International Journal of Aquaculture, 2018, Vol.8, No.16, 121-126
124
2.3 Comparative analysis of the growth rate
The studied population of
S. trutta
from Iliyna River has relatively fast temp of growth. Arranging the 20
populations of the species in ascending order of the fish lengths at the same age, the population from Iliyna River
takes 7
th
position (Table 4). Table 5 and Table 6 present comparison between the parameters from the von
Bertalanffy’s linear and weight growth equations, φ’ and ω parameters for the brown trout from different rivers in
Bulgaria. The smallest asymptotic length (L
∞
, cm) and weight (W
∞
, g), and respectively the highest growth
constant (k) are established for
S. trutta
from Iliyna River. The changes in the parameters φ’ and ω doesn’t show
clear tendency.
Table 4 Linear growth rate of
S. trutta
from different rivers
River/Author
Fish length (L, cm) by age (years)
1
2
3
4
5
6
7
8
Hincov (Kirka, 1964)
6.2
7.8
10.4
12.6
15.3
Beli Iskar (Yankov, 1988)
9.5
15.7
Dee (Lees, 1972)
6
9.4
13.7
17.3
20.5
23.5
25
24
Raise Beck (Frost, 1954)
5.3
11.2
14.5
17.8
Aspropotamos (Papageorgiou et al,, 1983)
7.9
12.1
15.5
18.3
20.4
22.5
24.1
24.9
Upper Tees (Crisp, 1963)
4.8
9.7
13.5
16.5
19.8
21.6
23.9
25.9
Iliyna (our data)
6.3
13
15.7
18.8
20.8
Boca (Kirka, 1969)
7.3
13.1
16.9
21.1
22.8
Rilska (Yankov, 1988)
10.3
14.9
18.1
20.8
22.9
24.8
Zavodna (Yankov, 1988)
9.5
14.8
17.5
20.5
Iliyna (Yankov, 1988)
9.8
15.2
18.7
20.6
Dosnika (Georgiev, 1978)
8.6
15.4
19.1
22
24.7
26.5
27.7
Loucka (Libosvarsky, 1968)
10.3
17.2
19.9
22
25.1
Bela Mesta (Yankov, 1988)
10.1
15.6
17.7
21.9
26.7
31.3
34.3
Rivers in Rodopi mountain (Belcheva, 1959)
5.6
11.7
15.4
22.1
Malyovishka (Yankov, 1988)
10.5
13.7
20
Chwefru (Milner et al, 1978)
8.3
15.8
20.8
Biela Orava (Holcik, 1974)
8.2
14.5
22.4
23.9
Duhoun (Milner et al, 1978)
7.6
14.4
19.3
24.6
Trigradska (Yankov, 1988 )
11.6
17.6
22.7
25.1
28.1
Table 5 Parameters L
∞
(cm), k, t
o
(years) from the linear growth equation of von Bertalanffy, growth index φ’ and ω parameter for the
brown trout (
S. trutta
) from different rivers
River/Author
L
∞
(cm)
k
ω
φ
t
o
r
SD
Iliyna River (our data)
23.16
0.4666
10.81
2.40
0.3810
0.994
6.87
Р. Chaya (Yankov, 1988)
32.00
0.4736
15.16
2.69
0.2386
0.997
4.37
Р. Vacha (Yankov, 1988)
41.00
0.2352
9.64
2.60
-0.3349
0.998
3.14
Р. Iskar (Yankov, 1988)
45.5
0.1623
7.38
2.53
-0.7783
0.996
3.62
Р. Mesta (Yankov, 1988)
45.5
0.1604
7.30
2.52
-0.6212
0.998
3.14
Р. Struma (Yankov, 1988)
34.5
0.2330
8.04
2.44
-0.4989
0.996
3.12
Р. Vit (Yankov, 1988)
30.00
0.2607
7.82
2.37
-0.4840
0.998
2.40
3 Discussion
Growth is a bio-energetic process and is defined as a change in the length and weight over a period of time. It
indicates the health of the population and has been extensively studied for various species of fishes (Khan and
Khan, 2014).
