One of the nation's largest supermarket chains has claimed the top spot in the Greenpeace seafood sustainability report, released Tuesday. Safeway, which operates more than 1,700 stores under various names, including Vons, was praised for discontinuing sales of "red-list," or unsustainably caught, species, including orange roughy.

"Safeway broke new ground with this new report," said Casson Trenor, senior markets campaigner for Greenpeace.

Safeway's move into first place from its fourth-place ranking last year was due in part to the company's involvement in fishery improvement projects to rebuild fish stocks. Most significant, it's made a public statement calling on the governments that control fisheries in the Antarctic Ross Sea to designate it as a marine reserve.

The environmental activist group used four criteria to determine seafood retailer rankings in its fifth Carting Away the Oceans report: seafood purchasing policy, participation in political or conservation initiatives, transparency about what is being sold at the point of sale and how many types of red-list fish a retailer sells.

About half of all seafood is sold by seafood retailers; the rest is purchased at restaurants, Trenor said. Three years ago, all 20 of the seafood retailers Greenpeace assessed failed the organization's seafood sustainability test. This year, 15 received a passing score, though none attained the Greenpeace criteria for truly green retail.

Target and Wegman's shared the No. 2 spot on the report, with Whole Foods ranking fourth and Costco, Trader Joe's and Walmart ranking 11th, 12th and 13th, respectively. SuperValu, which operates Albertson's stores, ranked 18th and did not receive a passing grade.