To sea or not to sea: A brief review on salmon migration evolution

Abstract

Since many salmonid species have the alternative life history strategies, they provide us a good opportunity to solve such a riddle. In a model, the anadromous life history of salmon may not be an evolutionarily stable state. If the gain in fitness from staying in a river exceeds the fitness from the sea, the fluvial life history can occur or vice versa. Some data may support these predictions. The relative reproductive success of migratory and fluvial females has latitudinal variation (so called geocline); the latter will be higher at the southern limits of the ranges, and conversely, the former will have higher fitness at the northern part, probably supporting the food availability hypothesis. © 2002, The Japanese Society of Fisheries Science. All rights reserved.