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Evaluation of trout farms impact upon river water quality in Northern Poland
Goryczko K.,* Sobocinski Z.,** Telezynski A.
*Polish Trout Breeders Associacion, Rutki, 83-330 Zukowo, Poland, ** Gdansk Water Fundation, Rycerska 9, 80-882 Gdansk, Poland
 The general aim of research co-sponsored by Provincional Environment Protection and Water Management Fund in Gdańsk and Polish Trout Breeders Association was to evaluate the pollution from trout farms and its impact on the river water quality.
The region was chosen due to the concentration of trout farms that cover up to 70% of Poland’s trout production.
The research was realised by the independent body, the Gdańsk Water Foundation.
In 2001,seven farms were monitored in August and September when the combination of the adverse conditions of high temperatures, low water flow and high biomass occurs. In all farms water from fish ponds flows through sedimentation ponds or lagoons (see photographs).
Water samples were taken by automatic sampler 6 times during 24 hour period during 3 consecutive days.
Inflow and outflow water was characterized by: suspended solids (SS), chemical oxygen demand (COD), biological oxygen demand (BOD5), nitrates (N-NH4), total ammonia (NT) and total phosphorus (PT ).
Water inflow was measured using a hydrometric counter. The actual fish biomass and total water volume in the farm whole facilities were calculated. These data enabled to asses the water retention time and fish biomass (kg) per inflow water (m3/h) ratio (BIW).
The results are presented in Table 1 below.
Table 1. The mean values of difference in concentration of some pollution indicators (mg/l) between inflow and outflow in monitored farms.
|
|
Biomass T
|
Inflow m3/h
|
BIW
|
SS
|
COD
|
BOD5
|
N-NH4
|
NTotal
|
Ptotal
|
|
Farm 1
|
3,5
|
183
|
19,1
|
-6,5
|
|
0,4
|
0,298
|
0,10
|
0,05
|
|
Farm 2
|
58
|
1620
|
35,8
|
-15
|
1,3
|
-0,4
|
0,226
|
0,32
|
0,05
|
|
Farm 3
|
111
|
1044
|
106,3
|
-2,7
|
-0,1
|
-0,4
|
0,190
|
0,01
|
0,03
|
|
Farm 4
|
170
|
2093
|
81,2
|
-1,3
|
0,4
|
-0,4
|
0,337
|
0,49
|
0,06
|
|
Farm 5
|
33,1
|
1530
|
21,6
|
0,8
|
1,5
|
0,9
|
0,113
|
0,06
|
0,02
|
|
Farm 6
|
40
|
4476
|
8,9
|
0,2
|
-1,6
|
0,1
|
0,062
|
-0,03
|
0,01
|
|
Farm 7
|
24
|
814
|
29,5
|
-1
|
-2,4
|
-0,7
|
-0,002
|
-0,09
|
-0,01
|
Farms 1, 2 and 3 are located by this same creek; farm 1 is the uppermost, farm 2 is800m below and farm 3 is located 2900m below farm 2. It can be seen that each one reconditions water very effectively, enabling to increase production in consecutive farms two- and three-fold respectively (Table 1).
Taking into account the considerable variability of inflow water quality observed, the necessity for further and more precise monitoring became obvious.
In September 2002, four farms were monitored, this time by sampling inflow and outflow water
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12 times during a 24 hour period,
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followed by a 24 hour beak and then
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once more 12 times during 24 hours .
In each farm the actual fish biomass, the total water volume, including the sedimentation pond, and its retention time were determined. Additionally, the coefficient of fish biomass per total water volume (FBTW) was calculated. The results are presented in Table 2 below
Table 2. Mean diurnal values of difference in concentration of some pollution indicators (mg/l) between inflow and outflow in monitored farms.
|
|
Biomass kg
|
Volume m3
|
Retention h
|
FBTW kg/m3
|
SS
|
COD
|
BOD5
|
N-NH4
|
NTotal
|
Ptotal
|
|
Farm 8
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22520
|
4772
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4,1
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4,7
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-2,7
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0,4
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0,1
|
0,01
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0,09
|
0,005
|
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Farm 9
|
6832
|
895
|
5,0
|
7,6
|
-6,9
|
0,5
|
0,3
|
0,14
|
0,29
|
0,017
|
|
Farm 7
|
195000
|
30578
|
9,4
|
6,4
|
-4,3
|
1,1
|
0,4
|
0,17
|
0,25
|
0,021
|
|
Farm 10
|
35000
|
9375
|
5,2
|
3,7
|
-1,8
|
1,5
|
0,9
|
0,25
|
0,39
|
0,030
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These data were obtained from the different type farms selected purposefully. Farm 8 it is Department of Salmonid Research Rutki (photo 3)
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