Partial Migration of Fishes as Exemplified by the Estuarine-Dependent White Perch

Abstract

Abstract Partial migration defines the phenomenon of coexisting groups exhibiting migratory and resident behavior within the same population. In avian ecology, partial migration is a fundamental behavior that underlies the evolution of migration in general. Among fish taxa, the terminology and theory associated with partial migration has predominantly been used to describe salmon ecophenotypes, but the behavior is more widespread. Here, we ecophenotypes, but the behavior is more widespread. Here, we document partial migration for the estuarine-dependent white perch (Morone americana), in the Patuxent River estuary (Chesapeake Bay, Maryland), wherein a portion of the population resides in freshwater natal habitats and another portion migrates down-estuary into brackish water (salinities>3) habitats. Life-time migration histories were examined using otolith strontium:calcium profile analysis. Alternative life history tactics, initiated during the juvenile period in response to individual physiological condition, persisted over the lifetime of the individual and had population-level consequences, including differences in growth rate and productivity. Based upon a review of recent literature, we argue that pratical migration is more widespread among fishes than previously recognized, and such population structure has important implications for population dynamics and persistence.