Biomass information pane description
The Biomass information pane displays an index of the biomass in the in the current Inspection view. The biomass index is the sA value, or Nautical area scattering coefficient (NASC), measured with unit m2/nmi2.
How to open
Before you open an information pane, you must first click in an Inspection view to make it "active". The information provided will only be valid for the selected view.
To open the Biomass information pane, click in the chosen view to activate it, then select the Biomass button on the top bar. To close the information pane, select it one more time on the top bar. You can also select Close in the top right corner of the pane.
Information panes are only available for Inspection views.
Description
The digit shown in the Biomass information pane is a calculated index.
If more than one target is located in the acoustic beam at the same depth, it is not usually possible to resolve them separately. This is often the case with schooling fish or aggregations of zooplankton. In these cases, echo integration is used to estimate biomass. Echo integration assumes that the total 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 ST90 system 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.
If you have other echo sounders or sonars running asynchronous with the ST90 system, these other systems may cause interference. The ST90 system may detect and measure the transmit pulses from other hydroacoustic systems, and these pulses have an effect on the biomass calculations. 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.
You can easily change the physical size and shape of each information pane. Click in its lower right corner, and drag to a new size. To reset the information pane to its default size, select the Reset size button in its top right corner.
The Transparency function allows you to adjust how much you are able to see "through" the information panes you have opened. You can adjust the setting from 0% (no transparency) to 90% (almost full transparency) in steps of 10%.
