Tuna, Pacific Bluefin – Troll (Kuro maguro) 
Pacific Bluefin Tuna are commonly caught by troll fishing, which has very low levels of bycatch and causes no habitat damage. They are typically found in the North Pacific, and can travel huge distances from their spawning grounds in the western Pacific to the eastern Pacific.
Pacific Bluefin Tuna are fished for by many countries including Japan, U.S., and Mexico, and they are prized on the sashimi market. Due to high demand and market value, fishing pressure is too high and Pacific Bluefin Tuna are uncommon.
This fish may have high levels of mercury that could pose a health risk to adults and children. More mercury info here.