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Rev 20201007
READING FISH
Fish will generally appear as separate targets from the bottom.
Depending on the size of the fish and the location within the transmit
beam they can show as any of the colors in the palette you are
using. RED indicates the strongest signal on all the color palettes,
and this generally indicates a fish directly below the transducer.
Smaller fish or fish on the outside of the cone may appear orange,
yellow, or even green or blue. Fish moving through the transmit
beam may change color as the return signal strengthens or
weakens reflecting their location.
Some fish, like walleyes, are notorious for cruising right on the
bottom. The MarCum MX-7GPS has target separation fine enough
that it will generally show bottom hugging fish as a separate signal.
However, fish that are right on the bottom can appear as part of the
bottom. The best indication of a fish sitting right on the bottom is that
the leading edge of the bottom return signal is a thin band of a color
other than red, possibly dithering or flickering. It is important that the
sensitivity be kept to a minimum when displaying a strong bottom
return. Having your sensitivity too high will flood out the ability to
differentiate targets and clutter the display.
Utilizing the ZOOM feature can give you a magnified look at the
bottom when this is happening, and help you better learn what is
going on below you.
Schooling fish, like panfish, will sometimes group in large numbers
suspended off the bottom. A big school of fish concentrated in one
portion of the water column can show on your sonar as one large
“blob”, and it can be difficult to pick out individual targets. Zooming
in on the zone with the most fish will give you better definition and
switching to the 8-degree cone will eliminate signals from fish on the
periphery of your area, improving your definition even more.