Tuna, salmon and other things are finding themselves pinned to the sea floor from eating so much mercury, in much the same way a teenager can’t get out of bed from being laden with the torments of society misunderstanding him.
Sea creatures acquire a portfolio of heavy metals through the other sea creatures that they eat, which did the same thing – making the heavy metal economy a giant pyramid scheme: except it’s the guys at the top who are lumbered with all the useless crap. The higher up the food chain you go, the higher percentage of metal they are, increasing their density until they sink straight to the sea floor. The fish survive because their prey will always be floating slightly above them, by virtue of their slightly lower metal content.
The effect on the fishing industry has been largely positive. Fishermen have reported higher catches of heavier tuna now that the dolphins can’t get to them, though this increased revenue is offset somewhat by the cost of providing a sachet of chelating agent with each can. The metallic sheen also makes the fish look fresher, boosting sales; though this is no indicator of actual freshness as it takes years for microbes to get a foothold in meat and spoil it, given the mercury content.