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In many freshwater ecosystems, carbon dioxide (CO2) is increasing. Unknown are the risks that high CO2 poses for freshwater organisms, especially fish. The objective of this study was to determine how CO2 may influence the growth rate, metabolic rate, feeding rate, and volitional behaviour of young-of-year Arctic charr (Salvelinus alpinus (Linnaeus, 1758)), brook charr (Salvelinus fontinalis (Mitchill, 1814)), and rainbow trout (Oncorhynchus mykiss (Walbaum, 1792)). For this study, fish stayed in control (1100 microatmospheres (µatm)) or elevated (5236 µatm) CO2 levels for 15 days. During this time, metabolic rate and behavioural tests were conducted on alternating days for each treatment. Weight and length of each fish were taken on days 0, 7, and 15. There was no evidence that elevated CO2 affected the growth rate, feeding rate, or behaviour in any of these species. The standard metabolic rate in Arctic charr differed based on CO2 exposure. Therefore, salmonids can withstand short periods of elevated CO2 under these conditions. By comparing closely related species, the implications of this work are more ecologically relevant and will also help industry quantify the effects of high CO2 on young salmonids. [ABSTRACT FROM AUTHOR]

Indicators of the condition factor, growth rate, and quality of the final products of cultivated objects are important parameters for the effective management of cold-water fish farming. These indicators are also used as a way to control the impact of environmental factors on fish, which requires constant research in the context of intensification of the aquaculture sector. The research is aimed at determining the condition factor and the amino acid composition of muscle tissues of Salmo trutta fario (Linnaeus, 1758), Oncorhynchus mykiss (Walbaum, 1792) and Salvelinus fontinalis (Mitchill, 1814) under the conditions of the western region of Ukraine. The results of the condition factor showed that, S. fontinalis had the highest value with 1.52±0.0340, and O. mykiss and S. trutta showed the lowest value with 1.33±0.0361 and 1.26±0.0181, respectively. Food conversion ratios were similar for S. fontinalis and O. mykiss (1.0), whereas S. trutta showed higher values (1.4). The specific growth rate was higher for rainbow trout (1.4) compared to the brook trout (1.32) and brown trout (1.28). The maximum content of protein, total amino acids (TAA), total essential amino acids (TEAA) and nonessential amino acids (TNEAA) were recorded in the brook trout. The muscle tissue of the investigated fish species is a well-balanced source of the nutrition energy in terms of the ratio of total essential to total nonessential amino acids (TEAA:TNEAA ratio). [ABSTRACT FROM AUTHOR]

A survey of trout species was carried out to assess the trout stocks' quality inhabiting the Palena River Basin, one of the most important rivers for recreational angling in Chilean Patagonia. Six sampling campaigns were carried out over 16 selected stretches of the river between February 2012 and June 2013. A total of 912 trout were collected, 57% rainbow trout (Oncorhynchus mykiss), 33.3% brown trout (Salmo trutta), and 9.6% brook trout (Salvelinus fontinalis). Also, one tiger trout (Salmo trutta X Salvelinus fontinalis) (a hybrid between brown and brook trout) was recorded. Results showed that both rainbow trout and brown trout shared the same reaches of the river, with very similar feeding habits, while brook trout inhabited smaller and more enclosed streams. Maturity stages (V-VI) were recorded from the fish sampled over the period spring-summerautumn in the case of rainbow trout; autumn-winter for brook trout, and summer-autumn for brook trout. One of the study's most notable features was the small size of the mature brook trout, reaching 17.5 cm in length for gravid females and 12.4 cm for mature males at age 2+. The maximum age recorded for rainbow and brown trout was 6+, with a maximum length of 69.8 and 58.5cm, respectively, while for brook trout, the maximum age recorded was 3+ for a female with a length of 29.9 cm length and 2+ for a male of 16.6 cm. [ABSTRACT FROM AUTHOR]

