Coregonus Lavaretus Research Articles

Biological characteristics of whitefish (Coregonus lavaretus L.) in Lake Vishtynetskoye (Kaliningrad region) in the modern period

Biological characteristics of whitefish (Coregonus lavaretus L.) in Lake Vishtynetskoye (Kaliningrad region) in the modern period

Assessment of the Health Status of Whitefish (Coregonus lavaretus Linnaeus, 1758) and the Quality of Its Habitat in Lake Sevan (Armenia) Using a Multi-Biomarker Approach

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.

Gone with the flow: Whitefish egg drift in relation to substrate coarseness under a range of flow velocities.

Most major rivers in Europe have been dammed for hydropower or other purposes. Such river alterations have decimated natural reproduction of many migratory fish species, including that of the anadromous European whitefish, Coregonus lavaretus, which is now maintained by extensive stocking programmes. In addition to stocking, limited natural reproduction may occur downstream of dams, where peak flow bouts from the dams threaten to flush the eggs into unsuitable habitats. Here, we assessed the effects of water flow velocity and substrate coarseness on downstream drift of whitefish eggs under laboratory conditions. The experiment's two different gravel substrates retained eggs better than cobble or sand substrates; the water velocity needed for notable egg drift was higher for the gravel substrates. The results indicate that egg drift is one of the factors that should be considered when evaluating the effects of hydropower plant operations. Moreover, measures mitigating the effects of the artificial flow regimes should incorporate the type and coarseness of the riverbed's substrate.

Условия среды обитания, режим рыболовства и состояние популя-ции сига Coregonus lavaretus (L.) Топо-Пяозерского водохранилища (водосбор Белого моря)

This work is the result of hydrobiological and ichthyological work of the Institute of Water Problems of the North of the Karelian Scientific Center of the Russian Academy of Sciences during the implementation of various topics (governmental and economic-contractual) in the water area of the Topo-Pyaozersky (Kuma) reservoir. The main object of discussion of the article is the whitefish Coregonus lavaretus (L.), namely the state of its population. Calculations of its abundance and biomass in the current study period have been carried out. Taking into account that the nature of commercial production and its unilateral orientation on the part of registered and unregistered fish harvesters remain at a high level, limiting the catch of whitefish should remain an indispensable condition for the preservation and stability of their biological resources. To carry out this catch, it is necessary to carry out a number of measures, in terms of more complete fishing on the main sections of the lake and the conservation of caught fish. As additional measures for this, it is advisable to introduce a ban on whitefish fishing in areas with the largest concentrations during the spawning period. Summary of all the above – whitefish fishing is currently being carried out against the background of a new man-made situation affecting its products, previously modified by other anthropogenic factors. All this exacerbates the problem of fisheries regulation, because other anthropogenic factors often turn out to be unstable and fluctuate (including dramatically) both by year and by season. For example, water levels during the spawning period may vary significantly due to the activities of the Kama HPP, determined by the interests of electricity consumers. As a result, optimal catch rates were calculated – up to 24 tons, or 21.7% of the value of the fishing stock (with a maximum withdrawal of 23.4%).

Effect of anti-adhesive supplement doses on sperm motility characteristics in the European whitefish (Coregonus lavaretus)

Sperm adhering to glass slides is one of the main problems during fish sperm motility analyses with CASA systems. To mitigate this, albumin is the supplement added most frequently to activating solutions. However, there is no data on the use of supplements other than albumin (in various concentrations) in analyses of European whitefish (Coregonus lavaretus) sperm motility. This issue was investigated in the presented research using three anti-adhesive supplements (albumin, casein, Pluronic F-127) that were added to Billard solution (BS: 20 mM Tris, 1 mM CaCl2, 154 mM NaCl, 30 mM glycine at pH 9.0) at different concentrations (0.0; 0.1; 0.2; 0.5; 1.0; 2.0%). It was noted that the addition of the lowest concentration (0.1%) of albumin, casein, or the pluronic to BS had a significant effect on the motility and kinetic parameters of whitefish sperm compared to pure BS. BS supplemented with 0.2–0.5% albumin was the most appropriate variant used for whitefish sperm motility activation in the present experiment. BS supplemented with the pluronic at 1.0–2.0% concentrations resulted in significantly higher values of almost all CASA parameters compared to casein at the same concentrations. Moreover, CASA parameters determined in this variant of the pluronic (1.0–2.0%) were similar to those when BS was supplemented with the same albumin concentrations. This indicated that instead of albumin, the pluronic at higher concentrations in BS might be used to analyze whitefish sperm motility.

