We hear about periodic alarming levels of domoic acid in our seafood. Levels are monitored constantly and closely by our California Department of Fish & Wildlife (DFW), and when levels rise above health thresholds, they issue warnings about eating certain types of seafood.
One common (pretty much annual) warning is to not eat bivalve shellfish such as mussels, scallops and clams. The DFW issues warnings, continues monitoring and lifts warnings when levels drop.
The old school rule before the DFW did such good testing was to not eat bivalve shellfish in months ending in R. That old generality didn’t always work well for us, and I thank the DFW for doing such good work now.
Domoic acid also affects finfish. A warning was recently lifted regarding Pacific sardines. Human consumption was unwise and perhaps dangerous, so the commercial fishery was curtailed except for catching them to be used for bait, south of Point Conception.
Now they are safe again for people to eat and the fishery is back in business.
When finfish build up high levels of domoic acid, it affects the upline food chain and we see strange and sad things happen. Examples include, marine mammal strandings and birds losing their ability to navigate safely (think of the old Alfred Hitchcock movie “The Birds”).
Those are some of the results of domoic acid. Explaining the origins is kinda tricky because it starts out exceptionally low in the natural oceanic food chain (way down at the single-cell level) and works its way up and concentrates as it goes.
Were I to explain it in my own words, I’d probably turn it into a story line, because I’m a natural story-teller. So instead, I’ll relate the origin explanation from the DFW.
“Domoic acid is a potent neurotoxin produced by Psuedo-nitzchia, a naturally occurring single-cell marine alga, under certain ocean conditions. Domoic acid can accumulate in fish without the organism itself becoming ill. At low levels, domoic acid exposure can cause persistent short-term memory loss, seizures and can in some cases be fatal.”
We know it is naturally occurring and isn’t a newish issue, so this isn’t one of those things where people who want to close off the ocean blame us and want to keep us off of and out of the water.
Yet it certainly can affect us, so the ongoing system of monitoring and warning and temporarily shutting down affected fisheries is a good way to manage the impacts on humans.
What I find sad is how it impacts other ocean critters. It does explain the seemingly unexplainable strandings of marine mammals and the occasional erratic and uncontrolled actions of seabirds.
