After a wildfire roared through northern New Mexico this summer, state and federal biologists rescued scores of Rio Grande cutthroat trout from a small stream. They were trucked south to Las Cruces and kept in tanks at New Mexico State University for three months and recently released into another mountain creek. Wildlife agencies in the southwestern U.S. consider missions like this essential as climate change brings more frequent and hotter wildfires, fueled by prolonged drought and tree-killing bug infestations. Wildfires are followed by torrential rains that wash ashy muck into streams, killing fish and smothering their feeding and spawning areas. Fish in some places evolved to benefit from fire, which can provide nutrients and improve habitat. But giant, intense fires are causing fish kills.