Simrad ES80 Reference Manual page 242

Simrad ES80 Reference Manual
acoustic energy scattered by a group of targets is the sum of the energy scattered by
each individual target. This assumption holds well in most cases. The total acoustic
energy backscattered by the school or aggregation is integrated together, and this
total is divided by the (previously determined) backscattering coefficient of a single
animal, giving an estimate of the total number.
http://en.wikipedia.org/wiki/Fisheries_acoustics, March 2015
The ES80 records all the targets from the smallest plankton to the largest whale. The
biomass value is an indicator to how much fish you currently have in the beam. Every
single fish will emit an echo, and the sum of all these registered echoes are presented as
a number. Smaller organisms such as plankton will also emit echoes, but these are so
weak that they will hardly influence on the total biomass.
The biomass value provides you with information about the fish abundance, and as such
it may help you to decide if it pays off to start fishing. However, you must consider if the
biomass value is a result of large amounts of plankton or bait, or if you have "real fish"
below the keel. The biomass value is relative, and after some use your experience will be
a valuable factor when the decision is made.
Note
You may experience very high and unrealistic biomass values that do not match the
information in the echogram.
If you have other echo sounders or sonars running asynchronous with the ES80, these
systems may cause interference. The ES80 may detect and measure the transmit pulses
from other hydroacoustic systems, and these pulses have an effect on the biomass
calculations.
Try the
Ping-Ping Filter
previous consecutive pings in order to remove unwanted noise and interference from the
ES80 presentation.
To avoid all interference, a full synchronization of the various acoustic instruments is
required. If your own vessel produces excessive noise this will also be taken into the
biomass calculations and give you inaccurate data.
It is possible to convert the biomass index to weight (for example in metric tons). Based
on practical use of the ES80 in different fisheries, you will soon be able to estimate the
weight when you know the type of fish and their sizes.
Tip
The Biomass Line allows you to monitor the current biomass in the echogram. This
function writes an extra thick and brightly coloured curve on the echogram. The
Biomass Line shows you the measured biomass for each individual ping. You can change
the scale of the curve to fit the vertical space available on the echogram. To enable the
Biomass Line function and change the scale, use the
box.
240
. The
Ping-Ping Filter
analyses the historical information from
page in the
Lines
dialog
Echogram
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