MPCA Finds Mercury Levels In MN Walleye, Pike Rising Since 1990s After Initial Decline

[hatrack]

An analysis of a 25-year record of mercury in northern pike and walleye from Minnesota lakes has found an unexpected rise in mercury concentrations in these predator fish. The Minnesota Pollution Control Agency (MPCA) study was reported in the peer-reviewed journal, "Environmental Science & Technology," on Feb. 9.

"In the decade before the mid-1990s, the methylmercury concentrations in northern pike and walleye from the great majority of Minnesota lakes were decreasing," said MPCA scientist Bruce Monson, who conducted the analysis. "However, the analysis showed that the fish-mercury concentration in the majority of lakes has been increasing since the mid-1990s."

The analysis was based on tissue contaminant measurements obtained from fish collected from 845 Minnesota lakes. The finding is of concern because methylmercury, the form of mercury that contaminates fish, is toxic to humans and wildlife. Some of the mercury that is deposited from the air is converted to methylmercury by bacteria that live in the sediments of wetlands and lakes. Methylmercury accumulates in the aquatic food chain, with predator fish, such as pike, having the highest concentrations.

Because the trend is statewide, a local source of mercury is likely not responsible for the increase. Monson said the most likely cause is either increased global mercury emissions by sources outside the United States or factors associated with climate change, or both. Global mercury emissions increased between 1990 and 1995, due in large part to the increased production of electricity by coal-fired power plants in Asia, particularly in China and India. One effect of climate change is greater fluctuations in water levels, which results in more mercury being converted to methylmercury and being available for accumulation in the aquatic food web.

EDIT

http://www.shakopeenews.com/news/general_news/mpca_unexpected_rise_sport_fish_mercury_levels-102

[MineralMan]

1. That's why I'm catch-and-release almost

exclusively. I do eat my catch once in a while, but not often, and I never eat large, old fish. They have accumulated more mercury during their lives.

Oddly enough, it's safer to eat fish like carp, which are primarily vegetarian. Their flesh accumulates far less mercury that predator species.

[DCKit]

2. The predators and, especially, the bottom feeders are most toxic.

I searched around the web one night last year and found that there are consumption warnings and bans on almost every stream, river and lake in the country.

Thanks George!!!

[Enthusiast]

3. I've eaten enough large

Northern Pike that I should be a thermometer by now. Seriously, the was we threw away this wonderful resource is enough to make you sick. The Ohio River and tributaries are now teeming with walleye and sauger, all deemed unsafe for human consumption.

[Viking12]

4. The risk is to developing neurosystems, women who are or plan to be pregnant and young children

Fully developed adults are at far less risk of effects from methyl-mercury.

[Enthusiast]

6. Yes, I am aware of this. thanks nt

[Viking12]

5. Wait for teh antiv-axxers to jump on this....

"see, see, see...there are health warnings about mercury1!!11!!!1! and it's in vaccines!!!!!111!!1"

[kristopher]

7. Gee, I wonder if this is related...

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x187365