Laxräknare  Torneälven – Pajala
Lohenlaskenta –
Tornioväylä  Pajala
New data is
presented 20070418 the data is now processed and recalculated. The numbers is
corrected with a factor for horizontally used sonar, the number corrects the
fish target strength so we are now able to use the –29 dB (29 dB represent a fish 63 cm big (Lilja
2004)) as the limit for salmon and other species. During the summer 2006 the
limit was set to –27 dB (fish longer than 80 cm).
In the
tables below we present number for down streams moving fish that is calculated
as 32% of the fish that is mowing up streams. Witch was the actual number for
fish bigger than 80 cm (TS –27dB) during summer 2006.
Calculation
with the uncovered time and area factors gives us the theoretical maximum
numbers of salmon moving upstream.
The
operating time for the data collecting is 95% from 060612 to 060916
The covered
area is 70 % of the river.
There are
still some corrections to do and this will correct the numbers slightly
Salmons spotted in the beam bigger than 63 cm 


8663 

Theoretical salmon mowing downstream (32,8% of 8663) 

2842 

Salmons moving upstream theoretical minimum 


5821 








Theoretical salmons moving upstream calculated with time and area
factors 
12955 

Theoretical salmons moving downstream calculated with time and area
factors 
4250 

Salmons moving upstream theoretical maximum 


8705 

Average size salmon moving upstream calculated from
sonar data 
86 cm 
6,3 kg 
Average
size salmon calculated from catch reports (Muonio and Kolari fishing areas
2006) 
 cm 
7,0 kg 
Fish that
is longer than approximately 1,4 m does not exist and is a known error when
using sonar horizontally. Some of the fishes are moving so close to another
that the sonar cannot differ the fishes from others and appear as on big target
in sonar screen. There are also some errors with the tilt of the sonar and the
swim directions. This results in that some fish will appear bigger than in
reality. The sum of fish, moving upstream, that is bigger than 1,4 m is
approximately 400.
©
CEITAtech 2006