Determining the entrance position of fish in trawls
Abstract
The entrance position of a fish is defined as its two-dimensional position in a cross section of a
trawl near the centre of the headline. Individual fish entering the trawl: detected by highresolution
scanning sonar, were positioned by digitising the co-ordinates of the echo relative to
the trawl panels. Entrance probabilities for different species may be computed for grid elements
on the cross section, integrating the positional information over an entire trawl haul, and studied
as a function of light level, density and fish size. Examples of entrance probabilities for cod and
saithe on a few selected trawl hauls are shown.
Publisher
ICESSeries
ICES CM documents1999/J:13