BY JOHN WALDMAN AND THOMAS QUINN
s two aquatic conservation biologists who have long studied riverine fishes, we know of few rivers in the Lower 48 states with migratory fish populations equal to what European colonists first encountered. Indeed, the losses have often been profound, e.g., six orders of magnitude for American shad in the Susquehanna River. We examined the challenge of restoring salmon, steelhead, shads, sturgeon, eels, lamprey and other diadromous fishes (those migrating between fresh and salt waters) through the prism of “tractability.” That is, regardless of historical causes, what meaningful restoration actions can be taken today? The many “drivers” that reduced these populations differ in how important they are and how tractable they are to resolution. T R O U T
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