Long-term decline of whitefish (Coregonus lavaretus) population in the boreal lake Pyhäjärvi, southwest Finland, relative to simultaneous abiotic and biotic changes

In recent decades many lake fish populations have faced complex pressures particularly due to climate warming and eutrophication. In Lake Pyhäjärvi, southwest Finland, profound changes have occurred in the commercial winter fisheries targeting the coregonids vendace, Coregonus albula, and whitefish, Coregonus lavaretus. The responses of vendace have been examined earlier, and here the detailed analyses are extended to the whitefish. In the 1970s and 1980s, the coregonid fishery was sustainable, but in 1991–1998, intense exploitation led to recruitment overfishing of vendace. Despite temporarily improved growth and recruitment of whitefish during vendace decline, whitefish population biomass declined throughout the study period, while perch (Perca fluviatilis), roach (Rutilus rutilus) and ruffe (Gymnocephalus cernuus) increased and vendace and smelt (Osmerus eperlanus) maintained their abundance. As many other northern lakes, Pyhäjärvi seems to be changing from coregonid to perch dominance due to climate warming and eutrophication. Whitefish decline was associated with decreases in fecundity, winter survival of embryos, and larval density. The spawning stock was kept small by intensive fishery. The decline of the relative fecundity was likely due to food competition with vendace and especially the perch and roach populations that increased with eutrophication and more frequent hot summers. The winter survival of whitefish embryos decreased when the introduced signal crayfish (Pacifastacus leniusculus) increased. Despite decreasing fishing effort in the 2000s the larval numbers continued to decline. In the prevailing circumstances in Pyhäjärvi, whitefish will with high probability remain as a minor and still declining species of the fish assemblage.

The effect of water level changes on the density of newly hatched European whitefish (Coregonus lavaretus (L.)) larvae in unregulated and regulated lakes

The effect of the water levels during the period from spawning to hatching of whitefish (Coregonus lavaretus (L.)) on the density of newly hatched larvae was examined from a 23-year time series. The density of larvae was estimated in four lakes with contrasting water level regulation regimes in Central Finland using depth zone stratified bongo and tube net sampling in 2000–2022 and 2008–2022. In the regulated Tehinselkä, larval density was also modeled as a function of the whitefish spawning stock, vendace stock indices, and water levels. Larger water level maximum drops during winter were observed in three regulated lakes (41–68 cm) than in the unregulated lake (35 cm). The average larval densities were highest in the unregulated Lake Southern Konnevesi and regulated Tehinselkä, with densities >20 individuals ha−1. The regulated lakes Ruotsalainen and Puula had lower average densities, <10 individuals ha−1. Significant synchrony in the inter-annual variation in the density time series was observed between Tehinselkä and S. Konnevesi as well as Tehinselkä and Ruotsalainen. None of studied water level variables were associated with larval density in any lake. Thus, the small-scale regulation in these Finnish lakes did not show any direct effects on the production of whitefish larvae. Our analysis did not provide information on the potential effects of water level regulation on later life. For example, it did not cover the impact on whitefish food resources or the abundance of competitors and predators regulating whitefish growth and mortality in the juvenile stage.

