The United States is one of the world's largest consumers of seafood, and is the largest market for canned tuna. Unfortunately, advocates have found that most tuna found on supermarket shelves comes from fishing methods that cause environmental destruction and put workers at risk.

Oceans are being depleted by overfishing and destructive fishing practices that disrupt marine ecosystems and harm wildlife. What's more, the fishing industry also relies heavily on forced labor and human trafficking, with reports of 20-hour work days, lack of potable water and nutritious food, violence and even death. In fact, a report from Pew Charitable Trusts found that 100,000 fishing-related deaths occur annually. Workers have reported being beaten, abused and forced to work on ships for months or years at a time.

Shining a spotlight on the companies profiting the most from tuna fishing, Greenpeace USA's third edition of the "High Cost of Cheap Tuna Retailer Report" scorecard measures which major grocery chains are leaders in sustainable and ethical seafood and which are falling behind. Only two of the 16 retailers surveyed, Aldi and Hy Vee, received a passing score. To find out if your supermarket is selling sustainable seafood, visit www.greenpeace.org.

The report found that while a handful of retailers have taken key steps towards improved transparency – in some cases, publishing their vessel list and vessel supplier lists so that trade unions and worker rights organizations know which companies are in the end-buyer's supply chain – others have seemed to turn a blind eye to the problem and have made only marginal improvements or have maintained the status quo.

"There should be no place for modern slavery and environmental destruction on U.S. store shelves. Retailers need to take responsibility for the products they are selling and profiting from," said Charli Fritzner, Greenpeace USA's Beyond Seafood project lead.

According to Fritzner, consumers can make an impact by starting a dialogue with their grocery stores. She advises asking about their tuna suppliers, including whether the store can trace their tuna back to the vessel it was caught on, what they know about the people working on the vessels and their rights, and what policies their suppliers have in place to minimize bycatch of other animals, such as sharks or marine birds.

So how can you make sure the food you feed your family isn't harming people and the planet?

"Individuals can use their voice to let big retailers know that sustainable, ethical seafood is important to them," Fritzner said. "However, the onus rests on the retailers themselves. They can build trust with their shoppers and communities by knowing where the food stocked on their shelves comes from, including the labor involved and environmental impact in producing it."