Abstract
Endemic fish species of Armenian ichthyofauna – the Sevan trout (Salmo ischchan, Kessler, 1877) is registered in the Red Book of Animals of the Republic of Armenia as critically endangered (corresponds to IUCN category: CR A2cd). Its natural reproduction hardly occurs as a result of numerous problems related to the use and management of water and bio-resources in the drainage basin of Lake Sevan. The Lichq River is formerly known as a spawning river for two ecological races of Sevan trout, but because of different factors there are no more wild populations of Sevan trout spawning. The aim of the study was checking the efficiency of two methods of egg incubation in the Lichq River for restoration of Gegarkuni population. The experiments were carried out with newly fertilized and eyed eggs of Gegarkuni in the same periods and in the same areas to avoid the unforeseen effects of environmental factors on assessment. The results showed that the mortality rate of green eggs in the natural conditions is quite high before reaching eyed egg stage (65-68%), while the mortality rate of eyed eggs planted in the natural conditions is only 9-17%. This means that the effectiveness of planting eyed eggs is higher for the artificial restoration of Gegarkuni stocks in the nature.
Highlights
As known, endemic Sevan trout (Salmo ischchan Kessler, 1877) is one of the most economically and culturally valuable representative of Armenian ichthyofauna
There were 4 races of Sevan trout: Summer trout or Summer bakhtak (Salmo ischchan aestivalis, Fortunatov), Gegarkuni (Salmo ischchan Gegarkuni, Kessler), Winter trout (Salmo ischchan ischchan, Kessler) and Bojak (Salmo ischchan danilewskii, Iakowlev) that differ by their reproduction ecology
Carried experiments are shown that the mortality rate of green eggs planted in natural conditions till the eyed egg stage is quite high and reaching 65-68% while the mortality rate of eyed eggs planted in natural conditions is only 9-17%
Summary
Endemic Sevan trout (Salmo ischchan Kessler, 1877) is one of the most economically and culturally valuable representative of Armenian ichthyofauna. Even before 1930’s, when neither Lake Sevan nor Sevan trout stocks had faced the current problems, these races were isolated by spawning areas. According to Fortunatov, lacustrine forms (Winter trout and Bojak trout) usually did not migrate to rivers for spawning [1]. Because the lake water level periodically decreased in the period from 1930s to 2000s, many clues in the shore zone of Lake Sevan became dry and races of Sevan trout, which spawn in the littoral zone of the lake, lost their spawning areas. According to Pavlov, part of Winter trout shoal started to migrate to the rivers of Lake Sevan basin for spawning [2]. According to Smoley, spawning areas of Summer trout in the littoral zone
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