Simrad ES70 Operator's Manual page 85

The biomass is automatically calculated based on choices you make in the
Calculation Interval
a portion of the echogram view. The data is then taken from an echo area starting
immediately after the transmit pulse, and ending just over the detected depth. If
you have limited your vertical range (using the
the resulting area is used for the biomass calculation. If the seabed is clearly
defined with a unique bottom detection, the bottom echo will not be included in the
calculations. Therefore, if you switch the bottom detector off, the bottom echo will
be included in the calculation.
→ Biomass information pane on page 59
b
Bottom
The echogram is related to the detected bottom. Stop depth (lower echogram
boundary) and vertical range are manually selected by the
buttons on the
Main
successful bottom detection.
The biomass calculation is made in the same way as for
c
Pelagic
This echogram is nearly identical to the
calculated in a different manner.
The biomass calculations are not restricted by the bottom detection. This means that
the bottom echo will be included in calculations if it appears within the chosen range.
Example 9 Biomass calculation
If you are investigating a large school of pelagic fish, set the
and
Range
echogram may mistake it for bottom, and the biomass readings will
be wrong. The
detection, and give a correct estimate of the biomass.
d
Trawl
This echogram covers the vertical opening of the trawl.
The echogram is only drawn when trawl position information is available.
The biomass calculation is made in the same way as for
This procedure explains how to choose the echogram type you wish to see.
Click the
1
Active
→ Active menu on page 107
2 Click
Echogram
343539/B
dialog; within a given time frame, a defined number of pings, or
menu. The echogram is only drawn for pings having a
to enclose the school. If the school is large enough, a
echogram will however disregard the bottom
Pelagic
icon under the menu to open the
Main
to open the
Echogram
Operational procedures
and
Range Start Range
Start Depth
Surface
echogram. However, the biomass is
Surface
Surface
Active
dialog.
settings),
and
Range
echograms.
Start Range
Surface
echograms.
menu.
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