Giant Otters and Mercury

Today Giant Otters are threatened by Mercury spills in their freshwater rivers. This is one of the reasons these otters are endangered today. While these spills don't directly kill them it shortens their lifespans. With these reasons more Giant Otters are dying then getting born. If Giant Otters had a Mercury resistant layer in their fur it would make the Giant Otter's amount of Mercury go down. However most of the Mercury comes from their diet, if Otters had a filter in their stomach then they would get rid of 90% of their Mercury.