1. How much would it cost to put a counter on our river?
Below is a quick guide price of what the counter equipment might cost without any CCTV, modems etc., these are supplied by several different companies so the final cost might differ.

1.1 Resistivity: circa 10,000 Euro; very reliable and accurate BUT specifications for weir are strict
1.2 Infra-red: c. 18,000 Euro; easy to install BUT fish must be guided into a narrow count zone (c. 45x60 cm)
1.3 Hydroacoustic: c. 60,000 Euro; easy to install BUT requires strong degree of technical expertise
1.4 Acoustic Imaging: c.75,000 Euro; easy to install & interpret BUT relatively new technology

The cost of a counter is greatly influenced by whether civil engineering works are required to modify flow regimes / guide fish to a "count zone". Under the majority of situations, an existing weir or fish pass is modified to accommodate a counter. If no suitable structure is available, a purpose built weir is normally constructed. On larger rivers, however, construction costs may be too high so an acoustic counter might be an option BUT the river profile must meet very specific criteria for an acoustic system to operate well.

2. Where can I view the latest counts on-line?
Counts for the Marine Institutes counters, up to the end of 2002, can be viewed from the following link: http://www.fishcounter.com/mi_counters/.

The information from the counter had been downloaded and posted on the web by us as a part of a contract during 2002 with the Marine Institute. This contract was completed at the end of 2002 and as a result we are not presently in a position to report more recent figures.

3. How well do counters work?
Broadly there are two factors that ultimately determine the quality of the data collected by any counter installation.
3.1 Site design and infra-structure. These are critical to the performance of a counter. If the site is inappropriate to the equipment being used or if units are exposed to damage the performance of a counter will be drastically reduced.
3.2 Equipment reliability. Considering that counter installation are sited in relatively harsh environments subjected to winter floods, debris and general wear and tear, counters, if well maintained can perform exceptionally well.

4. Do you really need to use CCTV?
Ultimately the goal of operating a fish counters is to achieve the highest levels of performance and reliability regardless of counter type. Ideally the goal would be that 100% of all fish movements are counted, however, under varying environmental conditions a level of error must realistically be expected. CCTV validation of counter sites allows the operator the opportunity to assess, reduce and monitor this level of error. With any counter types each record of a fish movement does not implicitly indicate fish passage. In addition to this, it is as important to demonstrate to what extent, if any, fish passing through the counting zone are being underestimated (missed). Once the error level of fish counter performance is known, the total counts for the river can be readjusted. Indeed, in addition to improved data quality and monitoring error levels, video evidence can be one of the strongest tools available to demonstrate to the general public the effectiveness of fish counters and fish passes.
See CCTV page for more background.

5. Will woody debris be counted as a fish?
Most types of counter available do make attempts to discriminate fish passage from non-fish "events", the success of these can be variable depending on the technology used and site specific situations. These are usually determined by firmware within the counter but post-processing of data can also be applied.

6. What IS a pseudograph trace?!?
A pseudograph trace is an output generated by a resistivity counter used to illustrate the passage of a fish over a set of electrodes. Typically a fish will generate a sine wave the amplitude and length of this wave will be proportional to the size of the fish, its proximity to the electrodes and the swim speed of the fish. If the counter detects debris passing across the electrodes the graph trace will be typically more erratic.

7. What’s all the noise at the beginning of my graph?
This is a copy of the text file used to generate the graph:

S 19/03/02 01:05:22 214 1 E 100
D A@@@@OOOO@@OO@A@A@@@B@B@A@AOO@A@COO@B@@OOOO@@@@
D @B@B@A@BOO@AOO@B@A@AOLOBNFMGLEJLHGHAHAHAHAHKKINE@L
D CDECFDFLFNG@G@FJFHFBEKDOCLALOALEIDHDHHIEKAMDNMOK@C
D @B@B@@@C@B@A@B@B@A@A@C@C@C@C@D@A@B@A@B@C@C@C@A@A
F 1

The computer has incompletely logged the text file. The computer, defaulting to a power saving mode, may cause this. When new data arrives at the comm port, the computer takes a few moments to start up the hard drive again, some of the transmitted characters may be 'lost' during this time.
Click here for further details (adobe acrobat reader required).