Why should salmon care about the weather?

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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
• http//oceanworld.tamu.edu/students/fisheries/salm
  on_weather/Annsdoc.html

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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?
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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.
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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.
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• Out-of-phase mechanism now available IF
• 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.

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Note that higher stability prevents turbulent
mixing, and lower stability enhances it.
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Note that in north stability is driven by
salinity (precip), and in south by upwelling
(winds).
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