The modern condition of rainbow trout Parasalmo mykiss in the
Kolsai lakes
-
1
Kazakh Scientific Research Institute of Fisheries, Kazakhstan
Kolsay lakes are a system of three lakes in the Northern Tien Shan, in the Kolsay gorge connecting the Kungei-Alatau and Zailiyskiy Alatau ridges. The lakes are located on the territory of Raiymbek district of Kazakhstan. They situated approximately 10 km from the border with Kyrgyzstan, in 330 km South-East of Almaty at an altitude 1000 m, 2500 m, 2700 m above sea level. The lakes are called "the pearl of the Northern Tien Shan". They are surrounded by coniferous forest of Tien Shan spruce. The depth of the lakes reaches 50 m. Fish fauna is represented by rainbow trout. Kolsay lakes include 3 lakes: The third lake is located at an altitude 1818 m, length — 1 km, width — 400 m, depth —80 m. Middle (second) Kolsay lake (Mynzhylgy) — is the largest of the three lakes and located at an altitude 2252 m. The first Kolsay lake or Upper Kolsay is at an altitude 2850 m.
Figure 1 – Location of the Kolsai Lakes
Rainbow trout was first imported to Kazakhstan in 1964, from Czechoslovakia with developing caviar. Due to acclimatization, the ichthyofauna of reservoirs was studied, and only the lake Lower Kolsai had native ichthyofauna and was represented by 2 species: the Naked Osman (Diptychus dybowskii Kessler) and the Tibetan loach (Noemacheilus stoliczkai Steindachner), r. Kolsay inhabited the scaly osman, meeting in the lake in single specimens. After acclimatization of rainbow trout, there was a gradual reduction in the numbers of the loach and osman. The naked osman completely disappeared from the ichthyofauna of the lake, while the loach was extremely rare in the lake, and would occasionally be found in the stomach of the trout.
Figure 2 – General view of rainbow trout in the Lower Kolsai
The modern ichthyofauna of the lake Lower Kolsai consists of 2 species: the rainbow trout and Tibetan loach, and the loach was found very rarely, and now it is quite possible that this species disappeared from the ichthyofauna, which was proven by its absence of our collections. The ichthyofauna of the lake Middle Kolsai is represented by one species – the rainbow trout.
We conducted the research in summer from 2011 to 2019 at the Lower and Middle Kolsai lakes.
In the research collections, the number of small individuals were more compared to large individuals. The occurrence of large specimens was rare; they were present in the collections in 2012 and 2019.
The results of the biological analysis showed insignificant differences in the values of biological characteristics. The highest and similar values of fatness according to Fulton have been observed in individuals studied in 2013, 2018 and 2019. In general, the main biological parameters remain stable.
Large specimens are rare and during the study, they were caught: in 2012, the length of rainbow trout in the lake Middle Kolsai was 500 mm, in 2018 and 2019, the length in the lake Lower Kolsai was 545 mm and 500 mm, respectively.
The main food of rainbow trout in the lakes were imagoes and larvae of the insect groups: Coleoptera (beetles), Diptera, Hemiptera, Hymenoptera. Also, depending on the season, the dominant components in trout diet change. This phenomenon is explained by the biological characteristics of the fish – as they react to moving objects, and the seasons of fishing, because the material was collected in the summer, and at this time of year, terrestrial invertebrates are usually abundant. Fatness, according to Fulton, of the individuals studied in lakes testifies to good provision of feeding base.
Rainbow trout in the reservoir reaches maturity at 2-3 years of age. In 2014, most of the fish were in the stage II of gonad maturity, in 2017 and 2018 most of the fish caught were in the stage III. In 2019, the study sample consisted of females of the stage III-IV of maturity, males of the stage V of maturity. Also, we have discovered individuals with improper development of the sexual products.
For the first time in many years after the introduction of rainbow trout in the lake of Lower Kolsai, we give a complete morphometric characteristic of fish. For the morphological analysis were used 29 plastic and 23 meristic characters.
Samples of rainbow trout from the lake Lower Kolsai among themselves significantly (Tst>2.2, which exceeds 5% significance level) differ in two ways. Of these, the countable (number of vertebrae) and plastic (number of branched rays in the pectoral fin).
To assess the quality of the aquatic environment and the degree of impaired developmental stability we used the asymmetry technique. The average frequency of asymmetric manifestation on the signs in the 2018 sample is 0.21 ± 0.07; in the individuals caught in 2017, it is equal 0.19 ± 0.04. The values of the asymmetry index, on a five-point scale, correspond to the first point. The values of the integral asymmetry index, corresponding to the first point, are usually observed in favorable environmental conditions.
Analyzes of the growth and age of fish showed a dominance in the population of young age groups. A possible reason for the absence and low occurrence of large fish in catches is the over-density of the population in the lake. Due to insufficient space, the fish is limited to the maximum growth; although there is evidence that the rainbow trout in good conditions can live up to 11 years.
Thus, the current state of rainbow trout populations remains stable. Biological parameters remain within the normal; no deviations pronounced have been identified. At present, the hydrological characteristic of the reservoir is favorable for the safe existence of the fish population. According to the results of developmental stability, the state of rainbow trout populations is characterized as stable.
Keywords:
Kolsay Lakes,
Modern,
Parasalmo mykiss,
Acclimatization,
ichthyofauna
Conference:
XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019.
Presentation Type:
Poster
Topic:
EVOLUTIONARY GENOMICS OF FISHES
Citation:
Kozhabaeva
EK
(2019). The modern condition of rainbow trout Parasalmo mykiss in the
Kolsai lakes.
Front. Mar. Sci.
Conference Abstract:
XVI European Congress of Ichthyology.
doi: 10.3389/conf.fmars.2019.07.00018
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Received:
25 Jun 2019;
Published Online:
14 Aug 2019.
*
Correspondence:
PhD. Eleonora K Kozhabaeva, Kazakh Scientific Research Institute of Fisheries, Almaty, Kazakhstan, e.b.kozhabaeva@gmail.com