Delta Smelt

Delta smelt (Hypomesus transpacificus) are a highly endangered small fish that eat insects and find themselves at home in Emeryville’s local salt marsh. They are able to handle a large range of salt concentration. As a keystone species, like salmon, these tiny fish are incredibly important, playing a crucial role in the food chain. Smelt are so important, their presence allows scientists to estimate the overall health of the San Francisco Bay Delta. When the delta smelt population is in decline, species that rely on smelt as a reliable food source begin to decline as well, initiating a cycle of ecosystem degradation for the entire delta. These populations used to number in the thousands, but recent trawls have only brought back less than ten of these critical species. Unfortunately, there were zero found in 2020 survey. They are suffering from greatly reduced cold water flows on dammed rivers, getting trapped in Delta conveyance water pumps as well as power plant intakes. Water contamination and competition and predation from nonnative species also play a role in the delta smelt's decline.