Large–scale Ocean and Atmospheric Indicators

Local and Regional Physical Indicators

Local Biological Indicators

Indicators Under Development

Introduction to Pacific Northwest Oceanography

Ocean Sampling Methods

Salmon Predation Index

A salmon predation index will integrate four variables found to influence predation rates of Columbia River salmon in the ocean (Emmett 2006).  These variables are based on the following spring (May/June) measurements: 

Abundance of Pacific whiting (hake) off the Columbia River Abundance of forage fish off the Columbia River Turbidity of the Columbia River Columbia River flows

Predator and forage–fish abundances are estimated annually from the Predator/Forage Fish Survey, and turbidity will be estimated using satellite imagery, Secchi disc readings, and transmissometer measurements, each of which has been collected since 1998.  Initial analyses indicates that during years when hake abundance is low and forage fish abundance, turbidity, and Columbia River flows are high, salmon marine survival is high.  However, if even one variable has an opposite value, salmon marine survival declines.