Impact of fishing activities on the population dynamics of European whitefish in four peri-alpine lakes

Inland fisheries play a crucial role in socio-economic activities and food production. However, these fisheries are often less intensively monitored and studied than marine fisheries. In the past two decades, important fluctuations in European whitefish (Coregonus lavaretus) landings have been observed in four peri-alpine lakes in France and Switzerland. To better gauge the impact of fishing removal, a multi-lakes Delay-Difference model was developed and adapted to these fisheries. A hierarchical state-space Bayesian framework was used to integrate stochasticity for each process and incorporate diverse data. The model gave estimates of time series for biomass, recruitment, stage-structured landings, and fishing mortality, as well as estimates of natural mortality rate, Brody growth coefficient and mean recruitment productivity. Differences in the estimates of variables predicted by the model were observed among lakes. Negative impacts of exploitation have been highlighted for Lakes Geneva, Bourget, and Annecy. Low levels of biomass under high fishing mortality rates were observed, while landings tended to increase under lower mortality rates. Lakes Geneva and Bourget outputs suggest stocks were impacted by fishing activities and that fishing effort reduction could ultimately increase yields. Lake Annecy abundance and landings trends increased after 2010, suggesting management strategies that focused on effort reduction were successful. Lake Neuchâtel stock abundance was low after 2017 and probably more fragile due to low biomass levels and recruitment. The observed changes in European whitefish biomass cannot be attributed solely to fishing, suggesting that environmental factors may also influence recruitment success alongside the impacts of fishing pressure.

European whitefish Coregonus lavaretus of the Nizhnetulomskoye Reservoir (Tuloma River basin, Murmansk region) and its habitat conditions

The modern biological characteristics of the most common polymorphic species of European whitefish Coregonus lavaretus (L.) in Northern Europe were studied in the conditions of its habitat in the oldest riverbed reservoir in the Murmansk region. A number of features of the functioning of the ecosystem of the Nizhnetulomskoye Reservoir (hereinafter NTR) have been identified, including eutrophication of the reservoir, accompanied by the development of cyanoprokaryotes in phytoplankton communities, including potentially toxic species. The introduction of the Onega smelt Osmerus eperlanus (L.) into the Tuloma River system half a century ago led to the transformation of the structure of the NTR fish community from whitefish-salmon to whitefish-smelt. Whitefish (hereinafter, this species name is only used in regard to the European whitefish) in the NTR are represented by a polymorphic population and, according to length-weight characteristics, belong to the group of medium-sized whitefish of the Murmansk region watercourses with early maturation. Based on the type of feeding, it can be classified as a benthophage with a wide range of consumption of food organisms. The stomach contents of whitefish in the summer-autumn period correlate well with the seasonality of the development of aquatic invertebrates. Artificial feeds used by the farms of rainbow trout Oncorhynchus mykiss (Walbaum) in the reservoir are currently of great importance in the feeding of the NTR whitefish. Understanding the mechanisms of structural and functional differentiation of whitefish populations is both of fundamental importance in revealing the mechanisms and direction of microevolution and adaptation of fish in changing environmental conditions and of fundamental practical importance in the implementation of protection and rational fishing, their artificial reproduction.

Breeding of whitefish Coregonus Lavaretus L. at the Knyazhegubsky fish hatchery

The article describes whitefish Coregonus lavaretus L., 1758 (Baltic environmental type) breeding results at the Knyazhegubsky fish hatchery (Murmansk region, Russia). Since 2017, the major goal of this fish hatchery has been the breeding of freshwater type of whitefish. Technology for whitefish breeding was tested in 2018-2019. A number of problems encountered by fish breeders were identified. Live fertilized Baltic whitefish eggs at the “eye pigmentation” phase are purchased every year from OOO “Forvat” fish farm (Sosnovo settlement, Priozersky district, Leningrad region, Russia) and transported to the Knyazhegubsky fish hatchery. Major fish-farming activities subsequently performed at the fish hatchery include: eggs incubation in Weiss machines, summer and winter rearing of juveniles in rearing facilities, in trout ditches, and at equipped summer site as well as release of young whitefish aged under one year into the Kovdozerskoe water reservoir. The average mass of a single young fish in the first batch released in 2019 was 0.5 grams. Juvenile fish is available for release on a partial basis into water bodies of the Murmansk region for fish-stocking purposes under contracts with business entities. Currently, technology is being worked on for rearing and formation of the breeding stock. In general, the results of the work performed indicate that Baltic whitefish (freshwater type) rearing conditions at the Knyazhegubsky fish hatchery are favorable.

