Book excerpt: Readers who believe as Herman Melville's Ishmael, that "meditation and water are wedded for ever," will be entranced by Rex Johnson, Jr.'s, account of his travels to the upper Bavispe River in Mexico's northern Sierra Madre. Combining travel observations, natural history, ethnography, ecology, and ichthyology, Johnson's narrative plunges the reader into a world that is so far from the twenty-first-century United States that it is difficult to believe how physically close the two countries actually are. Johnson goes in search of an ancient species of trout, the Bavispe, at least 3 million years old. It has been easier for the Bavispe to remain unchanged for millennia than for the human inhabitants of the Sierra Madre to endure for mere centuries. Johnson notes the area's Indian descendants are in the process of becoming modern, and the needs of the ancient trout, dependent on pure, unpolluted water, collide at times with the choices of people scratching out an existence in a challenging environment. The parallel stories from natural and human history are a central theme in Johnson's account of environmental change and its consequences, layered with the personal, contemplative meaning he finds in the quest for the seldom-seen fish.