June 4, 2018
The interaction between light pollution and predation could deal a heavy blow to species already struggling to survive. Bridges, in particular, often have lighting that shines into rivers at night, and attraction to these stationary lights can stop juvenile fish in their tracks as they migrate downstream, making them vulnerable to predators. Fish also frequently migrate and feed at night to hide from predators in the darkness, and bright lights shining on the water eliminate their protective cover. In rivers where salmon spawn, juvenile salmon can be especially impacted by bright nighttime lights or reflections on the surface of the water because predation is a major contributing factor to the high mortality of juvenile salmon. Light pollution from the iconic Sundial Bridge in Redding, California (shown above), was a suspected factor that contributed to the near loss of Sacramento River fall-run Chinook salmon from 2011–2013.