There's uncertainty about the health and abundance of blue marlin populations; however, Seafood Watch recommends blue marlin from Hawaii as a "Good Alternative", due to minimal bycatch by the U.S. fleet.
When purchasing blue marlin, be sure that it was caught in the Hawaiian fishery.
Environmental Defense Fund has issued a health advisory for blue marlin due to high levels of mercury.
Blue marlin is an open ocean species found throughout much of the world's temperate and tropical oceans. Limited and uncertain information on the blue marlin population in the Pacific makes assessment difficult.
The blue found in Hawaiian markets are mostly accidental bycatch in the tuna longline fisheries. There is considerable concern about bycatch from longlining. However, fishery managers and fishermen in the U.S. fleet have made great strides in reducing bycatch in recent years through changes in regulations and modifications to fishing gear.
While blue marlin caught by the Hawaiian fleet is still recommended as a "Good Alternative," consumers should note that illegally caught marlin from the Atlantic Ocean is available on the U.S. market and is ranked as "Avoid."