The Science

Peer-reviewed research is the foundation of everything we build.

1. Eel are in crisis

The European eel (Anguilla anguilla) is critically endangered. The American eel (Anguilla rostrata) and Japanese eel (Anguilla japonica) are also Endangered.

Since the 1980s, recruitment has declined by up to 99% in some areas. Hydroelectric dams, pumping stations, and sluices kill out-migrating silver eel — and these losses are especially costly because eel spawn only once, at the end of their lives.

Cumulative mortality at two hydropower dams on the St. Lawrence River alone is estimated at 39.5%.

See how we address this →

2. Silver eel avoid light

Peer-reviewed research has established that silver eel are negatively phototactic — they avoid light.

In a controlled laboratory study at the University of Southampton:

Eel were significantly less likely to select a lit channel
They rejected it more strongly at higher light intensities

Vowles, A.S. & Kemp, P.S. (2021). Artificial light at night (ALAN) affects the downstream movement behaviour of the critically endangered European eel, Anguilla anguilla. Environmental Pollution, 274, 116476.
View the paper →

In flume studies:

Eel chose the darkened corridor over the illuminated one
Blue (480 nm) and white light elicited the strongest avoidance
This matches the eel's retinal sensitivity, which shifts to blue-green as they mature for ocean migration

Key finding: Light is a repellent, not an attractant, for silver eel.

3. Field-scale evidence

The largest field experiment to date was conducted at the Iroquois Water Control Dam on the St. Lawrence River, Canada — a 774-metre-wide channel with flows of 0.6 to 1.5 m/s.

Method:

398 eel tagged with acoustic transmitters
216-metre floating light array with downward-facing white LEDs
27 acoustic receivers tracking movement in 3D
Control nights (lights off) vs. treatment nights (lights on)

Findings:

96% of eel migrated at night, concentrated during waning moons
Eel exposed to light slowed down, dove deeper, and altered swim speed
The effect was strongest within 25 metres of the array
Detectable influence extended to 51 metres
Eel generally swam in the upper 3 metres of the water column — not near the bottom

Critical finding: Eel responded to light by diving, not by deflecting horizontally.

MacLeod, M.E.C. (2024). Characterizing American Eel Out-Migration and their Vertical Movement Responses to an LED Behavioural Guidance Device. MSc thesis, Carleton University.
View the thesis →

This is the most important result for our work — and for the field as a whole.

4. What this means for guidance

The science confirms that light changes eel behaviour. But it also shows that the response is not yet fully predictable.

Eel dive when lit. Whether that diving can be harnessed to guide them toward safety — rather than simply downward — is the open question our work addresses.

This is why our systems are tunable and site-calibrated. No single configuration works everywhere. The light must be tuned to the site, the flow, and the eel population.

See our approach →

5. What we are testing

Our research and development focuses on:

Wavelength — blue (480 nm), white, and other spectra
Intensity — strong enough to deflect, tuned to the site
Pulse rate — constant vs. strobed vs. pulsed
Geometry — bar, hose, or array, matched to the structure
Position — in-water vs. above-water lighting
Flow interaction — how flow speed affects response
Species selectivity — repelling eel without attracting other species

Read our FAQ →

6. What the research does not yet show

We are honest about the limits:

No study has yet demonstrated reliable horizontal deflection of eel at high-flow hydropower intakes
No current technology protects light-attracted species (baitfish, glass eel, squid) at high-flow sites
Sound, flow, and electrical guidance are not yet viable as standalone methods
Every site behaves differently — there is no out-of-the-box solution

Our approach: build tunable hardware, validate at real sites with research partners, publish the data, and improve with each installation.

7. The research community

We work within the international network studying this problem:

Eel Passage Research Centre (EPRC) — a bi-national group of biologists from EPRI, Fisheries and Oceans Canada, Hydro Québec, New York Power Authority, Ontario Ministry of Natural Resources and Forestry, US Fish and Wildlife Service, and others
Visit EPRI →
Carleton University — Cooke Lab, where the St. Lawrence field study was conducted
Visit Carleton University →
University of Southampton — Vowles & Kemp, who established the light avoidance mechanism
Visit University of Southampton →
Wageningen Marine Research — our European research partner
Visit Wageningen →

Independent validation is essential. It gives water authorities and grant programs confidence that the system works — not just that we say it does.

Work with us →

References

Vowles, A.S. & Kemp, P.S. (2021). Artificial light at night (ALAN) affects the downstream movement behaviour of the critically endangered European eel, Anguilla anguilla. Environmental Pollution, 274, 116476.
View the paper →
MacLeod, M.E.C. (2024). Characterizing American Eel Out-Migration and their Vertical Movement Responses to an LED Behavioural Guidance Device. MSc thesis, Carleton University.
View the thesis →
MacLeod, M.E.C., Pratt, T.C., Elvidge, C.K., & Cooke, S.J. Reviewing the Potential for Behavioural Guidance to Improve Downstream Passage of Out-Migrating Anguillid Eels. (In submission, River Research and Applications.)

MacLeod-2024-American-Eel-LED-Guidance.pdf

AnguillaLight — Guiding eel with light.