yellowfin tuna

They found that mercury concentrations in yellowfin tuna increased about 5.5 percent per year between 1998 and 2008.

Levels in bigeye tuna increased about 3.9 percent per year from 2002 to 2008. Mercury concentrations tended to be greater in bigeye tuna than in yellowfin tuna.
 
The work was reported in a study scheduled for online publication March 6 in the journal Environmental Toxicology and Chemistry.

The changes, it explained, are in line with the resolutions of the Inter-American Tropical Tuna Commission (IATTC), of which Mexico is a party.

This measure also applies to boats from the Mexican flagged purse seine fleet fishing for these species in the high seas and in foreign jurisdictional waters that are in the IATTC regulated area.