Effects of preservation by ethanol on ¹³C and ¹⁵N of three tissues of the critically endangered European eel Anguilla anguilla

The temporal effects of ethanol preservation on the delta C-13 and delta N-15 values of tissues excised from European eel Anguilla anguilla were assessed. Preservation significantly enriched C-13 values of fin and mucus but not dorsal muscle. The C-13 enrichment occurred in the initial 15 days of preservation and was independent of initial eel mass. Tissue preservation effects on delta N-15 values were negligible. These tissue-specific isotopic shifts should be considered when ethanol-preserved eel samples are used.