Background: The salmon parasite Gyrodactylus salaris Malmberg, 1957 has caused high mortalities in many Atlantic salmon, Salmo salar, populations, mainly in Norway. The parasite is also present in several countries across mainland Europe, principally on rainbow trout, Oncorhynchus mykiss, where infections do not seem to result in mortalities. There are still European countries where there are potential salmonid hosts for G. salaris but where the occurrence of G. salaris is unknown, mainly due to lack of investigations and surveillance. Gyrodactylus salaris is frequently present on rainbow trout in low numbers and pose a risk of infection to local salmonid populations if these fish are subsequently translocated to new localities. Methods: Farmed rainbow trout Oncorhynchus mykiss (n = 340), brook trout, Salvelinus fontinalis (n = 186), and brown trout, Salmo trutta (n = 7), and wild brown trout (n = 10) from one river in Romania were sampled in 2008 and examined for the presence of Gyrodactylus spp. Alltogether 187 specimens of Gyrodactylus spp. were recovered from the fish. A subsample of 76 specimens representing the different fish species and localities were subjected to species identification and genetic characterization through sequencing of the ribosomal internal transcribed spacer 2 (ITS2) and mitochondrial cytochrome c oxidase subunit 1 (cox1). Results: Two species of Gyrodactylus were found, G. salaris and G. truttae Gläser, 1974. This is the first time G. salaris is diagnosed in Romania. Gyrodactylus salaris was found to infect rainbow trout, brown trout and brook trout in eight of the 12 farms examined. The prevalence and intensity of infections were generally low in all farms. Gyrodactylus truttae was present on brook trout in one farm and on wild brown trout in the river studied. This also represents the first record of this parasite in Romania. Analyses of sequences of the cox1 gene of G. salaris from Romania revealed four haplotypes, all previously undescribed. While it is not unlikely that the infections in Romanian fish farms originate directly from imported rainbow trout, the current data is not sufficient to conclude on this and does not exclude that the infections can originate from hosts in the local water systems. The study shows that there are still unknown populations and variants (haplotypes) of G. salaris present in European rainbow trout aquaculture, all or many of them with unknown biological characteristics such as host specificity and virulence. As some strains might be pathogenic to Atlantic salmon, the importance of carrying out surveillance and keeping a high focus on control with import and export of live fish for aquaculture purposes is important. Conclusions: Gyrodactylus salaris and G. truttae are for the first time found on salmonids in Romania. All mitochondrial haplotypes recovered were previously undescribed and this indicates that there is still an unknown diversity of this parasite present in localities not previously examined. The virulence of the haplotypes found in Romania is unknown and requires establishing. [ABSTRACT FROM AUTHOR]

Brook trout (Salvelinus fontinalis) are generally restricted to headwaters in New York tributaries of Lake Ontario. In only a few streams are brook trout abundant in lower stream reaches that are accessible to adult Pacific salmonids migrating from the lake. Consequently, because of the rarity of native brook trout populations in these lower stream reaches it is important to understand how they use stream habitat in sympatry with juvenile Pacific salmonids which are now naturalized in several Lake Ontario tributaries. In this study, we examined the seasonal (spring, summer, and fall) habitat use of brook trout and juvenile steelhead (Oncorhynchus mykiss) in Hart Brook, a tributary of eastern Lake Ontario. We found interspecific, intraspecific, and seasonal variation in habitat use. Subyearling steelhead were associated with faster water velocities than subyearling brook trout and, overall, had the least habitat similarity to the other salmonid groups examined. Overyearling brook trout and yearling steelhead exhibited the greatest degree of habitat selection and habitat selection by all four salmonid groups was greatest in summer. The availability of pool habitat for overyearling salmonids may pose the largest impediment to these species in Hart Brook. [ABSTRACT FROM AUTHOR]

