Anadromy and homing: two life-history traits with adaptive synergies in salmonid fishes?

Anadromy and homing are two traits found widely amongst teleost fishes. They co-occur in salmonid fishes, and probably also in other fish families. Anadromy provides fish with the opportunity for more rapid growth, larger size, and higher fecundity through the exploitation of rich food resources and favourable growing temperatures in the sea, but may result in higher predation mortalities and has the tendency to disperse stocks very widely. Homing fosters adaptation of stocks to favourable local spawning conditions, but the dispersive effects of anadromy, in the absence of homing, may tend to break down such local adaptation. A low percentage of straying in species that home may have long-term evolutionary advantages. This paper explores the question of whether homing may be a preadaptation for successful evolution of anadromy, or whether the two attributes have coevolved.