Serena Fitka sat in the cabin of a flat-bottomed aluminum boat as it sped down the Yukon River in western Alaska, recalling how the river once ran thick with salmon. Each summer, in the Yup’ik village of St. Mary’s where Fitka grew up, she and her family fished for days on end. They’d catch enough salmon to last through winter, enough to share with cousins, aunts, uncles, and elders who couldn’t fish for themselves.