Mercury in Fish

[big walleye]

What causes a high mercury level in fish? Are there some fish that have higher mercury levels? How much can one consume before it effects you? What are the symptoms of poisoning? I just have heard of it over the years but never bothered to ask the question. I would appreciate it if anyone can supply some information.

[billditrite]

that is a big problem in many states,including here in maine,your states fish and wildlife should give you information and consumption guidelines
 http:// www.maine.gov/dhs/ehu/fish/

[Esox]

Fossel fuels (coal is the biggie) are the main problem. After they are burned the mecury that has gone into the air comes back in rain form into the rivers and streams. Smaller species have less merury. Larger fish that eat the smaller fish take in that mecury and have higher levels. Mercury does not leave the fish until it's dead, so the older/larger the fish the greater the potential it has for hight mercury levels. Yet another reason to keep smaller fish to eat.

 

[Bigfish57]

don't forget that bottom dwelling fish have also been found to have higher levels too.

[billditrite]

yes ,naturally heavy metals sink to the bottom,cold water species are more succeptible...i dont eat them anyway...not anymore

[Esox]

I believe the whole bottom dwelling theory is a myth. I'll confirm tomorrow, but all the information I have read shows it is directly related to the diet of the fish that is in question. The highly preditory fish have a higher Hg level. Maybe Cider can shed some light on this?

Here is a link on Hg levels in different fish. Notice shellfish, haddock, cod, flounder, pollok, hake, etc is some of the lowest, thus going against the bottom dwelling fish theory.

http://www.maine.gov/dhs/ehu/fish/hgposter.shtml

[billditrite]

you may be right i really have no idea...i do see what you are saying ,i notice the much higher levels in the fresh water fish but not neccessarily the coldwater species

[big walleye]

Hey guy's keep the information coming. Thanks for taking the time.

[Scott]

Check out this site.

http://www.epa.gov/mercury/


-Scott

[Esox]

Thanks Scott.

There is some info from that site...

Q: Do some fish contain more mercury than others?

A:  Yes. Predator fish – big fish that eat smaller fish – tend to have higher methylmercury concentrations than other fish. The Food and Drug Administration has issued advise to pregnant women regarding consumption of certain types of fish. States issue fish advisories that inform consumers of the extent to which they need to limit their consumption of locally caught fish. Certain species of commercially available saltwater fish, such as shark and swordfish, kingfish and tilefish also can contain high levels of mercury.


Q: What adverse effects on human health are related to mercury?

A: Methylmercury is highly toxic to mammals, including people, and causes a number of adverse effects. Health studies and information showing neurotoxicity, particularly in developing organisms, are most abundant. The brain is the most sensitive organ for which suitable data are available to quantify a dose-response relationship. A recent study by the National Academy of Science concluded that the population at highest risk is the children of women who consume large amounts of fish and seafood during pregnancy, and that the risk to that population is likely to be sufficient to result in an increase in the number of children who have to struggle to keep up in school and who might require remedial classes or special education.

[Cider]

I believe the whole bottom dwelling theory is a myth. I'll confirm tomorrow, but all the information I have read shows it is directly related to the diet of the fish that is in question. The highly preditory fish have a higher Hg level. Maybe Cider can shed some light on this?

I've been following this thread but haven't commented because the information is all pretty good and I didn't feel the need to duplicate what was already said.

Bob - you are correct.  Bottom dwelling doesn't have anything to do with mercury levels.  The predatory nature of the fish and its appetite will dictate how much mercury is in it.  The size and age of the fish are also contributing factors.

Mercury cannot be digested or excreted by the body.  Therefore, it bioaccumulates and the levels of mercury keep rising with more and more acid rain and the more fish are predating on each other. The bigger and older the fish, the more it has eaten and the longer it has been around to ingest mercury.

Bob is right, stick with the smaller fish for table fare.  They will have far less mercury and as a general rule are tastier and easier to cook.  Although...usually for lakers, the bigger the fish the better it is.  A 15 lb laker tastes much better than a 5 lb laker!

Just don't eat more than one meal a month of fish if you are female and plan on having kids.  Don't be fooled into thinking that stocked fish should be free from mercury and therefore you can eat more.  Most stockies are raised in raceways that are exposed to the same elements that natives are.  Stockies might have slightly lower levels of mercury, but you should still stick to the same consumption rules.

Just check your local wildlife authorities for consumption guidelines.  Some waters are off-limits altogether!  Depends on if they are associated with pulp mills and the textile industry etc.

[Mackdaddy21]

We have one lake in Colorado with this problem. Sanchez reservoir in Southeastern Colorado is in an old coal mining region. It has one of Colorado's best pike fisheries and a good walleye population, along with jumbo perch and Channel Catfish. Signs along the lake strongly urge anglers not to eat walleyes or pike over a couple pounds due to mercury accumulation in larger fish. I am sure most of this happened, as Bob said, from all the Coal mining and burning that used to go in this region. Mercury poisoning is not something to mess around with. It can cause permanent severe neurological defects. When hat makers used to use mercury to treat their pelts, they would inhale the vapor, and slowly over time develop nervous ticks, and other brain damage that would dub them "mad hatters." Many of them died on down the road from a lethal accumulation of mercury.

Tyler

[Esox]

Bob - you are correct. 

I better write that on the calender......It does not happen very often.

[Cider]

If you cut and paste wisely, you can make it happen as often as you wish!!! 

[Esox]

If you cut and paste wisely, you can make it happen as often as you wish!!! 

Not if you ask my wife.....I'm always wrong, even when I'm right.