User manual

Science Manual – Using Video Images for Fisheries Monitoring 45
A1.2 Larinier pass
A) If the pass is equal to or less than 900 mm wide, one camera chamber is
required (Figure 23). The light panel can be mounted in either a bed or side
recess and a polypropylene board mounted in the other recess:
Stop log grooves
Recess for lighting/polypropylene boards
Camera channel
Baffle section
Flow
620mm
Downslope in this area
(optional, but preferable)
Figure 23: Plan view of counting arrangement on Larinier pass up to 900 mm
Side recess
See general specification (Figure ). If to be fitted on a slope, a 30 mm deep recess
running the length of the slope and extending to a height at least equivalent to Q10,
with a white polypropylene sheet cut to fit and bolted in place, is ideal.
Fixing the light panel
Light panels to be fixed down by attaching counter-sunk (at bottom edge) flanges to
the Perspex sheets. Using coach bolts with the head on the river side will mean that
no turbulence will ensue from the bolts. Some form of fixing will be needed over the
Perspex sheet slots to ensure that they cannot ride up, and this could be something
that covers the top of the camera slot. This means that the light board shape remains
standard and simple, and it is a simple approach easily fabricated.
Bed recess location
Down slope. Fish behaviour is likely to be more predictable on the down slope of a
pass than on the level with slower water. But logistically, it can be more difficult to
locate a light panel on a down slope and the dimensions can be restrictive. The
lighting panel can be an adjustable length, perhaps down to 300 mm where the head
of the pass is severely restrained.
Camera channel
Camera channel to be installed central to the bed recess and centrally opposite the
side recess (Figure 23). See general specification for details.
Camera mount
See general specification.
Stop log grooves
Stop log grooves (100 mm x 100 mm) situated on either side of the lighting to allow
isolation of lighting panels and camera chamber for work and maintenance (Figure
23).