WASHINGTON — September 13, 2015 — Federal lawmakers, State Department officials, fishing and pet food companies, and class-action lawyers are stepping up efforts to combat forced labor at sea.

Last week, a group of consumers filed a class-action lawsuit in California against Mars, accusing the company, among the biggest producers of seafood-based pet food in the world, of failing to disclose its dependence on forced labor. A similar lawsuit was filed in late August against Nestlé, also a major producer of seafood-based pet food.

Several lawmakers have also begun trying to address the problem. Senator Richard Blumenthal, Democrat of Connecticut, proposed legislation in August aimed at increasing transparency and accountability in corporate supply chains. The bill requires larger companies to report in their financial filings what they are doing to prevent the use of trafficked workers.

Representative Carolyn B. Maloney, Democrat of New York, who introduced similar legislation in the House,  sent a letter last week to the National Oceanic and Atmospheric Administration, or NOAA, which monitors the oceans, urging the agency to focus not just on illegal fishing but also on preventing “trafficking and slavery in the fishing industry.”