Oxygen & Fishing
Water oxygen levels is a vital component to the location
of holding fish and understanding what stresses may or may not contribute to
the willingness of biting fish.
Timothy Kusherets
Truly turbid conditions stain water making it nearly impossible
to see more than a few inches at a time, increases water temperature, and depletes
oxygen levels. In the photo above note how the river has deposited particulate
silt, suspended load, to either bank and that the river is running clear at
the same time. Eventually this river level will rise suspending the silt starting
the entire process all over again. Understanding natural stresses that fish
undergo makes it that much easier to put them on the bite at the first stages
of rivers leveling-out or receding.
Oxygen levels is a vital component to the location of holding fish. Areas
devoid of plentiful oxygen will have fewer fish. Determining the relative amount
of oxygen can be done by ascertaining turbidity, suspended loads, bed loads,
river depth, current speed, and foliage above and below the surface along both
banks.
Depth of river and lake water usually means that oxygen is present, provided
there is enough water movement to introduce oxygen into the environment. Shallow
water usually means that there is a depletion of oxygen that keeps larger species
of fish from gravitating to those holds. Shallow water usually means that a
lack of current is present thus making it hard for fish to survive in them.
Shallow holds can produce large amounts of air for fish provided there is a
certain amount of speed such as riffles found below a tail-out. Aside from fast
water, shallow holds are worth avoiding for fishing purposes.
Current determines temperature, oxygen, and speed of each hold. Current is largely
due to the gradient of rivers and streams. Dense riparians can keep water from
evaporating or seeping into the surrounding ground, which adds to the rate of
water flow that anglers refer to as current. Speeds of current vary by depth,
with fastest currents flowing near the surface. Holds with significant depth
often times have fish holding beneath fast water making it vital that anglers
use enough weight to get beneath fast water without using so much weight that
it startles fish at the bed of the river.
Foliage accumulation has an adverse affect on the amount of oxygen, temperature,
and speed that water flows at. The more foliage that is in a river or stream
can slow down enough that plants can literally suck the life out of the water
it’s in. Areas of water that have large accumulations of plant life in
rivers usually means that there has not been a significant amount of rainfall
for an extended period of time; this creates a unique kind of pressure that
can put fish off the bite as they struggle to breathe in the harsh environment.
Salmon, Steelhead, Trout, and Bass can all experience this type of pressure
at any given time of the year that excessive growth occurs. Ironically, there
are some systems that produce large numbers of fish that can be “seen”
during migration making them prime spots for anglers to fish; however, due to
the stress of struggling for oxygen fish don’t often bite during these
times.
Spotting excessive foliage is fairly easy when waters run clear. Waters that
experience turbid conditions due to flooding, or freshets, don’t have
sign of foliage since essential scouring rids the bed of them.
© Timothy Kusherets 2008 Copyrighted
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