Southeast Asia is on the verge of completely killing off its once-bountiful turtle populations to feed the voracious demand for the critters in China, where they are sought as food and medicinals. Biologists say that in Cambodia, Laos, Thailand, and Vietnam, it can be nearly impossible to find even a single turtle in national parks and remote areas. Researchers have resorted to looking for turtles, even very rare species, in Chinese markets and restaurants, and they say some species are being sold into extinction before scientists can even identify them. Exports of U.S. turtles are now rising, and some worry the U.S. populations can’t sustain the higher harvests.