US Army Corps of Engineers
Portland District Website Website

Process overview: refuge

Landscape-scale interactions of juvenile salmonids with estuarine habitatsRefuge provides protection from predation or energy demanding aspects of the ecosystem. Refuge can reduce losses from predation, energy loss due to swimming (i.e., against currents), and other physiological stresses due to exposure.


The figure at bottom left shows the use of large woody debris and channel habitat by juvenile salmon in the estuary (Simenstad 2001).


The figure at bottom right shows that salmon performance within the estuary is directly linked to population structure upriver, habitat opportunity, and habitat capacity. Hatchery releases, salmon harvest, and watershed modifications alter population structure and also may affect patterns of salmon rearing and migration in the estuary (Bottom et al. 2001).



Diagram of refuge process

Structures that affect refuge:

  • Scrub-shrub forest
  • Emergent marsh
  • Submerged aquatic vegetation 


Ecosystem functions that are affected by refuge:

  • Aesthetics / recreation
  • Biodiversity maintenance
  • Salmonid production
  • Other fish production
  • Avifauna production
  • Wildlife production

Contact information

Ronald Thom, Ph.D

Marine Research Operations, PNNL
1529 W. Sequim Bay Rd.
Sequim, WA 98382