The Bottom Contact Sensor attaches to the combination wire just
behind the footgear. An inclinometer is used to provide the angle
of the sensor. Essentially, when the trawl is on bottom, the
sensor is horizontal and provides an angle of about 90°. When the
trawl comes off bottom, the sensor is oriented vertical and
displays an angle of approximately 0°.
A number of sensors have already been delivered to the US and Europe
with excellent results reported. The trawl can come off bottom for
various reasons. For example, not enough trawl wire is used.
Another cause could be fishing too fast into currents which can
lift the trawl off bottom. Regardless of the reason, when a bottom
trawl comes off bottom, fishing is greatly reduced.
This is an essential tool when pelagic trawling in that it can
greatly reduce tear-ups by indicating if the trawl has touched
bottom.
This Bottom Contact Sensor is also important for scientific
studies as bottom contact information is essential for swept area
calculations.
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