Using an LED-Based Light to Guide Fish Behavior

The authors have developed a new light-emitting diode (LED) light system that uses red, green and blue light modules – at different frequencies and in different combinations – to guide fish behavior around hydro intakes. Research results indicate different responses based on fish species and age.

By Paul H. Patrick and A. Michael Sills

Lights have been studied for application in fish protection projects at hydroelectric and once-through cooling power plants for many years. Earlier studies focused on “white” light or specific types of light projectors such as halogen, mercury vapor and strobe lights. Most of these devices are limited in that there is little or no flexibility in adjusting light spectrum or wavelength, as well as light intensity, within the same device. However, this flexibility is required because species-specific responses to light do occur, which can vary diurnally as well as seasonally with fish ontogenetic development.

There are still several examples where “white” strobe light or mercury vapor light have been effective as a repellant or attractant for some fish species.1,2,3,4,5,6,7 Still, white strobe light does not appear to have potential for widespread application at water intakes for all fish species given species-specific responses.8 Similarly, light – both constant and flashing – has promise for fish protection and passage, but spectrum-specific differences in fish response, the effects of background and contrast and other aspects require further investigation.5

There are differences in the spectral sensitivities of retinal cone cells in different fish species, which should result in a stronger response when subjected to selected frequencies of light as opposed to a broad spectrum white light. For example, a review of the existing literature on the visual ecology of adult Atlantic eels, based largely on laboratory in vivo sensory physiology experiments, during spawning migration revealed that they have strong retinal sensitivies to blue (480 nm) and green (520 nm) light, with the blue sensitivity developing concurrent with sexual maturation.

There is a need to address species-specific responses, and with development of LED (light-emitting diode) technology, a wider range of light spectra are available for different species assessments.

An alternative approach

The Light Guidance Device (LGD) is a U.S.-patented underwater LED device with red, green and blue light modules ATET-Tech developed to address species-specific responses to light. It is software-controlled, which allows the user to produce different color combinations of constant or flashing light at frequencies of 1 to 40 times per second to address species-specific responses of fish and other aquatic organisms. The LGD can either be used alone for fish protection or integrated with another system used to modify fish behavior through repulsion (i.e., movement away from an intake) or attraction (i.e., movement toward a bypass).

Various spectral and wavelength combinations produced by the device are proving to be effective at attracting or repelling juveniles of a wide variety of fish species. Laboratory and field tests conducted by Carleton University in Ottawa, Canada, and the University of California at Davis have supported development of established databases for lake sturgeon, white sturgeon, American eel, walleye, largemouth bass, sea lamprey and chinook salmon.

Results for most of these species have been published in scientific journals or reports, and the highlights of this research are summarized in Table 1.

The LGD has shown promise for both attraction and repulsion, which does vary with species and size or age of fish tested. For example, for lake sturgeon, there is strong evidence for ontogeny of blue light avoidance. Juvenile fish tend to be attracted by blue light but tend to avoid this wavelength as they develop into adults. This has important management implications to use the appropriate wavelength depending on the life stage of the migrating individuals of a given species and the time of year. For example, juvenile sturgeon likely migrate at different times than adult fish, allowing different wavelengths to be used for either attraction or repulsion purposes.

Integrated systems

Lights and other non-physical barriers may be more effective when used in combination with other fish diversion systems.9 This can include fish pumps, bar racks, angled screens, louvers and fish guidance systems.10 Integrated systems may be necessary at some hydroelectric facilities given the well-documented species-specific responses to different stimuli (e.g. water velocity, light and sound levels), the plasticity of diel patterning and circadian rhythms in fish in response to changing light cues, and the influence of various environmental parameters such as temperature and turbidity on the performance of fish protection systems. Well-designed integrated systems should be developed to address both the requirements of different species as well as different life history stages within species, notably between juvenile and adult fish.

An example of an integrated system is using a series of LGDs behind a bar rack (or louver) to guide fish toward a bypass away from the turbines. In this case, a traditional bar rack may be angled 90 degrees to the flow to improve fish diversion. As an integrated system, the LGDs would be used for guidance along the bar racks as a possible attractant towards a bypass (it is also possible for repulsion wavelengths to be used at specific locations behind the angled screen or louver array to increase fish passage effectiveness).11,12 The use of specific wavelengths for fish guidance is expected to allow increased spacing and greater array angle of the louver slats, requiring less material, lower construction costs, improved hydraulic performance and decreased incidence and severity of biofouling. Avoidance behavior of brown trout encountering accelerating flow is enhanced with lights, and downstream moving fish avoidance behavior can be improved when a combination of stimuli are presented, such as the use of lights with louvers.13

The next steps are to evaluate the LGD technology in the field; specifically to improve downstream fish movement away from turbines and toward a fish bypass. We also need to measure the spectral output of the LGD in the field, especially for different water bodies. In addition, LGD could be tested as an attractant to improve fish passage at upstream facilities. These tests will be necessary to understand the full usefulness of this tool.