The Causes of Morphological and Genetic Heterogeneity in the White Fish Coregonus lavaretus Sensu Lato from the Arctic Part of the Lena River Basin

The Causes of Morphological and Genetic Heterogeneity in the White Fish Coregonus lavaretus Sensu Lato from the Arctic Part of the Lena River Basin

Metapopulation Structure of Two Species of Pikeworm (Triaenophorus, Cestoda) Parasitizing the Postglacial Fish Community in an Oligotrophic Lake.

In the present study, we estimated the levels of infestation of the main fish species that are hosts for two Triaenophorus species: T. crassus and T. nodulosus. The prevalence of T. crassus and T. nodulosus infestations in the intestine of their definitive host-pike Esox lucius was similar (71.0% and 77.4%, respectively). At the same time, the prevalence of T. crassus infestation in muscle tissue was significantly different between the second intermediate hosts, Coregonus lavaretus pidschian (31.4%) and Cor. l. pravdinellus (91.2%), due to considerable differences in their diets. For T. nodulosus, we found significant variations in the levels of prevalence among the second intermediate hosts-100% for Lota lota, 81.8% for Cottus sibiricus 31.9% for Thymallus arcticus, and 24.5% for Perca fluviatilis-that we also explained using different diets. Moreover, analysis of the symmetry of parasite infestations did not reveal any asymmetry between the number of cysts in the left and right body surfaces of the "planktivorous" form/species of whitefish, whereas in the ''benthivorous", an asymmetry of parasite infestations was found.

Extinction risks and threats facing the freshwater fishes of Britain

Abstract Extinctions occur naturally in all environments, but rates have accelerated rapidly during the Anthropocene, especially in fresh water. Despite supporting many fish species of conservation importance, there has never been a formal assessment of their extinction risks in Britain, which has impeded their inclusion in relevant legislation and policy. This study therefore used the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species™ Categories and Criteria to conduct the first systematic assessment of the extinction risks and threats facing the native freshwater and diadromous fishes of Britain. In addition, national assessments were produced for England, Scotland and Wales, reflecting the level at which environmental policy decisions are taken in Britain. Seven species were categorized as being threatened with extinction at the regional level, with European eel Anguilla anguilla and allis shad Alosa alosa classified as Critically Endangered, Atlantic salmon Salmo salar, vendace Coregonus albula and European whitefish Coregonus lavaretus classified as Endangered, and Arctic charr Salvelinus alpinus and twaite shad Alosa fallax classified as Vulnerable. In addition, burbot Lota lota was classified as Regionally Extinct, ferox trout Salmo ferox was categorized as Data Deficient, and 25 species were categorized as Least Concern. European sturgeon Acipenser sturio and houting Coregonus oxyrinchus, although probably native, qualified as only vagrants in fresh water, so were categorized as Not Applicable. The assessments provide objective baselines against which future changes can be determined, and a key evidence base to support policy and management decisions for the conservation of freshwater and diadromous fish species and their habitats in Britain. It is recommended that the assessments are repeated every 10 years, which would enable changes in conservation status, the effectiveness of policies and where targeted interventions may be required to be examined using the Red List Index.

Population Structure of European Whitefish Coregonus lavaretus (Salmonidae: Coregoninae) from the Lake–River System of the Subpolar Urals

This paper presents the first description of the population structure of sparsely rakered whitefish Coregonus lavaretus, which lives in the mountain lake–river system of the middle reaches of the Maly Patok River (a second order tributary of the Pechora River). It has been established that European whitefish has formed a complex system of local groups here, which are associated with small lakes of different types, located on the catchment area of this river. A relatively isolated whitefish lacustrine group, which differs in the pattern of the population dynamics and a rapid linear growth of individuals, has been formed in one of the water bodies. There is a temporary aggregation of whitefish in a small endorheic lake, which is recruited only in years with a very high water level during floods. The results of the study of the linear growth indicate the interrelationship between different groups of floodplain–river whitefish from the Maly Patok River basin.

