The salmon who pay our light bill
one. Every year, young Chinook salmon run the Sacramento–San Joaquin Delta on their way to the sea. A working landscape glows: the corridor the fish cross is a corridor of our light. The light doesn't chase them. It introduces them to things with teeth.
two. A NOAA and UC Santa Cruz team asked a population-level question: not what light does to one fish, but what removing it does for a whole migration. Their model turned off every artificial light source in the Delta. Conservative result: up to 1,123 more salmon, per million that try, would make it through.
three. About one fish in a thousand. Salmon repair usually pays in dams, wetlands, years of water fights. This fix's price is darkness. The paper's note: cost and contention here are trivial next to other restoration projects. On a menu of expensive fixes, this one costs almost nothing.
four. One asterisk: a model, conservative, “up to”. But a price that runs toward free. The fish get no vote and no thank-you. The strange, cheap help waiting for them: lights off over the water, after dark. Up the river, a million small travelers are coming. Lehman, Burford and colleagues, Biology Letters 22:20260304, 2026. PMID 42710882.
Sources: Lehman et al., Biology Letters (2026). doi:10.1098/rsbl.2026.0304 · PubMed 42710882
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