Low microplastic loads in riverine European eel (Anguilla anguilla) from southwest England during their marine-freshwater transition.

The microplastic loads in elvers of the critically endangered European eel Anguilla anguilla, sampled in the lower reaches of three English rivers, were very low (incidence: 3.3%, mean ± s.d.: 0.03 ± 0.18 particles) and did not vary with body length or between rivers. Particles were mostly black, polyolefins, fibres and fragments of size 101-200 µm. Current levels indicate a low contamination pressure locally and, consequently, management efforts might prioritise mitigating the effects of other stressors affecting the species.

Effects of preservation by ethanol on δ13 C and δ15 N of three tissues of the critically endangered European eel Anguilla anguilla.

The temporal effects of ethanol preservation on the δ13 C and δ15 N values of tissues excised from European eel Anguilla anguilla were assessed. Preservation significantly enriched 13 C values of fin and mucus but not dorsal muscle. The 13 C enrichment occurred in the initial 15 days of preservation and was independent of initial eel mass. Tissue preservation effects on δ15 N values were negligible. These tissue-specific isotopic shifts should be considered when ethanol-preserved eel samples are used.

Non-lethal sampling for the stable isotope analysis of the critically endangered European eel Anguilla anguilla: how fin and mucus compare to dorsal muscle.

Ecological studies on the critically endangered European eel Anguilla anguilla often incorporate stable isotope analysis that typically uses dorsal muscle sampled from euthanised eels. To minimise the lethal sampling of imperilled populations, fin tissue and/or epidermal mucus can provide non-lethal alternatives to muscle. The results here indicate that δ13 C and δ15 N values of both eel fin and mucus are not significantly different from those of muscle and can be applied directly in comparative SI studies.