On the problem of ratio of anadromy and residence in salmonids (Salmonidae)

According to published and original data, the anadromy and residence in salmonids (Salmonidae) are considered: within one population; in males and females; in different populations in the area of one species under natural conditions; outside of the natural area, at introduction; types of anadromy and residence in different species; causes and mechanisms of formation of anadromous and resident strategies; and applied consequences in the light of notions on formation of life strategies.     

Distribution of fish and the biotopic structure of the basin of the small salmon river (the Nachilova River,Western Kamchatka)

For one of the small Western Kamchatka rivers, according to the combination of several characteristics (watershed, channel slope, water abundance of the flow, pattern of bottom sediments), the classification of channel processes was performed, and on its basis, six biotopes successively replacing each other from the effluents to the mouth were separated. It was shown that against the background of relatively stable conditions of the summer-autumn period, an independent population of Salmonoidei, an assembly, is formed within each biotope. This is manifested in specific features of species composition, size and age structure, and the density of populating biotopes. The stability of the distribution of fish population is supported by constant species composition in particular biotopes over three years and by a comparatively high level of residence of the dominant salmon species.     

Patterns and some mechanisms of downstream migration of juvenile salmonids (with reference to the Utkholok and Kalkaveyem rivers in northwestern Kamchatka)

Principal patterns of the downstream migration of juvenile salmonids (Salmonidae) were discovered on the basis of data of three years of observations. It was found that the time of the beginning, the duration, and the scope of the downstream migration in each particular year are determined by a complex of environmental factors. The crucial abiotic factors are the temperature, the water level of the river, and the illumination. The biotic factors comprise the complex trophic factor. The abiotic environmental factors play the leading role in the realization of the downstream migration at the early ontogenetic stages. The role of the biotic environmental factors increases at the late ontogenetic stages. It was demonstrated that the juveniles that perform downstream migrations are a heterogeneous group consisting of fish of different species and specimens at different ontogenetic stages, of various sizes and ages, and those ready for the transition to the marine environment to variable degrees. The analysis of the patterns of the downstream migration allowed us to describe some mechanisms that control the realization of this process.     

A Rare Case of Permanent Introgressive Hybridization in Char of the Genus Salvelinus (Salmonidae: Salmoniformes) in the Utkholok River,Western Kamchatka

Russian Journal of Marine Biology - Hybrids between the whitespotted char Salvelinus leucomaenis and the northern Dolly Varden S. malma malma have been found to regularly occur and exist...     

Morphological and Genetic Heterogeneity of Sockeye Salmon Oncorhynchus nerka (Salmonidae) of Large Lake–River Systems in Eastern and Western Kamchatka

Journal of Ichthyology - The morphological and genetic heterogeneity of sockeye salmon Oncorhynchus nerka (from both the mixed samples and the samples collected in different periods of its mass...     

Comparison of the spectral sensitivity of three species of juvenile salmonids

The spectral sensitivity of chum Oncorhynchus keta , pink Oncorhynchus gorbuscha and masu Oncorhynchus masou masou salmon was measured by the optomotor reaction index in monochromatic light of 400, 440, 480, 520, 560, 600 and 620 nm using an interference filter. The reaction rate of chum salmon was highest at 520 nm but the rates of pink and masu salmon were highest at 560 nm. In addition, a high reaction rate at 400 nm was also observed in masu salmon, suggesting that masu salmon are sensitive to ultraviolet light.     

Parasites of underyearling kamchatka mykiss Parasalmo mykiss mykiss (Osteichithyes:Salmonidae) in the Utkholok River (North-Western Kamchatka)

Eight species of parasites, Apiosoma piscicolum piscicolum, Apatemon sp., Diplostomum sp., Bunoderidae gen. sp., Crepidostomum metoecus, Hysterothylacium gadi aduncum, Salvelinema salmonicola, and Cucullanus truttae had been found in underyearling Kamchatka mykiss (with fork length 28-41 mm) from the Utkholok River, North-Western Kamchatka. Infestation rate of the fishes with each parasite species was rather low. Presence of C. truttae in underyearling Kamchatka mykiss could not be explained by the conceptual model of its life cycle proposed by Moravec (1979). Spatial and temporal isolation of underyearling Kamchatka mykiss and ammocoetes, as the elements of a local food web, suggest that the lamprey larvae do not participate in the transmission of C. truttae to underyearling Kamchatka mykiss.     

