International Journal of Aquaculture, 2018, Vol.8, No.16, 121-126
121
Research Report Open Access
Growth Rate of the Brown Trout (
Salmo trutta
Linnaeus, 1758) from the River
Iliyna, Bulgaria
Galerida Raikova-Petrova, Desislava Rozdina , Radoslav Valkanov
Sofia University “St. Kliment Ohridski”, Faculty of Biology, Department of General and Applied Hydrobiology, 1164 Sofia, 8 Dragan Tsankov Blvd., Bulgaria
Corresponding author Email
International Journal of Aquaculture, 2018, Vol.8, No.16 doi
Received: 17 May, 2018
Accepted: 29 May, 2018
Published: 22 Jun., 2018
Copyright © 2018
Raikova-Petrova et al., This is an open access article published under the terms of the Creative Commons Attribution License, which
permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Raikova-Petrova G., Rozdina D., and Valkanov R., 2018, Growth rate of the brown trout (
Salmo trutta
Linnaeus, 1758) from the river Iliyna, Bulgaria,
International Journal of Aquaculture, 8(16): 121-126 (doi
Abstract
The growth rate of the brown trout (
Salmo trutta
) from Iliyna River, Bulgaria was studied. The relation between the fish
length (L) and scale radius (R) is described by the equation L=12.067R+1.4829, r=0.94. The relation between the length and the
weight (W) is described from the equation W=0.0162L
2.9444
, r=0.999. With the increase of the fish age, the average annual
increments are changing irregularly. The highest length increment occurs during the second year (6.71 cm) and the smallest during
the fifth year (1.96 cm). The highest weight increment was established for the fourth year = 37.91 g. The population of
S. trutta
from
Iliyna River has relatively fast temp of growth. The von Bertalanffy’s linear and weight growth equations are as follows: L
t
=23.16
[1-e
-0.4666 (t-0.38)
], r=0.995, SD=6.8 and W
t
=160.692 [1-e
-0.4978 (t-0.4164)
]
2.94
, r=0.998, SD=7.15.
Keywords
Salmo trutta
; Growth; Bulgaria
Background
Salmo trutta
is a native freshwater fish species for almost all the Europe belonging to the family Salmonidae. It is
widespread and overall Least Concern. Its preferred habitat are cold streams, rivers and lakes. Spawns in rivers
and streams with swift water. The phylogeographic structure is almost destroyed by stocking. Spawning sites are
usually characterized by downward movement of water into gravel. Spawns between late October and March,
usually in November-December (Freyhof, 2011). In small streams, brown trout are important predators of
macroinvertebrates, and declining brown trout populations in these specific areas affect the entire aquatic food
web
/). The brown
trout has been popular subject to angling for centuries in Europe, and in Bulgaria, it is one of the preferred quarry
for the anglers. Even though
S. trutta
occurs in high-mountain Rivers its populations suffer from severe
anthropogenic influence such as pollution, habitat destruction, angling and poacher activities, and etc. That is why
it is very important the status of the brown trout’s populations to be periodically checked. Determination of the
growth rate is very important in inchthyological investigations as fish growth is one of the main factors that
determine stock conditions (Mikhailov and Prodanov, 1983). Growth is perhaps the most studied of all parameters
used to describe the life history of exploited fish (Khan and Khan, 2014). The growth rate of fish populations is
related to the environment conditions and is indicative for the status of the populations. The good water quality
determines the good growth rate of the fish. Contemporary studies on the biology and growth rate of
S. trutta
in
Bulgaria are missing. The Valley of the studied Iliyna River is part of the National Park “Rila” and Natura 2000
site “Rilski monastery”in Bulgaria.
The aim of the study was to establish the growth rate of the brown trout from Iliyna River in Bulgaria and to
compare it with the growth rates of other populations from the area of distribution of the species.
1 Materials and Methods
The material was collected in the autumn 2011 by electrofishing with 700 A/50-70 Hz straight, pulsating current.
Two sampling sites along the river, with the following coordinates were studied: 1. N 42
.
09592°E 023.40512°; 2.
N 42.10099°E 023.34944°. During the sampling the water temperature, oxygen saturation, conductivity and pH
were measured (Table 1). Altogether 38 brown trout specimens from Iliyna River were analyzed. Each specimen
