What’s happening to all the dead fish around SF Bay amid the algal bloom?

Clean-up operations began Wednesday at Lake Merritt to remove thousands of fish killed in the midst of a harmful algal bloom which is spreading in San Francisco Bay and adjacent waters.

Contractors hired by the Oakland Department of Public Works were knee-deep in lake mud, using nets to scoop up fish carcasses littering the shore and placing them in trash cans. The cleanup began early Wednesday morning and is expected to last all day and may even continue Thursday, Oakland Public Works spokesman Sean Maher said.

“It’s hard work. It’s never a bad day to thank a frontline worker,” Maher said.

Maher said the fish will be placed in biodegradable bags, transported in trucks and then incinerated, in accordance with national regulations for this type of material. Crews hope to complete the cleanup before this weekend Heat wave brings abnormally high temperatures to the region.

“We are carrying out this work today with the aim of reducing a public nuisance. The smell is really something else – we want to make sure the lake is comfortable to visit,” said Maher.

Cleanup crews began on areas of the lake with the highest concentrations of dead fish and wildlife, such as at the intersection of East 18th Street and Lakeshore Avenue. Once workers clear these hot spots, they will sweep the entire circumference of the lake.

The crews collect the fish in nets and place them in nearby bins.

The crews collect the fish in nets and place them in nearby bins.

Sam Moore, SFGATE

The Oakland Department of Public Works has been working with the California Department of Fish and Wildlife and the San Francisco Bay Area Water Quality Monitoring Board since May to trace contaminant levels and blooms of harmful algae throughout the region.

“The magnitude of what we are experiencing today is greater than it has been at any time recently,” Maher said. “People are recognizing that this is a huge regional phenomenon, and Lake Merritt is certainly a place where we are experiencing it acutely. But we are part of a bigger whole here.

Eileen White, executive director of the San Francisco Bay Area Water Quality Monitoring Board, said her team was monitoring water quality at the lake and throughout the bay to determine what caused the take off of this algal bloom and what conditions were necessary for it to reach this magnitude.

She suspects that the decomposing algae and phytoplankton caused the lake’s oxygen levels to drop at an alarming rate, and that’s what killed the fish, not the algae itself.

“Phytoplankton decomposition, algal bloom decomposition, consumes oxygen necessary for fish survival in a healthy ecosystem and can lead to fish kills. I think that’s what we observed,” White said.

The Oakland Department of Public Works hopes its cleanup efforts will allow the lake to once again be a pleasant gathering space ahead of the long weekend. In the meantime, Maher said, the city is advising people to avoid touching water or anything that might float in it.

“In particular, it is very important to keep children and pets, especially pets, away from these materials. The contaminants we see have stronger impacts on them than they do on adult humans,” Maher said.

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