Temperature‐dependent competition between juvenile salmonids in small streams

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Phylogeny of salmonids (salmoniformes: Salmonidae) and its molecular dating: Analysis of mtDNA data

Phylogenetic relationships among 41 species of salmonid fish and some aspects of their diversification-time history were studied using the GenBank and original mtDNA data. The position of the root of the Salmonidae phylogenetic tree was uncertain. Among the possible variants, the most reasonable seems to be that in which thymallins are grouped into the same clade as coregonins and the lineage of salmonins occupied a basal position relative to this clade. The genera of Salmoninae formed two distinct clades, i.e., (Brachymystax, Hucho) and (Salmo, Parahucho, (Salvelinus, (Parasalmo, Oncorhynchus)). Furthermore, the genera Parasalmo and Oncorhynchus were reciprocally monophyletic. The congruence of Salmonidae phylogenetic trees obtained using different types of phylogenetic markers is discussed. According to Bayesian dating, ancestral lineages of salmonids and their sister esocoids diverged about 106 million years ago. Sometime after, probably 100–70 million years ago, the salmonid-specific whole genome duplication took place. The divergence of salmonid lineages on the genus level occurred much later, within the time interval of 42–20 million years ago. The main wave of the diversification of salmonids at the species level occurred during the last 12 million years. The possible effect of genome duplication on the Salmonidae diversification pattern is discussed.     

Biology of resident Dolly Varden trout Salvelinus malma (Salmonidae) from a river with increased natural concentration of toxicants and suspension (Eastern volcanic belt of Kamchatka)

Specific biological features of the population of resident Dolly Varden trout Salvelinus malma inhabiting upper reaches of the Falshivaya River whose water in mean water period has natural increased concentration of copper (0.006–0.018 mg/L), zinc (0.061–0.072 mg/L), and suspension (6–8 mg/L) are described. Its spawning was recorded in mouths of tributaries where (unlike the main river) water is not toxic, its mineralization is two times lower, and turbidity does not exceed 1 mg/L. Among juveniles that left the ground, individuals with scoliosis (11%), undeveloped fins (16%), and exophthalmia occur. The numbers of the population are maintained due to early maturation and spawning before the accumulation in the body of a lethal dose of toxicants and critical amount of functional disturbances. In prespawning fish (3+), multiple pathologies of the histological structure of the gills, liver, and spleen up to necroses were recorded. On average, 10% of maturing oocytes in the ovaries are at different stages of apoptosis. The frequency of pathologies correlates with the concentration in the liver of copper, zinc, and sulphur whose concentration significantly increases with an increase in body weight.     

The Spring-Run Ecotype of the Steelhead Trout Parasalmo (Oncorhynchus) mykiss (Walbaum, 1792) (Salmonidae,Salmoniformes) in the Kamchatka Peninsula

Russian Journal of Marine Biology - A seasonal spring-run (vernal) ecotype of the Steelhead Trout Parasalmo (Oncorhynchus) mykiss (Walbaum, 1792) has been found in western Kamchatka for the first...     

Production of juvenile salmonids in small Norwegian streams is affected by agricultural land use

1. We estimated the biomass and production of juvenile anadromous brown trout (Salmo trutta) and Atlantic salmon (Salmo salar) (parr) in 12 streams in the Skagerrak area of Norway to identify controlling environmental factors, such as land‐use and water chemistry. 2. Production estimates correlated positively with fish density in early summer, but not with the size of the catchment. The summer biomass of age‐0 brown trout and Atlantic salmon was smaller than that of age‐1 and constituted 27.4 and 25.7%, respectively, of the total biomass of the two groups. 3. Mean production of brown trout from July to September varied between streams, but in most cases it was below 2 g 100 m^?2 day^?1. Yearly cohort production from age‐0 in July to age‐1 in July was 10 g m^?2 or less, with mean annual production of 1.32 g 100 m^?2 day^?1, equivalent to 4.8 g m^?2 year^?1. The corresponding annual cohort production of Atlantic salmon was 0.38 g 100 m^?2 day^?1 or 1.4 g m^?2 year^?1. Annual production to biomass ratio (P/B) for brown trout of the same cohort in the various streams was between 1.47 and 4.37; the overall mean (±SD) for all streams was 2.25 ± 0.94. Mean turnover rate of Atlantic salmon was 2.73 ± 0.24. 4. Production of 0+ brown trout during the summer correlated significantly with the percentage of agricultural land and forest/bogs in the catchment, with maxima at 20 and 75%, respectively. Age‐0 brown trout production also correlated with concentration of nitrogen and calcium in the water, with maxima at 2.4 and 14 mg L^?1, respectively. 5. The results support the hypothesis that brown trout parr production reflects the quality of their habitat, as indicated by the dome‐shaped relationship between percentage of agricultural land and the concentration of nitrogen and calcium in the water.     

