March 30, 2011

Massive Fish Die-Off in Redondo’s King Harbor, Southern California


By Reef Check California’s SoCal Volunteer Coordinator Laurel Fink
Photos courtesy of RCCA volunteer Dana Murray

Millions of sardines were found belly-up in the north side of King Harbor the morning of March 8, 2011. This massive amount of dead fish (>140 tons) has caused a huge clean-up effort and quite a smelly mess for the slip owners and residents around the harbor.

Initially believed to be a cause of solely oxygen deprivation in the narrow enclosed areas of the harbor, results from samples of fish tissues showed a high amount of domoic acid present in the sardine’s stomachs. This neurotoxin, which is released during phytoplankton blooms, reached high levels in Santa Monica Bay about 12 miles offshore of the harbor in the days prior to the fish die-off. Authorities from the University of Southern California and California Department of Fish and Game think now that the domoic acid caused the sardines to become disoriented and swim into the harbor, and caused increased physiological stress brought on by the low oxygen levels in the water. With millions of sardines enclosed in the small harbor space, the remaining oxygen in the water was quickly used up by the huge demand of so many fish. Additionally, the storms in the southern California area prior to this event may have caused waves to further push the schooling fish into the harbor. King Harbor experienced a similar fish die-off about 5 years ago, also caused by a red tide bloom event in the bay.

King Harbor is located right at the mouth of Redondo Canyon, which is a highly productive area bringing cold, nutrient rich water to the surface, ideal conditions to cause phytoplankton blooms, especially when coupled with additional nutrient input such as that from urban runoff. A week later, the cleanup was still underway, involving sucking up the dead fish that have settled to the bottom of the harbor in a 2-foot thick layer. Cleanup from this die-off will cost the City of Redondo Beach more than $100,000. 

On a positive endnote, the removed tonnage of sardines are being transported to Victorville (American Organic) to be reused and composted into organic fertilizer.