A federal appeals court yesterday rejected the U.S. government’s bid to loosen the standard for “dolphin-safe” tuna. The U.S. wanted to open its dolphin-safe market to Mexican and Latin American fishers who catch tuna in large purse-seines and promise to set free dolphins trapped in the nets. But the 9th U.S. Circuit Court of Appeals upheld a lower court ruling, preventing the U.S. Commerce Department from moving forward with the new standard until it conducts more studies on whether dolphin populations would be hurt by the change. The issue has split the environmental community. The Earth Island Institute, which filed the suit, said the new standard would lead to more dolphin deaths. But World Wildlife Fund and others argued that the standard would create economic incentives for foreign governments to make sure tuna fishing doesn’t harm dolphins.