The Ecosystem of Lake Tolpanjärvi, Western Karelia, Preserved in Natural State

The results of the study of Lake Tolpanjärvi’s ecosystem are reported. Its hydrological and geochemical indices, as well as the current condition of biotic communities (zooplankton, benthos and fish population), were studied and analyzed. Analysis of the chemical composition of water indicates the low organic matter content (total phosphorus 0.007 mg/l, nitrogen 0.26 mg/l) of the lake. The Tolpanjärvi is an oligotrophic lake, as indicated by the abundance of zooplankton (with a biomass of less than 1 g/m3) and zoobenthos (biomass 0.44 g/m2). The lake is of an oligosaprobic class (2nd quality class, clean natural water), as evidenced by its saprobity index estimated using Pantle–Bukk’s method. The quantitative indices of zoobenthos varied from 120 individuals/m2 and 0.08 g/m2 in the profundal zone to 1200 inds./м2 and 0.86 g/m2 in the quiet littoral zone. The lake is more similar in the chironomid index (К – 2.00) to clean natural water. It is inhabited by 8 fish species of 5 families. The fish population is dominated by the whitefish Coregonus lavaretus, the perch Perca fluviatilis and the roach Rutilus rutilus. Two ecological forms of whitefish, differing in both the number of gill rakers (sparsely-rakered 18–24 and medium-rakered 28–36) and biological indices (linear-weight growth рост, maturation, fertility and feeding), occur in the lake. Stable highly diverse ecosystems were shown to form the basis for the preservation of the gene pool and for assessment of the current condition of water bodies heavily affected by human activities.

Состояние экосистемы озера Хедо (западная Карелия) в условиях рыбоводной деятельности

The article highlights the analyzes of the ecosystem of Lake Khedo (Republic of Karelia) under conditions of growing anthropogenic load caused by using the lake for breeding trout in fish cages based on the proper and literature data. Comparative analysis of hydrochemical data before the operation of the farm (until 2005) and after showed a twofold increase in water color (70-150°), which indicates an increased content of organic pollutants (humus, peat, silt). Also in the reservoir there are increased nitrogen and phosphorus compounds. Previously, the concentration of total phosphorus did not exceed 0.01 mg/l, today it reaches 0.02 mg/l. The main factor contributing to the satisfactory state of Lake Khedo is the high water flow rate, due to which most biogens are flown outside the lake. The data on the main hydrobiological indicators of the lake (phytozooplankton and zoobenthos) are presented. It has been stated that if earlier the reservoir corresponded to the mesohumous oligotrophic type, at present it reaches the initial level of mesotrophy, which is probably facilitated by the long-term cage cultivation of the aquaculture object. In terms of the abundance of organisms of the initial trophic levels, the reservoir corresponds to α-mesotrophic type. The lake is inhabited by 8 species of fish, and the valuable ones include whitefish Coregonus lavaretus (L.) and vendace Coregonus albula (L.). The results of the research made it possible to clarify the total production of commercial trout, which amounted to 300 tons per year and doesn’t exceed the total biogenic load. Recommendations on timing the regular ecological expertise of the lake and the adjustment of production volumes are given

Contaminants reach everywhere: Fish dietary samples should be surface decontaminated prior to molecular diet analysis.

Knowledge of trophic interaction is necessary to understand the dynamics of ecosystems and develop ecosystem-based management. The key data to measure these interactions should come from large-scale diet analyses with good taxonomic resolution. To that end, molecular methods that analyze prey DNA from guts and feces provide high-resolution dietary taxonomic data. However, molecular diet analysis may also produce unreliable results if the samples are contaminated by external sources of DNA. Employing the freshwater European whitefish (Coregonus lavaretus) as a tracer for sample contamination, we studied the possible route of whitefish in beaked redfish (Sebastes mentella) guts sampled in the Barents Sea. We used whitefish-specific COI primers for diagnostic analysis, and fish-specific 12S and metazoa-specific COI primers for metabarcoding analyses of intestine and stomach contents of fish samples that were either not cleaned, water cleaned, or bleach cleaned after being in contact with whitefish. Both the diagnostic and COI metabarcoding revealed clear positive effects of cleaning samples as whitefish were detected in significantly higher numbers of uncleaned samples compared to water or bleach-cleaned samples. Stomachs were more susceptible to contamination than intestines and bleach cleaning reduced the frequency of whitefish contamination. Also, the metabarcoding approach detected significantly more reads of whitefish in the stomach than in intestine samples. The diagnostic analysis and COI metabarcoding detected contaminants in a higher and comparable number of gut samples than the 12S-based approach. Our study underlines thus the importance of surface decontamination of aquatic samples to obtain reliable diet information from molecular data.

