Freshwaters worldwide are constantly exploited for their water and biological resources. In addition, restoration and management options may exert additional stress on already threatened hydroecosystems. In such cases, the necessity of estimating the potential natural feed base that can support growing fish stocks becomes urgent. In this work, we suggest a quick method for estimating the potential feed base of fish in a freshwater ecosystem based on the analysis of the diet and feeding habits of fish and the biomass of fish and prey organisms. As a model ecosystem we selected a large mountain freshwater lake with relatively simple trophic relationships, short food web and lack of piscivore species—Lake Sevan (Armenia). Since 2016 the lake has hosted cage-based aquaculture for trout re-stocking purpose. Our results showed that the available biomass of main prey organisms in the model lake could support a far larger fish population. The results also provide a boundary for re-stocking volumes in the lake taking into account the increasing wild stock that can be safely supported by the available natural feed (forage) base. A verification of the method on the available historical data spanning 14 years in total, demonstrated a good correspondence with a past event of massive fish kills when fish starvation led to death. The method can serve as a useful screening tool for efficient management of aquatic ecosystems with simple food web structure with several applications in the fishery management and fish stock restoration.

The endangered endemic species Sevan trout (Salmo ischchan Kessler, 1877) is under the threat of extinction and its survival is dependent on restocking by smolts. Thus, there is an urgent need to find an effective solution for restocking wild populations. After developing a theoretical methodology to reveal the most suitable parts of spawning rivers for natural reproduction, we consider the incubation of eggs in the wild as an appropriate method for the validation of the results of the theoretical assessment. Thus, we estimate the eggs’ survival differences in the wild and microcosm conditions which found significant differences in the sac-fry emergence rate in the zones assessed as “partly suitable” and “unsuitable”. Also, the results show that the emergence of eggs in the wild was less than in the microcosm conditions and the success rate of emergence of eyed eggs in the wild was higher than that of the green eggs. The results of one-way ANOVA, correlation and general linear mixed model analyses have in general proven the theoretical assessment but raise some questions on the completeness of using a set of abiotic criteria as the range of success during different experiments varies significantly.

Given the low efficiency of current actions regarding the restoration of a critically endangered species, the Sevan trout, there is an urgent need for the evaluation of ongoing strategies and prioritization of the most efficient ones. Thus, the aim of this study was the scientific justification of the effectiveness of various restoration strategies for Sevan trout wild stocks. For this, we developed an experimental design to estimate the efficiency of stocking the main spawning rivers with fingerlings. Sevan trout subspecies were released and re-captured to measure their growth rates and biological features. Also, we conducted assessments of the abiotic conditions and ecological status of rivers. Because Sevan trout fingerlings have also been used to directly stock Lake Sevan by the Foundation for “Restoration of Sevan trout stocks and development of aquaculture” in recent years, we set gill nets to capture and study Sevan trout from the lake. The results showed that releasing summer trout less than 1 g in weight into the inlets of Lake Sevan is ineffective. Although larger gegharkuni had higher survival rates, the current state of the rivers will hardly ensure the sustainability of stocks. Current investigations have also shown the viability of stocking into the lake, as supported by both 2+- and 3+-year-old specimens being reported. However, further studies of the spatial dispersion and survival of stocked juvenile trout and the state of spawning grounds in the lake would help improve restoration strategies.

River ecosystems are increasingly vulnerable to intensified human pressures associated with population growth and rising living standards, leading to structural changes and altered ecosystem service (ES) provision. The lower course of the Hrazdan River (Armenia) exemplifies these impacts, as it flows through Yerevan, the capital city, and receives substantial inputs of largely untreated wastewater. To assess resulting changes in ES, this study applies a multi‐method approach combining field‐based ecological assessments with social survey research. This integrated framework enables the comparison of actual ES flows with stakeholder perceptions, capturing both biophysical conditions and societal values. Results reveal a marked discrepancy between perceived and actual ES provision. While regulating and maintenance services are relatively highly prioritised by stakeholders, many essential ecosystem functions remain poorly understood, indicating significant knowledge gaps and limited public engagement. At the same time, the availability and quality of key services are severely degraded, contributing to tensions between stakeholders and decision‐makers. These findings point to persistent management challenges, including mismatches between top–down governance and bottom–up engagement. The study highlights the importance of integrating ecological data with social perspectives to support more effective, inclusive and conservation‐oriented management strategies for heavily impacted river systems.

Lake Sevan is a freshwater reservoir in the Caucasus region. Since the first half of the 20th century, the lake has undergone significant changes caused by human activity and anthropogenic pressure. To identify the current ecological state of two bays—Lchashen and Lichk—located in different parts of the lake, a study was conducted in 2022–2023 using a multi-biomarker approach. For this purpose, biomarkers for assessing the health status of fish and the quality of their living conditions were used such as the activity of acetylcholinesterase (AChE) in the brain, glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), and the concentration of reduced glutathione (RGS) and malondialdehyde (MDA) in the liver and gills of the whitefish (Coregonus lavaretus Linnaeus, 1758). In addition, hydrochemical and ichthyological analyses were conducted. This study demonstrated seasonal dynamics for all biomarkers. Comparative analysis of biomarkers and hydrochemical and ichthyological data showed that the whitefish in Lchashen Bay is in worse health, and its living conditions there are less favorable than in Lichk Bay.

This article presents the first craniometric study of seven wolves sacrificed and buried at an Early Bronze Age sanctuary (28th–26th centuries BCE) in the Mets Sepasar settlement. The study identifies specific craniometric parameters and analyzes morphometric skull variability across a chronological range from the Early Bronze Age to the present day. Comparative analyses were conducted using skull parameters of subfossil dogs and modern wolves from Armenia, sourced from the collections of the Scientific Center of Zoology and Hydroecology of the National Academy of Sciences of the Republic of Armenia. The research establishes ranges of individual variation and highlights differences in cranial size and structure between subfossil and modern representatives of the genus Canis. The wolf skulls from the Mets Sepasar archaeological site represent unique Early Bronze Age material, as they constitute a unique dataset that reflect various aspects of ecology and ritual practices of the time. The results demonstrate similarities in the absolute parameters of subfossil and modern wolves; notably, the subfossil wolves from the Mets Sepasar sanctuary exhibit larger dimensions compared to modern wolves from other regions of Armenia. Furthermore, subfossil dogs were found to be clearly distinct from both modern and subfossil wolves across all measured parameters. These findings enrich the craniological data for the genus Canis, providing valuable comparative material for identifying bone remains in future craniological and zoological research. Such data significantly expands our understanding of the cultural and ecological dimensions of human-wildlife interaction in the past. These results serve as a critical tool for identifying skeletal remains in archaeological excavations and contribute to the reconstruction of Ancient Armenian ecosystems.