Les introductions de Salmonidés ont été importantes au cours des 60 dernières années dans les lacs et ruisseaux d'altitude des Hautes-Pyrénées. Six espèces de Salmonidés ont été introduites dans des milieux qui, pour la plupart, étaient vierges de populations piscicoles : la truite commune (Salmo trutta L.), la truite arc-en-ciel (Oncorhynchus mykiss Walbaum), l'omble de fontaine (Salvelinus fontinalis Mitchill), l'omble chevalier (Salvelinus alpinus L.), le cristivomer (Salvelinus namaycush Walbaum) et le splake (Salvelinus fontinalis x Salvelinus namaycush). Dans de très nombreux cas, ces introductions ont abouti à des acclimatations. En revanche, les naturalisations sont beaucoup plus rares. Seules les espèces lacustres (cristivomer et omble chevalier) se sont naturalisées dans la majorité des lacs où elles ont été introduites. Les conditions de reproduction constituent le facteur clé permettant d'expliquer la naturalisation des espèces. En ruisseau, il faut y ajouter la compétition avec l'espèce indigène (la truite commune), la pression halieutique ainsi que les conditions hivernales très rigoureuses. Les incidences écologiques des introductions sur les populations de truites communes indigènes sont faibles. En revanche, elles ne sont pas négligeables pour les populations de batraciens. Cette politique d'introduction a largement participé au développement de l'halieutisme dans ces milieux d'altitude. En cela, les introductions ont parfaitement répondu aux objectifs halieutiques qu'on leur avait fixés. L'acquisition de connaissances sur l'ensemble de la chaîne pyrénéenne constitue aujourd'hui une étape incontournable pour une politique de gestion globale des introductions.

The current paper aimed to study the influence of artificial rearing conditions on glycogen quantity for two trout breeds - rainbow trout (Oncorhynchus mykiss - Walbaum, 1792) and brook trout (Salvelinus fontinalis - Richardson, 1836), analysing 40 individuals, 20 individuals from each breed, belonging to Cheiţa trout farm from Neamţ County. The current research is a part of an ample study designed to enlighten the differences of nutritional value for human consumption of trout meat reared in natural and artificial conditions. Trout represent also an important source of carbohydrates, through its reserves of hepatic and muscular glycogen. Glycogen is synthesised in animal organism by the mono-carbohydrates supplied by food, and in the case of an insufficient contribution of alimentary carbohydrates, it is formed from the resulted products of lipids and proteins catabolism. The obtained data resulted at the end of effectuated analysis on hepatic tissue record mean values of 2.325±0.892 g/100g for rainbow trout and of 3.832±0.450 g/100g for brook trout. In the case of muscular tissue were recorded mean values of 0.098±0.016 g/100g for rainbow trout and 0.130±0.044 g/100g for brook trout. Non-uniformity of biological material as regarding the corporal development and implicit of the tracked carbohydrates parameters have a great influence on the results, increasing in a considerable way their variability degree. [ABSTRACT FROM AUTHOR]

This study was initiated to investigate poor survival of stocked Brook Char Salvelinus fontinalis in Wollondibby creek, a tributary of Lake Jindabyne in the south eastern highlands of NSW,Australia. Sampling of the creek following stocking was carried out on two separate occasions by poisoning I 7.6 km, almost the entire length of the creek in 19 sections. Collection of fish was shown to be 78% effective. Five species of fish were present in the creek: Salvelinus fontina!is, Salmo trutta, Oncorhynchus mykiss, Anguilki australis and Ga!axias sp. Population density in terms of numbers of fish per hectare and kilograms of fish per hectare of all species present was determined. Recovery of stocked S. fontinalis was low (0.38% in 1977 and 0. 15% in 1979).; Distribution of salmonid populations in the creek was significantly affected by physical barriers and eel predation, not cormorants as first thought. Eel predation was confirmed by the presence of salmonids in eel stomachs and extensive fin damage as a result of eel attack. Onl~' five S. fontinaiis in the first sampling event and one in the second sampling event had reached angling size (250 mm). It is suggested that stocking of S. fontinalis not be carried out in areas where A. australis occurs and that careful consideration be given to the location of physical barriers in the creek when stocking and the presence of native fish. [ABSTRACT FROM AUTHOR]

