Fish can detox too -- but not so well, when it comes to mercury. By examining the tissues at a subcellular level, researchers discovered yelloweye rockfish were able to immobilize several potentially toxic elements within their liver tissues (Cadmium, lead, and arsenic) thus preventing them from interacting with sensitive parts of the cell. But mercury was found in concentrations known to be toxic - and most of it was in sensitive sites, such as mitochondria and enzymes, within liver cells. Source 3g.
Alaska is very stringent about protecting it's wildlife. It’s unfortunate that these contaminants drift in outside of their control because someone else does not care.