Underwater Visibility and Fly Selection
For years, divers have known about a phenomenon called "deep
water color shift". This phenomenon could use a better name, because
the appearance of certain colors underwater can shift in a depth of as little as
three feet. Understanding this phenomenon and how it affects the
visibility of your offering can have a dramatic effect on your catch rate.
A fly that isn't easily seen is one that's easy for a fish to ignore, and
a fly that's easy to ignore is one that stands little chance of being eaten.
Essentially, water acts like a light filter. Certain wavelengths of light
are filtered, depending on whether the water is fresh or salt, and how much and
what types of suspended material it contains.
The inshore waters that most of us fish, of course, are salt waters. Because
salt water contains more suspended inorganic material in it, and less suspended
organic material in it, than fresh water does, the general rule is that light in
the blue-green spectrum is often the most visible in the shallow underwater
environment.
A good rule of thumb is: fish green water with a green fly, and blue water with
a blue fly. White is a good, visible color, regardless of whether marine
water appears blue or green from the surface, and it makes a good contrasting
color when used with green or blue. Chartreuse, as most of us know from
experience, is a good, visible color in the waters that most of us fish, and it
is one of the colors that is visible from the longest distances.
Contrast is also an important element in getting a fish's attention. This
is achieved in green over white and chartreuse over white Clouser Minnows, to
good effect. Dark spots on a light background ad additional contrasting elements
that make a fly very difficult for a fish to ignore. The proof of this is
born out by the effectiveness of rainbow trout colored Rapala CD crankbaits that
some gear fishers troll in Newport and San Diego Bays. The lure works
because fish can see it well from a considerable distance.
It so happens that most of the game fish that we in Southern California seek to
catch when fishing inshore salt water have eyes that are tuned to see blue and
green especially well.
I can sum this all up by stating that you will get more takers when fishing
Southern California inshore salt water areas if you chose flies based on the
ability of fish to see them, rather than their ability to exactly replicate
natural forage. Fish flies that are chartreuse or green, contrasted with
white and the addition of dark spots, and you will know, with a certain
conviction, that your fly will be seen by the fish that you seek to catch.
-Jerrold