River Teifi Hydroacoustic Fish Counter Annual Summary - 2005
Once again I'm very grateful for this information which Mr. Richard Davies from the Fisheries Assessment Team in the Environment Agency Wales has compiled for the club. The DIDSON equipment which Richard refers to is an interesting piece of kit which you can learn about here. Put simply, it's a bit like the ultrasound scans that the health service use to look at unborn children in the womb.
Introduction
This report presents results from the River Teifi hydroacoustic counter for 2005, the seventh year of full operational deployment. It follows previous work done to estimate the counter efficiency (the proportion of fish detected by the counter) from underwater camera recordings of fish movement at the site.
Fish Counts
The total provisional validated count for 2005 was 11,383 fish, with the majority of fish migrating from June to August (see Table 1). The counter was operational for 90.3% of the year with a total downtime of 853.5 hours.
Table 1: Monthly breakdown of provisional counts from the Glanteifi counter for 2005
Month |
Fish per hour |
Validated count |
Jan |
0.03 |
43 |
Feb |
0.02 |
23 |
Mar |
0.05 |
71 |
Apr |
0.22 |
262 |
May |
0.53 |
860 |
Jun |
2.12 |
2651 |
Jul |
1.43 |
1,927 |
Aug |
1.07 |
1,525 |
Sep |
0.61 |
816 |
Oct |
0.71 |
1,090 |
Nov |
0.63 |
813 |
Dec |
1.02 |
1303 |
Total |
|
11,383 |
The 2004 and 2005 counts are lower than in previous years, but they have yet to be finalised and may change when the results of a new validation programme, undertaken during 2005, become available (see Figure 1).
Figure 1: Historical annual estimates of the total number of fish migrating past the counter (validated count).
Future Work