New York Times: Countering their expectations, biologists working in Bangladesh have found a thriving population of 6,000 Irrawaddy dolphins, a species restricted to brackish bays and rivers from southern Asia to northern Australia that marine mammal experts had worried was vulnerable to extinction. The population, many times larger than any other known regional groups of the dolphins, was revealed in 2004 in the first systematic survey for marine mammals along Bangladesh’s coast of waterways, bays …