28 SEPTEMBER 2015 • WORLD AQUACULTURE • WWW.WAS.ORG provide a variety of different light color outputs. Figure 3 indicates the spectral output of four LED lamps for aquaculture at 100 percent intensity. The light spectra of each lamp would be perceived as white light but each lamp would have enhanced intensity in a certain span of wavelengths (color) for a certain stage and/or species of fish that produces a favorable response in feeding activity. It is also possible to coordinate use of a LED light with particular wavelength specifications with dimming possibilities so that the lighting system can change with the changing needs of fish larvae. Figure 3 also indicates the spectral change of lamps when dimming occurs. Summary The production of high numbers of robust fish larvae and subsequent healthy juveniles represent a significant bottleneck in many marine fish hatcheries. The first-feeding period of all fish larvae, in nature and controlled culture conditions, is a critical time. Either larvae are able to identify and aptly respond to food sources in their environment by successfully capturing and ingesting enough to remain nutritionally fit or fail to consume sufficient amounts of food and subsequently die of starvation. Furthermore, pelagic larvae rely on vision to capture prey and use photoreception as a means of determining their position in the water column. In hatcheries, finding the correct environmental lighting for marine fish larvae is complex, but is an important consideration because survival of 30 percent is not uncommon in larval fish culture. Larvae respond to light in their environment and all three characteristics of artificial environmental light (intensity, photoperiod and wavelength) contribute to successful larval rearing. Furthermore, the required timing and modulation of light intensity and wavelength spectra during larval stages varies with species. New developments in artificial lighting using LED technology are providing hatchery managers with a broader range of control than offered by traditional lighting sources. These new technologies allow more precise manipulation and measurement of light intensity and spectrum from a single lighting system and enable aquaculturists to isolate, remove or enhance the effects that these parameters may have on larval performance. Consequently LED technology provides an opportunity to enhance larval fish production. Notes Dr. Juliette Delabbio is Director of Research and Development for ONCE Innovations Inc., a lighting company specializing in LED lighting for aquaculture. Her contact email is jdelabbio@ onceinnovations.com. References Barahona-Fernandes, M. 1979. Some effects of light intensity and photoperiod on the sea bass larvae (Dicentrarchus labrax (L.)) reared at the Centre Oceanologique de Bretagne. Aquaculture 17:311-321. Batty, R. 1987. Effect of light intensity on activity and foodsearching of larval herring, Clupea harengus: a laboratory study. Marine Biology 94:323-327. Berg, O.K. and V. Moen. 1999. Inter- and intrapopulation variation in temperature sum requirements at hatching in Norwegian Atlantic salmon. Journal of Fish Biology 54: 636-647. Blaxter, J.H.S. 1986. Development of sense organs and behaviour of teleost larvae with special reference to feeding and predator avoidance. Annual Larval Fish Conference 115:98-114. Blaxter, J.H.S. 1975. The eyes of larval fish. Vision in Fish. Ed. M. Ali, NATO Advanced Study Institutes Series 1:427-443. Blaxter, J.H.S. 1968. Light intensity, vision, and feeding in young plaice. Journal of Experimental Marine Biology and Ecology 2:293-307. Blaxter, J.H.S. 1966. The effects of light intensity on the feeding ecology of herring. Pages 393-409 In: R. Bainbridge, G.C. Evans, and O. Rackham, editors. Light as an Ecological Factor. Blackwell, Oxford, England. Blaxter, J.H.S. and M. Staines. 1970. Pure-cone retinae and retinomotor responses in larval teleosts. Journal of the Marine Biological Association of the UK 50:449-460. FIGURE 3. First row shows the spectral output at 100 percent intensity of four LED lamps (ONCE innovations Inc). The second row shows the spectral output of the same lamps when dimmed to the light intensity levels indicated. MLA-WH 120V MLA-RE 120V MLA-BL 120V MLA-GY 230V MLA-WH 120V AT 5% MLA-RE 120V AT 50% MLA-BL 120V AT 50% MLA-GY 230V AT 40%
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