БИОХИМИЧЕСКИЕ ПРОЦЕССЫ В ТКАНЯХ ГИДРОБИОНТОВ КАК МАРКЕРЫ ОКИСЛИТЕЛЬНОГО СТРЕССА ПРИ БИОМОНИТОРИНГЕ АНТРОПОГЕННОГО ВОЗДЕЙСТВИЯ НА ВОДНЫЕ ЭКОСИСТЕМЫ

The results of the study of the content of malondialdehyde (MDA), reduced glutathione, the activity of glutathione reductase of hydrobionts for the identification of oxidative stress when exposed to the extract of bottom soils of the Northern Dvina River are presented. The tissues of the common whitefish (Coregonus lavaretus) selected as part of annual monitoring studies and samples of the test culture of the danio culture (Danio rerio) were used. The results revealed differences in the levels of markers in various whitefish tissues: the highest concentrations of markers were recorded in the liver. An experiment with a test culture showed an increase in oxidative stress when exposed to bottom soil extracts, manifested in a change in the levels of marker indicators in danio fish.

Trophic diversification and parasitic invasion as ecological niche modulators for gut microbiota of whitefish.

The impact of parasites on gut microbiota of the host is well documented, but the role of the relationship between the parasite and the host in the formation of the microbiota is poorly understood. This study has focused on the influence that trophic behavior and resulting parasitism has on the structure of the microbiome. Using 16S amplicon sequencing and newly developed methodological approaches, we characterize the gut microbiota of the sympatric pair of whitefish Coregonus lavaretus complex and the associated microbiota of cestodes parasitizing their intestine. The essence of the proposed approaches is, firstly, to use the method of successive washes of the microbiota from the cestode's surfaces to analyze the degree of bacterial association to the tegument of the parasite. Secondly, to use a method combining the sampling of intestinal content and mucosa with the washout procedure from the mucosa to understand the real structure of the fish gut microbiota. Our results demonstrate that additional microbial community in the intestine are formed by the parasitic helminths that caused the restructuring of the microbiota in infected fish compared to those uninfected. Using the desorption method in Ringer's solution, we have demonstrated that Proteocephalus sp. cestodes possess their own microbial community which is put together from "surface" bacteria, and bacteria which are weakly and strongly associated with the tegument, bacteria obtained after treatment of the tegument with detergent, and bacteria obtained after removal of the tegument from the cestodes.

The Contact Zone of Phylogenetic Lineages of Freshwater Fish in Arctic Eurasia: Genetic Polymorphism of Coregonid Populations

The reconstruction of regional fauna history is very important in the context of recent climate change and anthropogenic transformation. We analyzed the mitochondrial nd1 gene polymorphism in populations of whitefish Coregonus lavaretus and certain widespread Eurasian ciscoes species: vendace Coregonus albula and least cisco Coregonus sardinella, inhabiting waterbodies from the Anadyr River in the east (the Pacific Ocean basin) to Loch Lomond in the west (the Atlantic Ocean basin). Distinct phylogenetic lineages and secondary contact zones have been found in these species. Most of these are species-specific with the exception of the zone from the Pechora River basin to at least the western part of the Taymyr Peninsula, in which whitefish, vendace, and least cisco share with each other and with various cold-water hydrobionts. We associate differences in the geographical position and propagation of the secondary contact regions with the species-specific morpho-ecological features, in particular, with the ability for long-term migrations. Based on the data obtained, we also discuss certain limitations of the phylogeography and phylogeny of the considered coregonid species and the correctness of the taxonomic status of certain populations or their groups.