Temperature is very
bad, when the water is warm the fish can not breath. Also if the water gets
to warm there is a thing called PDO which stands
for Pacific Decadal Oscillation. PDO is a result
that the shift it causes in the sea surface temperature.
The surface temperature of the water
stand's for PDO
is by water that is cold water in the Northern Pacific and there is a strip
of warm water. The warm water has an effect on the salmon populations. PDO
can last up to 20-30 year. PDO has not yet been
identify.