Fish fins and scales as non-lethally sampled tissues for stable isotope analysis in five fish species of north – eastern Spain
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White muscle has been traditionally used in determining δ 13C and δ 15N signatures in fish but ethics and the current conservation status of many species mean the application of non-lethal sampling procedures is mandatory. In this study we test whether fins and scales can be used as non-lethal alternatives of muscle tissue for stable isotope analysis by comparing their δ 13C and δ 15N signatures, in two native (Barbus haasi, Squalius laietanus) and three introduced fish species (Rutilus rutilus, Lepomis gibbosus and Alburnus alburnus), collected in rivers from north-eastern Spain. Our results showed fins and scales were generally enriched in 13C and depleted in 15 N compared to muscle, and that both tissues were generally a moderate predictor of the isotopic composition of muscle for most species with the exception of Ebro chub (R 2 = 0.59–0.97). This study highlights the importance of determining the isotopic relationship between lethal and non-lethally sampled tissues before making straightforward equivalences, and also pinpoints the need for a more comprehensive understanding of how isotopic discrimination occurs in fins, scales and muscle tissues.
Keywordsδ13C δ15N fish muscle non-lethal sampling correction factors
This work was supported by FURIMED-2, the Catalan Water Agency (ACA) and the Sabadell Town Council (“Parc Fluvial del Ripoll”). The study was authorized by the Autonomous Government of Catalonia (Generalitat de Catalunya) and fish were euthanized following the standard protocol established by the animal welfare service at the University of Barcelona. In addition, AMV and ADS performed a training course on the use of animals in research provided by the University of Barcelona. We thank M. Monroy, A. Canyelles and C. Cardoso for field work and P. Rubio for her assistance in stable isotope analyses at the “Serveis Cientifico-Tècnics” at the University of Barcelona, and M. Stremska for English revision. AMV was funded by a Marie Curie Fellow (EC-Funded ‘Para-Tox’ project n° 327941).
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