PRIMARY RESEARCH PAPER Development of non-lethal monitoring of stable isotopes in asp (Leuciscus aspius): a comparison of muscle, fin and scale tissues M. Vasˇek . L. Vejrˇı ´k . I. Vejrˇı ´kova´ . M. S ˇ mejkal . R. Baran . M. Musˇka . J. Kubecˇka . J. Peterka Received: 7 April 2016 / Revised: 28 July 2016 / Accepted: 30 July 2016 / Published online: 13 August 2016 Ó Springer International Publishing Switzerland 2016 Abstract We explored whether fin clips and scales can be used as potential non-lethal alternatives to muscle tissue for examining the isotopic composition of asp Leuciscus aspius, a locally threatened freshwa- ter species. Dorsal fin clips, scales and muscle plugs were collected from two asp populations and subse- quently analysed for nitrogen and carbon stable iso- topes. Both fins and scales were consistently depleted in 15 N and enriched in 13 C relative to muscle. A linear regression found that the isotope values in asp fins and scales were significantly related to those in the muscle tissue. These results indicate that fins and scales have the potential to be a substitute for muscle in stable iso- tope studies of asp, thus providing a non-destructive sampling method for this species. Nevertheless, to determine reliable conversion factors between tissues, a subset of individuals covering a sufficiently wide range of body sizes may need to be sacrificed for any given population. Keywords Fin clips  Fish scales  Fractionation  Non-lethal sampling  Stable isotopes  Threatened species Introduction Naturally occurring stable isotopes, especially those of carbon and nitrogen, are now routinely used in studies of aquatic food webs. The most common applications of stable carbon and nitrogen isotope measurements are to determine trophic interactions among organisms (Clarke et al., 2005; McIntyre et al., 2006; Hayden et al., 2014), to quantify energy flow through ecolog- ical communities (Vander Zanden et al., 1999; Finlay et al., 2002; Karlsson & Bystro¨m, 2005), to trace nutrient pollution (Schlacher et al., 2005; Anderson & Cabana, 2006; Xu & Zhang, 2012) and to predict contaminant bioaccumulation (Cabana & Rasmussen, 1994; Kidd et al., 2001). For fish, dorsal white muscle has been the tissue traditionally used in stable isotope analyses (Pinnegar & Polunin, 1999). However, sampling of muscle tissue is usually destructive and requires killing the fish. Lethal research sampling causes ethical issues and should be avoided, especially in cases of endangered and locally rare species or populations of exceptional value. Hence, to eliminate Handling editor: M. Power M. Vasˇek (&)  L. Vejr ˇı ´k  I. Vejrˇı ´kova´  M. S ˇ mejkal  R. Baran  M. Musˇka  J. Kubecˇka  J. Peterka Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sa´dka´ch 7, 370 05 C ˇ eske´ Budeˇjovice, Czech Republic e-mail: mojmir.vasek@seznam.cz L. Vejrˇı ´k  I. Vejrˇı ´kova´ Faculty of Science, University of South Bohemia, Branisˇovska´ 31, 370 05 C ˇ eske´ Budeˇjovice, Czech Republic 123 Hydrobiologia (2017) 785:327–335 DOI 10.1007/s10750-016-2940-2