The Founding Fish

John McPhee's twenty-sixth book is a braid of personal history, natural history, and American history, in descending order of volume. Each spring, American shad-Alosa sapidissima-leave the ocean in hundreds of thousands and run heroic distances upriver to spawn. McPhee--a shad fisherman himself--recounts the shad's cameo role in the lives of George Washington and Henry David Thoreau. He fishes with and visits the laboratories of famous ichthyologists; he takes instruction in the making of shad d