Well thankfully fish coming from Oregon rivers tend to be far lower in Mercury than your typical can of Charlie the Tuna. The government under Obama is currently on a mission to destroy the coal industry. The CO2 scare is not quite cutting it anymore... so they have moved on to another contaminant that they feel will be more effective. By setting acceptable mercury emissions at levels in the parts per billion range which cannot possibly be complied with they feel they can finally get rid of coal once and for all.
“The only cases in the scientific literature of mercury poisoning from eating fish on record were from fish tainted after an industrial chemical accident in Minamata Bay, Japan in the 1950s, which resulted in fish with methylmercury levels 40 to 1,000 times higher than the fish Americans, and most people around the world, eat.”
http://junkfoodscience.blogspot.com/2008/12/do-fish-fly.html