Canned tuna is one of the most consumed fish in the world, with the U.S. leading the way, despite a dip in consumption in the last 25 years. But the popularity of the fish and its value in the marketplace as its price has increased has led to practices such as illegal fishing, overfishing, and fishing methods that capture and harm other species, called bycatch.

Now for the first time, Greenpeace has scrutinized and rated the practices of companies offering canned tuna—and it found most of them lacking. It found that more than 80 percent of the canned tuna sold in the U.S.comes from sources engaging in unsustainable and destructive fishing practices.

Greenpeace’s 2015 Canned Tuna Shopping Guide, available on their extremely user-friendly website, rates 14 widely available brands and ranked the three biggest—Bumblebee, Chicken of the Sea and StarKist—among the worst performers, talking about sustainability without practicing it or providing little information on their sourcing policies. It gave eight of the 14 a failing score.

“Consumers should know that popular and trusted canned tuna brands are contributing to ocean destruction at an alarming rate,” said Greenpeace seafood markets lead Graham Forbes. “While the biggest brands have thus far refused to offer sustainable tuna, the silver lining here is that other companies are stepping up to provide ocean safe options for their customers.”

The guide looked at whether the common tuna fishing practice of longline fishing, which can capture up to 35 percent bycatch such as sea birds, turtles and sharks, was used or if it involved shark finning, the practice of removing shark fins and tossing the carcass back into the sea. They looked at whether the companies even tracked their product back to the practices used to catch it. They also examined labor and human rights violations in the tuna fishing industry and whether the companies had policies in place to avoid them.

“Unfortunately, dolphin safe does not mean ocean safe,” said Forbes. “Turtles, sharks and other vulnerable ocean life are collateral damage in tuna fisheries that supply the U.S market. The big players have a responsibility to join forward-thinking brands in building a more responsible tuna industry. As the market continues to shift, selling products that are bad for our oceans will be bad for business.”