The Fluorescent Mystery of European Glass Eels

Areas of Expertise: Fisheries and Aquatic Ecosystems

Service: Research & Development

Nature never ceases to amaze with its hidden colours, many of which are only revealed under ultraviolet (UV) light. UV biofluorescence—the ability of living organisms to absorb UV light and re-emit it as visible light—is a phenomenon found across a surprising array of species

In a world first, recent research by the eel team of AFBI Freshwater Fisheries has now discovered another participant in this phenomenon: the European glass eel (Anguilla anguilla).

European eels have been revealed to fluoresce under UV light emitting a distinct green glow. This finding suggests that biofluorescence may play a role in their underwater communication, camouflage, or perhaps predator-prey dynamics.

One highly useful application of our discovery is the detection of glass eels in the field. During our annual nighttime presence/absence monitoring of key recruitment sites throughout Northern Ireland, we have found that UV torches can make individual glass eels stand out at our estuarine sites. When dealing with small numbers of glass eels, particularly early in the year, the use of the UV torch helps us to detect and count glass eels more easily, which is otherwise more difficult under a regular white torch beam.

This finding serves as a reminder that even the most unassuming creatures can surprise us under the right wavelength.

Biofluorescence, it seems, continues to illuminate nature in more ways than one.

The full article was published in Aquaculture, Fish & Fisheries in Jun 2024