User manual

4 Science Manual – Using Video Images for Fisheries Monitoring
2.2.4 Equipment housing
At some sites, you may be lucky enough to have a gauging station hut or similar in
which to store recording hardware. On other sites there may be no sheltered storage
and you will have to install your own cabinet or hut (for supplier information, see
Section 3.1). Bear in mind the location of the site and the likelihood of vandalism, as
this will affect the material you choose and where you decide to locate the housing.
2.3 River characteristics
Rivers vary widely in flow characteristics and turbidity, which affect the quality of the
images you obtain and will influence how you design the video counting system. For
example, a camera looking sideways with a light panel fixed to the opposite side of
the fish pass will work better in turbid conditions than a camera looking over a light
panel on the bed of the pass. However, the latter system will provide you with more
information in the image to help with speciation.
Other site-specific features to watch out for are whether the area acts as a debris
trap for all of the flotsam coming down the river, or whether the water is very
turbulent. In both cases it is advisable to find another site or, if possible, to address
the problem, for example by using debris booms or by removing the cause of the
turbulence.
2.4 Cost
Video monitoring systems are the cheapest tools available for counting fish in passes
and channels, but systems can range in price depending on the components
selected. Costs increase as the width of the pass increases, mainly due to the cost
of lighting the area. Infrared lamps or illuminators are a slightly cheaper, though less
even method of illuminating the counting site than light panels; however, image
quality may not be as good and may not work as well with the image processing
tools.
The approximate cost bands in the selection matrix (Table 2.1) do not include
provision for installing a mains power supply or a method of continually charging
batteries on site.
2.5 Incorporating video counting into a fish pass
2.5.1 New passes
Appendix 1 provides the design specifications for the head of a fish pass. The
features detailed in this can be included at the design stage of fish pass construction
and the costs, which are a mere fraction of the total build costs, budgeted for at an
early stage.
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