Rockfish Mercury Levels - Humboldt BayKeeper

Interesting stuff, glad that they study it.

Guidelines -
https://www.humboldtbaykeeper.org/images/PDF/EatingFish2-English.pdf

Article -
https://www.humboldtbaykeeper.org/mercury-assessment/1472-mercury-study-extended-to-coastal-fish

Full Report -
https://www.humboldtbaykeeper.org/images/PDF/BaykeeperMercuryPhase2FinalReport.pdf

Definitely interesting and not always intuitive. Looks like a 7 lb ling will likely have a higher mercury concentration than a 40 lb pac hali.

Thanks for posting this.  I target fish with low mercury levels so this is a great resource.

Be aware it varies by location.

https://oehha.ca.gov/advisories/statewide-advisory-eating-fish-california-coastal-locations-without-site-specific-advice

https://oehha.ca.gov/fish/ca-fishmap

https://oehha.ca.gov/advisories/san-francisco-bay

It's kind of depressing...

https://oehha.ca.gov/advisories/statewide-advisory-eating-fish-california-coastal-locations-without-site-specific-advice

Interesting things to me from that link:

Halibut not listed?

Rockfish have varying mercury levels by species, I have seen them all lumped in other sources.

Lingcod are "safer" than many rockfish species despite being rockfish predators.  This doesn't make a ton of sense to my understanding of bioaccumulation, but I'm guessing the people who study this for a living know more than some dude who got a marine bio degree 20 years ago...

what the hell happens to the poor perch down there?! maybe runoff from storms or something. I fished ferry pier during a rain event and it smelt like a pool petroleum...

You mean on the SF Bay Chart?  Man, I have no idea, but the bay is really it's own world when it comes to legacy industrial and military pollution.  The perch in the bay must eat something (some kind of invert?) that has really been soaking up something nasty from the bottom.  There are also watersheds in the south bay that have naturally occurring high mercury levels, though I'm not sure whether that is concentrated enough to matter once the bay dilutes it.

Luckily the perch on the general coastal waters charts are fine, especially the barred that are most common and the best table fare perch in my neck of the woods.

Lotta the mercury in the bay is from gold mining/processing. Lots of deposition from Sac and SJ River tribs draining out of gold country. Also a bunch of Bay Area mercury mines (South Bay especially). Fish that prey on the bugs that live in the mud (where the heavy metals settle) are bound to be higher. Predatory fish that target midwater bait fish should have lower concentrations.

Rockfish feed a lot on brittle starfish which are surface gleaners and could be ingesting deposited mercury. Midwater rockfish like blacks and blues might have lower levels doing less feeding in the deposition zone.

Lings will eat anything including midwater baits, so it seems like it could be more of a roll of the dice with them.

I am pretty sure if you search mercury levels safe to eat fish you will find some scientific articles indicating that  even   fish ( not whales or seals) that have high mercury levels are not causing mercury poisioning because of the  Selenium in fish or the person who eats it makes mercury    not harmful to the person who ate it. Just follow the science! I always assumed if eating fish was so bad for you that we would see hundreds or thousands of people being diagnosed with mercury poisioning. I am more concerned about all the chemo drugs that cancer patients pee and pooh into our waste treatment plants and they are not treating for that at all that flows into our ecosystems.

Hrrrm, that is interesting about selenium, I hadn't read about it before.

This (https://pubmed.ncbi.nlm.nih.gov/29124976/) literature review from 2017 indicates that the interaction of selenium and mercury isn't exactly that selenium protects against mercury.  Rather, it's that mercury does (at least some of) it's damage by inhibiting selenium uptake, and thus selenium supplementation (presumably including high selenium levels alongside mercury in the fish you eat) somewhat solves the problem by making more available.  At least if I'm reading it right.

Conclusion from the abstract:

Conclusions: The interaction with selenium is a central feature in mercury toxicity. This interaction is complex depending on a number of features such as the form of mercury, the form of selenium, the organ and dose. The previously suggested "protective effect" of selenium against mercury toxicity may in fact be backwards. The effect of mercury is to produce a selenium deficiency state and a direct inhibition of selenium's role in controlling the intracellular redox environment in organisms. Selenium supplementation, with limitations, may have a beneficial role in restoring adequate selenium status from the deficiency state and mitigating the toxicity of mercury.

Anyway, that's just one article, there is I'm sure a ton more to read and a million additional PhD projects to do on it, but definitely an interesting twist for me in the fish and mercury question.  Biology and chemistry are complicated.

Kind of apropos of nothing, it's interesting that the watersheds of the south east bay (Almaden hills specifically) have a ton of naturally occurring mercury, and the hills of the south west bay (Permanente creek specifically) have a ton of naturally occurring selenium.  Both of these areas have watersheds that are impaired by their signature minerals due to mining (historic and current, respectively).

So I wonder if south bay fish contain a supercharged speedball of selenium and mercury that counteract each other?  Someone needs to do a PhD project on that one.

I take a selenium supplement occasionally, not sure why, read about its benefits somewhere.

Shiners are loaded with Mercury as are leopard sharks.  Perch eat plenty of shrimp and there are pile worms in the bay as well...

I always assumed if eating fish was so bad for you that we would see hundreds or thousands of people being diagnosed with mercury poisioning.

There’s a few of us on this board that have tested high for mercury and used chelation and lower fish/shellfish consumption to lower mercury levels.   Was it fish?  Was it dental fillings?  Something else?  Who knows.

Eat low on the food chain, and don’t eat fish at all out of places like clear lake. 

I always assumed if eating fish was so bad for you that we would see hundreds or thousands of people being diagnosed with mercury poisioning.

I mean I would suspect that half the people on this board are crazy, have you heard of mad hatters disease? I myself have an insatiable thirst to catch fish. I will probably one day become a crazy old fisherman singing/drinking Brandy out loud in an alleyway lol.

Hey Brandaay, you're a fine (you're a fine girl)
What a good wife you would be (such a fine girl)
But my life, my lover, my ladaayyy is the SEA (doo doo dood ood ododoodoo)

Keith Fraser at Loch Lomand is aging well and he's eatin' his share I suspect.

I mean I would suspect that half the people on this board are crazy

I take offense to this... It is WAY more than half.