Why should salmon care about the weather? A paper by Ann Gargett, 1999 previously of Dept. of Fisheries and Oceans, British Columbia, Canada now at Old Dominion University, Center for Coastal and Physical Oceanography, Virginia Available online at

First several months of life are in coastal regions so timing of food resources there is important. Are there enough zooplankton to eat while salmonids are growing to adults phase?

Ocean stratification and nutricline are affected by both large and small scale physical processes (e.g., Ekman transport, up/downwelling, mixing). Plankton must “go with the flow” and cannot fix themselves into a single “best” spot as do land plants.

Ekman transport sets general nature of nutricline in both gyres, but with opposite effects (i.e., sub-polar is enhanced, sub-tropical is depressed). Sub-tropical gyres have more light on average, but subpolar gets it longer light in summer (recall sharp peak in primary production). Actual transport of nutrients is also determined by small-scale turbulence which is a strong function of stratification.

Out-of-phase mechanism now available IF 1)there is a linear connection up food web from phytoplankton to salmon and 2) strength of Aleutian low directly affects coastal stratification and therefore nutrient supply to phytoplankton.

Note that higher stability prevents turbulent mixing, and lower stability enhances it.

Note that in north stability is driven by salinity (precip), and in south by upwelling (winds).