I've frequently suggested that fibre optics would be useful to daylight culverts in instances where it's impractical to open them up immediately. People are using this method to bring natural light into their living rooms, why not into culverts. Is there something that prevents this method, I've been suggesting it for years. For instance, there are thousands of yards of creekbed that are inaccessible to salmon in Pacific Spirit Park because of the length of the culverts crossing Marine Dr. and yet this method has never been employed.
I think cost is probably an issue. Also, I think daylighting fish habitat is not just about light, but also about food sources and fresh air accessing the water surface. If I'm not mistaken, the fish ideally require some riparian habitat to provide thriving insect/invertebrate life, and also benefit from fresh air in contact with water surface to disperse toxins/maintain oxygen levels.