Phylogeny of salmonids (Salmoniformes: Salmonidae) and its molecular dating: Analysis of nuclear RAG1 gene

The phylogenetic relationships among 26 species of salmonid fishes (family Salmonidae) were studied using the RAG1 gene as phylogenetic marker. No unambiguous relationships between thymalllins, coregonins, and salmonins it was possible to establish. It seems likely, that divergence of these lineages took place during rather short time interval (about 3 to 4 million years). The thymallins are thought to be the first separated lineage. The genera of the subfamily Salmoninae form two distinct monophyletic groups, represented by (1) Brachymystax and Hucho and (2) Salmo, Parahucho, Salvelinus, Parasalmo and Oncorhynchus. Ancestral forms of these two evolutionary lineages could diverge at the Oligocene-Miocene boundary (about 24 million years ago). It is suggested that diversification of the main lineages within the second group was rather rapid, and took place in middle Miocene (about 19?C16 million years ago). Moreover, the lineages of Salvelinus, Parasalmo and Oncorhynchus were the latest to diverge. It seems likely that divergence of the Prosopium and Coregonus ancestral lineages occurred during the same time interval.     

Phylogeny of salmonids (Salmoniformes, Salmonidae) and its molecular dating: analysis of nuclear RAG1 gene

The phylogenetic relationships among 26 species of salmonid fishes (family Salmonidae) were studied using the RAG1 gene as phylogenetic marker. No unambiguous relationships between thymallins, coregonins, and salmonins it was possible to establish. It seems likely, that divergence of these lineages took place during rather short time interval (about 3 to 4 million years). The thymallins are thought to be the first radiated lineage. The genera of the subfamily Salmoninae form two distinct monophyletic groups, represented by (1) Brachymystax and Hucho and (2) Salmo, Parahucho, Salvelinus, Parasalmo and Oncorhynchus. Ancestral forms of these two evolutionary lineages could diverge at the Oligocene-Miocene boundary (about 24 million years ago). It is suggested that diversification of the main lineages within the second group was rather rapid, and took place in middle Miocene (about 19-16 million years ago). Moreover, the lineages of Salvelinus, Parasalmo and Oncorhynchus were the latest to diverge. It seems likely that divergence of the Prosopium and Corergouns ancestral lineages occurred during the same time interval.     

Blood-chemistry indicators of nutritional status in juvenile salmonids

Three experiments were performed to determine the effects of food deprivation (21–35 days at 10–12° C) on selected blood-chemistry variables in juvenile salmonids. The experimental groups were laboratory-reared rainbow trout Oncorhynchus mykiss (RBT), laboratory-reared Chinook salmon Oncorhynchus tshawytscha (LCS) and hatchery-reared, actively migrating Chinook salmon (MCS). After fasting, RBT and LCS were refed for 10 days. In fasted fishes, plasma alkaline phosphatase (ALP) activities decreased relatively rapidly, differing significantly ( P ≤ 0·05) from activities in fed control fishes after 1–2 weeks. Total protein (for all groups) and total cholesterol (for RBT and MCS) decreased relative to fed controls after 2–3 weeks, and total calcium (for RBT and MCS) after 3–4 weeks. Plasma ALP activities recovered after 10 days refeeding, but total protein, cholesterol and calcium concentrations did not. Triglyceride concentrations were highly variable and responded significantly to fasting only in the trial with RBT. Concentrations of some variables decreased (glucose and phosphorus) or increased (total magnesium) relative to control values during the initial days or weeks of fasting and then stabilized at new levels. Activities of four metabolic enzymes of intracellular origin (alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase and creatine kinase) did not differ significantly in the plasma of fed and fasted fishes.     

Density, aggregation, and body size of northern pikeminnow preying on juvenile salmonids in a large river

Predation by northern pikeminnow Ptychocheilus oregonensis on juvenile salmonids Oncorhynchus spp. occurred probably during brief feeding bouts since diets were either dominated by salmonids (>80% by weight), or contained other prey types and few salmonids (<5%). In samples where salmonids had been consumed, large rather than small predators were more likely to have captured salmonids. Transects with higher catch-per-unit of effort of predators also had higher incidences of salmonids in predator guts. Predators in two of three reservoir areas were distributed more contagiously if they had preyed recently on salmonids. Spatial and temporal patchiness of salmonid prey may be generating differences in local density, aggregation, and body size of their predators in this large river.     

Comparison of different biological indices for the assessment of river quality: application to the upper river Moselle (France)

The aim of our study was to assess the water quality of the upper Moselle river by using biological indices. Simultaneous physico-chemical surveys were also undertaken from May 1999 to April 2000. Twelve sampling sites were selected in order to provide a wide range of potential pollution. Chemical analysis did not reveal any major problem of pollution. However a lower water quality resulting from domestic pollution was established for some sampling sites. A biological monitoring combining both macroinvertebrates and macrophytes was performed. Biological indices based on plant community structure and macrophyte composition were not pertinent tools, whereas simple indices based on taxonomic richness of particular groups of macroinvertebrates were strongly correlated with several chemical parameters, showing that such simple biological variables should represent powerful indicators of ecosystem degradation.