Acknowledgments

Special thanks to Dr. Steve Cooke and his students at the Fish Ecology and Conservation Physiology Laboratory (Cooke Lab), Carleton University, especially Dr. Chris Elvidge, as well as Matt Ford, Connor Reid and Brittany Sullivan. Also, we would like to thank Dr. Nann Fangue and Dr. Matt Hansen at the Department of Wildlife, Fish and Conservation Biology, University of California at Davis, for their work currently in progress. These universities provided the technical data on the responses of different fish species to the LGD.

Notes

1Haymes, G.T., P.H. Patrick, and L.J. Onisto, “Attraction of Fish to Mercury Vapour Light and Its Application in a Generating Station Forebay,” International Review of Hydrobiology, Volume 69, 1984, pages 867-876.

2Coutant, C.C., “Integrated, Multi-Sensory, Behavioural Guidance Systems for Fish Diversion,” American Fisheries Society Symposium 26, 2001, pages 105-113.

3Patrick, P. H., et al., “Responses of Fish to a Strobe Light/Air-Bubble Barrier,” Fisheries Research, Volume 3, 1985, pages 157-172.

4Patrick, P.H., J.S. Poulton, and R. Brown, “Responses of American Eels to Strobe Light and Sound and Introduction to Sound Conditioning as a Potential Fish Passage Technology,” American Fisheries Society Symposium 26, 2001, pages 1-11.

5Schilt, C.R., “Developing Fish Passage and Protection at Hydropower Dams,” Applied Animal Behaviour Science, Volume 104, 2007, pages 295-325.

6Hamel, M.J., M.L. Brown, and S.R. Chipps, “Behavioral Responses of Rainbow Trout to In Situ Strobe Lights,” North American Journal of Fisheries Management, Volume 28, 2008, pages 394-401.

7Miehls, S.M., N.S. Johnson, and P.J. Hrodey, “Test of a Nonphysical Barrier Consisting of Light, Sound, and Bubble Screen to Block Upstream Movement of Sea Lampreys in an Experimental Raceway,” North American Journal of Fisheries Management, Volume 37, 2017, pages 660—666.

8Allen, G., S. Amaral, and J. Black. “Fish Protection Technologies: The US Experience,” Chapter 17, Operational and Environmental Consequences of Large Industrial Cooling Water Intakes, Springer-Science Publications, 2012.

9Noatch, M.R., and C.D. Suski, “Non-Physical Barriers to Deter Fish Movements,” Environmental Review, Volume 20, 2012, pages 1-12.

10Rodgers, D.W., and P.H. Patrick, “Evaluation of a Hidrostal Pump Fish Return System,” North American Journal of Fisheries Management, Volume 5, No. 3A, 1985, pages 393-399.

11Sullivan, B., et al., “The Use of Different Spectra of Light Emitting Diodes for Behavioural Guidance of a Warm-Water Teleost,” North American Journal of Fisheries Management, Volume 36, No. 5, 2016, pages 1000-1005.

12Ford, M.I, et al., “Evaluating a Light‐Louver System for Behavioural Guidance of Age‐0 White Sturgeon,” River Research and Applications, Volume 33, No. 8, 2017, pages 1286-1294.

13Vowles, A.S. and P.S. Kemp., “Effects of light on the behaviour of brown trout (Salmo trutta) encountering accelerating flow: Application to downstream fish passage,” Ecological Engineering, Volume 47, 2012, pages 247-253.

14Elvidge, C.K., C.R. Reid, M.I. Ford, and Steven J. Cooke, Behavioural Guidance of Age-1+ and Age-4+ Lake Sturgeon using Coloured LED Light and Ontogeny of Blue Light Avoidance, Prepared for ATET-Tech, Thornhill, Ontario, Canada, 2018.

15Ford, M.I., et al., Preferences of Age-0 White Sturgeon for Different Colours and Strobe Rates of LED Lights May Iform Behavioural Guidance Strategies, Environmental Biology of Fishes, 2018.

16Elvidge, C.K., et al., Behavioural Guidance of Yellow-Stage American eel Anguillla rostrata with a Light-Emitting Diode (LED) Device, Endangered Species Research (in press).

Paul H. Patrick, PhD, is director of research and A.M. Sills, PhD, is director of business with ATET-Tech, Inc.