.18 ± 0.2 mm2 (River Tornionjoki) and 2.3 ± 0.3 mm2 (River Kemijoki), whereas the otoliths from whitefish caught at sea lacked a strontium-depleted region altogether. Measurement of the area of the strontium-depleted region in whitefish otoliths provides a convenient method with which to differentiate between whitefish of different provenance and to determine the origins of whitefish in mixed catches.
Kokoelmat
- Rinnakkaistallenteet [19207]