Abstract: Rainbow trout (Oncorhynchus mykiss) display longitudinal and developmental shifts in muscle relaxation rate. This study aimed to determine the role of variations in parvalbumin content in modulating muscle relaxation. Parvalbumin is a low molecular weight protein that buffers myoplasmic Ca2+ and enhances muscle relaxation. In some fish, longitudinal variations in muscle relaxation have been linked to variations in the total amount of parvalbumin present in muscle and in the relative expression of two parvalbumin isoforms. We have demonstrated previously that anterior slow-twitch or red myotomal muscle relaxes more rapidly than that from the posterior for both rainbow and brook trout. Further, younger rainbow trout parr have faster red muscle relaxation rates than older smolts. Here we report similar results for fast-twitch or white muscle. We quantified the parvalbumin expression in red and white muscle from different body positions of rainbow trout parr and smolts and for brook trout (Salvelinus fontinalis) adults. There was a significant shift in total parvalbumin content of muscle: the faster muscle from the anterior myotome contained greater amounts of parvalbumin. For brook trout, longitudinal variation in relaxation rate was also associated with shifts in the relative expression of the two parvalbumin isoforms. The faster muscle of parr contained more parvalbumin. Lastly, trout white muscle tended to have higher levels of parvalbumin and greater levels of the Parv2 (relative to Parv1) isoform as compared to red muscle. Parvalbumin expression correlated with muscle relaxation rate in trout, although there were species-specific differences in the importance of altering total parvalbumin content versus shifts in relative parvalbumin isoform expression. [Copyright &y& Elsevier]

Abstract: The present paper analyses predation patterns, of Percichthys trucha and salmonid fish upon Galaxias maculatus in five lakes of northern Patagonia with differing community and environmental characteristics. Tank experiments were performed to evaluate relative efficiency of native and exotic predators of G. maculatus under treatments with and without cover (aquatic vegetation). Important differences were found between predators with regards to distribution and consumption of G. maculatus. Salmonids are more efficient than P. trucha in consuming G. maculatus in deep environments with scarcely vegetation; in contrast to native species they frequently use the pelagic environment. Although pelagic habitat might have served in the past as a refuge from native predators in the past, G maculatus now experiences intense predation in the pelagic zone by exotic salmonids. It is suggested that the widespread distribution of G. maculatus in Patagonian lakes may have facilitated the success of salmonids throughout Patagonia. [Copyright &y& Elsevier]

Red or aerobic muscle from the anterior of rainbow trout Oncorhynchus mykiss activates (generates force) more quickly than that from the posterior. TnT is a component of the troponin complex that modulates muscle activation once Ca2+ is bound. Since trout express at least two forms of TnT in their red muscle (S1 and S2), the differential expression of these two forms was predicted to explain variations in contractile properties. TnT isoforms from trout muscle were identified through hydroxyapatite chromatography of purified myofibrillar proteins followed by SDS -PAGE. Western blots employing a mammalian anti-troponin T monoclonal antibody were used to identify TnT isoforms. The relative expression of the two isoforms of TnT was then examined at seven longitudinal positions from each of three fish using SDS- PAGE and densitometry on the silver-stained TnT bands. A significant shift in expression was detected from anterior to posterior in all three fish with TnT S1 becoming more dominant in the posterior red muscle. As predicted, a shift in TnT expression was associated with the decrease in activation rate along the length of the fish. This study was then extended to include a different species of salmonid, brook trout Salvelinus fontinalis, to explore the generality of TnT modulation of muscle activation. Muscle contractile properties were determined from anterior and posterior muscle, and relative expression of S1 and S2 was determined. Unlike rainbow trout, there is no consistent longitudinal pattern of muscle activation in brook trout: some fish have kinetically faster muscle in the anterior, some in the posterior. Similarly, there is no consistent pattern of TnT expression. Individual analysis of muscle activation and TnT expression in brook trout provides insight into the role of TnT in modulating muscle activation in slow fish muscle. [ABSTRACT FROM AUTHOR]

The article presents a study on the effect of climate change on southern Appalachian stream populations such as book and rainbow trout which are tracked for 30 years using a geographic information system database. The abundances of trout are found to increase due to the increased in temperature while the complexity of the changes in the abundances of trout in zones are associated with temperature and stream flow.