Dead Fish Line the Shores at Lake Merritt

From the ecological calamity at Lake Merritt in Oakland this morning … images of the huge fish die-off, likely related to the algal bloom on SF Bay. The cause hasn’t been confirmed, although the algae is at the top of the suspects list.

According to naturalist Damon Tighe who reported on the situation at the lake on Sunday, measurements of the water showed the lake to be anoxic — so depleted of oxygen, the numbers were less than one part per million. You can see an interview with Tighe in the video below, where he discusses his observations in more detail.

Dead fish at Lake Merritt

Walking the shore from the Lake Chalet to the Rotary Nature Center, we couldn’t fully count the number of dead and dying fish, rays, and other aquatic animals that lined the lake’s shore. It seemed endless. Tighe counted 39+ dead bat rays and 522+ dead striped bass. That doesn’t include the thousands of smaller fish and animals we saw lying at the lake’s edge, dead or dying in the muds of the receding tide.

Dead Bat Ray in Lake Merritt
Dead Bat Ray in Lake Merritt
Fish Kill in Lake Merrit

Bearing witness to these events can feel inconsolable at times. The scene today was utterly heart crushing.

Fish Die-Off and Algae Bloom in Lake Merritt

Algae Bloom on San Francisco Bay

According to a piece in the SF Chronicle today, this is the largest algal bloom we’ve seen in the region, “dominated by a harmful species known as Heterosigma akashiwo.”

From the same article, Ian Wren, a scientist with San Francisco Baykeeper says:

“We’ve never seen this before and even the models that have been developed didn’t see this as being possible.”

Algal blooms are expected to increase with climate change and warming waters.

Dead Fish at Lake Merritt
Fish Die-Off in Lake Merritt

Among the dead fish were those still living which, in turn, drew a frenzy of pelicans, egrets, and cormorants to feed.

Fish Die-Off on Lake Merritt
Snowy Egrets Reflected at Lake Merritt
Snowy Egret Fishing on Lake Merritt
Brown Pelican Fishing at Lake Merritt
Double-crested Cormorant Fishing in Lake Merritt

I hope the presence of active, live fish speaks to increased oxygen levels for the coming days, although that would be an optimistic vision. I don’t know how this bloom and its cascading effects will impact the birds, short term or long. Our fall and winter bird migrants will soon descend on these marshes and shores for their winter sustenance, and no one can say yet how significant the disruption will be to the Bay Area’s food chain. I hope it will be far less than what I fear.

❤️ to Lake Merritt and our beautiful SF Bay

Interview with biologist Damon Tighe, about the fish die-off, the algal bloom, and his observations at Lake Merritt

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