Golden Algae Threatens Fish

A small number of carp, catfish and mosquito fish are currently thriving in Lago Santa Margarita along with an abundance of turtles, crawdads and birds. However, Golden Algae is still a very real threat to fish, not only Lago Santa Margarita but to the neighboring Lakes in and around Southern California.

Golden alga (Prymnesium parvum) is a single-celled organism that lives in water. It occurs worldwide, primarily in coastal waters, but it is also found in rivers and lakes. It doesn't always cause problems, but when it "blooms," (enters a phase of rapid growth and reproduction) this algae can produce toxins that cause fish kills. The toxins affect organisms that have gills: all types of fish, freshwater mussels and clams, and the gill-breathing juvenile stage of frogs and other amphibians.

A golden algae fish kill may last for days, weeks, or months. Sometimes only a portion of a lake is affected, but the location can change from one day to the next. Blooms are more likely to occur in cold weather, and sometimes taper off as the water warms and other species of algae become more active — but not always. An extended kill can have long-term effects on a fishery and cause economic hardship for parks and businesses that serve recreational anglers.

SAMLARC has been battling Golden Algae for more than two years with the last fish kill occurring in November 2015. Since that time, various treatments have been tried with no long-term