Juvenile salmonids transit through marine waters to access non-natal habitats for rearing

Anadromous salmon species and populations display diverse life history patterns that collectively confer resilience. However, substantial habitat degradation has likely impacted the opportunity for life history expression which may have contributed to recent population declines. Among the myriad management actions underway, protecting and restoring juvenile rearing habitat has been identified as critical to salmon recovery. Much of that effort has focused on juvenile rearing habitat within natal watersheds (i.e., the watersheds where salmon spawn and emerge). However, observations over the past two decades have revealed that juvenile salmon will also rear in non-natal habitats, and specifically habitats that require access by moving through marine waters. This behavior, which we term “habitat shifting through the marine environment” (HSME), is largely absent from dominant conservation discussions for salmon populations. Here, we review the evidence for HSME across salmon species, habitats, and geographies, discuss potential mechanisms, and pose future research questions related to HSME and the potential role in restoration and recovery planning using Puget Sound as a case study.