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Toxic Algae Makes Huge Schools of Fish Go Belly up

Updated: Sep 08, 2022 21:40
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Toxic Algae Blooms in Oakland – photo from Oaklandside

Shocking numbers of dead fish are showing up on shores across The Bay Area as toxic algae grow seemingly out of control. The blooms have grown not just across the entire bay but, this week, folks have seen shocking numbers of dead fish popping up in smaller bodies of water like in Oakland’s Lake Merritt. 

Ian Wren, a scientist with San Francisco Baykeeper told ABC7 News, “About three weeks ago, the last week of July, we started getting reports of a very unusual brown discoloration of the water. Soon thereafter we learned the Department of Public Health had taken samples around Jack London Square and they identified the species that’s causing this bloom.” Since it was first found, the blooms have grown out of control and have been found all across the bay from 20 miles north of SF as well as near San Mateo and Fremont.

Aerial view of the toxic algae blooms – photo from the SFBayKeeper website

This type of algae is called “Heterosigma akashiwo”. It’s a marine alga that every so often for, toxic algal bloom on the surface of water. Looking at the photo above, it’s pretty clear that whatever is in the water is not what you would typically think of when you think of algae. Look for brown, mucky, sometimes with rainbow oil slick around or on top of it. It will also likely have a very nasty smell. These are all indicators that the algae in the water is toxic.

Senior scientist Jon Rosenfield told Reuters that the scope of this amount of algae in The Bay is unprecedented. He noted that we’re liking seeing this happening now due to treated wastewater containing nitrogen and phosphorous dumped into the bay by about 40 wastewater treatment centers. (Gross.) So basically, waste water combined with heat is creating perfect toxic algae conditions that are contributing to low oxygen levels likely killing fish.

Dead Fish at Lake Merritt – photo by Vita Hewitt

The algae, understandably, is also making the water look look dirty and brown. Not exactly an enticing sight to see when you’re thinking fo taking a dip in the bay. Never the less, Scientists are warning folks not to swim in the water until the algae has subsided. Baykeeper executive director Sejal Choksi-Chugh issued the following statement, “Baykeeper cautions against people or pets contacting the brown murky water, or eating fish, and particularly shellfish, caught in the area, until the algal bloom dissipates.”

Risks include potential skin irritation and burning eyes. Even if you feel like you need to take a soak and don’t care about the potential hazards, make sure to keep your pooch outta the water as it could cause more dangerous effects to animals.

A dead sturgeon sits on the shore of the San Francisco Bay at Keller Beach on Aug. 29, 2022, in Richmond, Calif. 

A beached sturgeon found in Richmond, CA – photo by Justin Sullivan/Getty Images

Anything you can do, other than staying clear of the toxic algae?

SFBayKeeper is asking us, “While this particular algae may not pose an acute risk to people, once a bloom starts to die off, it may deplete oxygen and harm to fish and wildlife, especially in shallower areas of the Bay. We’re asking the public to contact us via our pollution hotline or SFEI’s observation form if you notice a large quantity of dead fish near shoreline areas where blooms have occurred.”

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Katy Atchison

Katy Atchison

Katy has lived in The Bay Area since the age of 3. While other kids were attending summer camp & soccer practice, she was raised selling wares at craft shows with her working artist parents and spent vacations in a small 1920s Montana log cabin. This has all given her a unique perspective on the ever-changing texture of San Francisco and the Greater Bay Area. Currently a blend of all that is The Bay Area - she's a web designer at a tech-company, artist and DIY teacher.