Homing and Straying in Pacific Salmon

Abstract

The remarkable ability of Pacific salmon (genus Oncorhynchus) to home to their natal stream to spawn has tended to obscure the fact that a small proportion of the spawners stray to non-natal streams. it is hypothesized that straying is an evolutionary alternative to homing and that theses two life-history strategies are in dynamic equilibrium. Straying should be relatively common in populations spawning in unstable streams (high annual variation in juvenile survival), and in species and populations spawning in geographically simple streams with similar nearby streams. Straying should also be relatively common in species with little variation in age at maturity.