But there also seem to be other factors in play. Although yellowfin tuna is very lean, this species tends to have lower accumulation of mercury, likely because yellowfin are typically smaller than other tuna and are harvested at a younger age. Furthermore, yellowfin are tropical and do not thermoregulate like the warm-blooded bigeye tuna and bluefin tuna. Because bigeye and bluefin species eat three times more than yellowfin to maintain their energy level, they might bioaccumulate, or slowly increase the level of toxins over time.
"Although levels are highest in top-level predatory fish, some fish that are lower on the food chain have high levels," says Joanna Burger, professor at Rutgers University. "The levels of mercury in some tuna are sufficiently high to provide a health risk both to the fish themselves and to the predators that eat them, including humans, particularly those who eat fish frequently."
"We show how you can use DNA as a tool to uncover patterns of species-specific bioaccumulation," says Sergios-Orestis Kolokotronis, a geneticist at the Sackler Institute for Comparative Genomics at the Museum. "This is one of first applications of DNA barcodes in a non-academic settingusing this method in any human health context and not just for determining whether barcodes can quickly and accurately identify a species."
|Contact: Kristin Elise Phillips|
American Museum of Natural History