Wild Trout Research Articles

Choice experiment assessment of anglers’ salmonid conservation preferences

Wild Atlantic salmon and sea trout are in danger in several fisheries of the northern hemisphere due to anthropic activities. The pressures on fish stocks include excessive commercial and recreational harvests, as well as habitat depletion. In this paper, we present a choice experiment assessment of recreational anglers’ preferences for conservation options, aiming to reduce harvest and improve ecosystem quality of salmon fisheries using Ireland as a case study. Data were collected by online survey and analysed with a latent class logit model. Results indicate two groups of anglers with diverging opinions and preferences on salmon conservation priorities, which will likely be reflected in different levels of acceptance of conservation initiatives.

Growth, Condition, and Trophic Relations of Stocked Trout in Southern Appalachian Mountain Streams

AbstractStream trout fisheries are among the most popular and valuable in the United States, but many are dependent on hatcheries to sustain fishing and harvest. Thus, understanding the ecology of hatchery‐reared trout stocked in natural environments is fundamental to management. We evaluated the growth, condition, and trophic relations of Brook Trout Salvelinus fontinalis, Brown Trout Salmo trutta, and Rainbow Trout Oncorhynchus mykiss that were stocked in southern Appalachian Mountain streams in western North Carolina. Stocked and wild (naturalized) trout were sampled over time (monthly; September 2012–June 2013) to compare condition and diet composition and to evaluate temporal dynamics of trophic position with stable isotope analysis. Relative weights (Wr) of stocked trout were inversely associated with their stream residence time but were consistently higher than those of wild trout. Weight loss of harvested stocked trout was similar among species and sizes, but fish stocked earlier lost more weight. Overall, 40% of 141 stomachs from stocked trout were empty compared to 15% of wild trout stomachs (N = 26). We identified a much higher rate of piscivory in wild trout (18 times that of stocked trout), and wild trout were 4.3 times more likely to consume gastropods relative to stocked trout. Hatchery‐reared trout were isotopically similar to co‐occurring wild fish for both δ13C and δ15N values but were less variable than wild trout. Differences in sulfur isotope ratios (δ34S) between wild and hatchery‐reared trout indicated that the diets of wild fish were enriched in δ34S relative to the diets of hatchery‐reared fish. Although hatchery‐reared trout consumed prey items similar to those of wild fish, differences in consumption or behavior (e.g., reduced feeding) may have resulted in lower condition and negative growth. These findings provide critical insight on the trophic dynamics of stocked trout and may assist in developing and enhancing stream trout fisheries.

First Report of Cryptosporidium Molnari-Like Genotype and Cryptosporidium parvum Zoonotic Subtypes (IIaA15G2R1 And IIaA18G3R1) in Brown Trout (Salmo trutta)

This study reports for the first time the molecular characterization of Cryptosporidium spp. in Salmo trutta. A total number of 613 brown trout was captured by local anglers in 44 Galician rivers within 10 river basins (NW Spain) during the 2015 fishing season (March-August) and classified into groups according to their size. The gastrointestinal tracts were dissected and differentiated in pyloric ceca and intestine, which were homogenized and concentrated in phosphate-buffered saline 0.04 M pH 7.2/diethyl ether (2:1). Cryptosporidium oocysts were observed by immunofluorescence microscopy in 103 of 613 specimens (16.8%), with a mean intensity of 326.7 oocysts/trout. The highest prevalence rate was detected in specimens <2 yr (23.1%). Considering the anatomical location, Cryptosporidium oocysts were observed in pyloric ceca (72 trout, 69.9%), intestine (15 trout, 14.6%), or in both locations (16 trout, 15.5%), showing statistically significant differences between the 2 locations ( P < 0.01). The prevalence rate in the pyloric ceca increased with the age/size of the fish (62.2% vs. 70.8% vs. 83.3% for trout <2, 2-3, and >3 yr, respectively). By contrast, the prevalence rate in the intestinal location decreased with the age/size of specimens (21.6% vs. 12.5% vs. 7.7% for trout <2, 2-3, and >3 yr, respectively), but statistically significant differences were not determined. The microscopic observation of clusters of 4-20 oocysts in the pyloric ceca from 5 specimens of 20-28-cm body length is remarkable. By polymerase chain reaction amplification and sequencing of fragments of small-subunit ribosomal DNA ( SSU-rDNA), GP60, hsp70, and actin loci, Cryptosporidium molnari-like genotype was identified in 1 trout and Cryptosporidium parvum (subtypes IIaA15G2R1 and IIaA18G3R1) in 47 fish, including those specimens in which oocyst clusters were observed. This finding may indicate a true infection by C. parvum, as the homogenization process would break the epithelial cells, releasing oocysts, free or in clusters. Cryptosporidium oocysts were detected in wild trout captured from 27 of 44 rivers sampled in Galicia (61.4%), belonging to 9 of the 10 river basins considered, confirming the presence of this protozoan parasite in Galician rivers and proving their wide dispersion in aquatic freshwater environments. The identification of the zoonotic species C. parvum in brown trout may indicate a risk to public health as trout may be a potential source of infection to humans. Thus, edible wild fish extend the range of foodstuffs involved in the transmission of cryptosporidiosis.

Exploring the Brine Microbiota of a Traditional Norwegian Fermented Fish Product (Rakfisk) from Six Different Producers during Two Consecutive Seasonal Productions.

The purpose of this study was to explore the microbiota of Norwegian fermented fish (rakfisk), a traditional product popular in the Norwegian market. Brine samples, collected from six producers during two subsequent years, were used. The producers applied different salt concentrations (between 3.8% and 7.2% NaCl), ripening temperatures (between 3.5 and 7.5 °C), fish species (trout or char), and fish upbringing (wild trout, on-shore farmed trout or char, and off-shore farmed char). The microbiota in the brine during the ripening process was mainly characterized by DNA-based, culture-independent methods. In total, 1710 samples were processed and of these 1342 were used for the final analysis. The microbiota was dominated by Gammaproteobacteria and Bacilli with the largest variance between samples associated with the genera Psychrobacter and Lactobacillus. The variance in the material was mainly determined by the origin of the samples, i.e., the different producers. The microbiota from the individual producers was to a large extent reproducible from one year to the next and appeared to be determined by the relatively small differences in the salinity and the ripening temperature. This is the first study exploring the microbiota in rakfisk brine and it provides insights into environmental factors affecting the rakfisk ecosystems.

Evaluating the potential for sea lice to evolve freshwater tolerance as a consequence of freshwater treatments in salmon aquaculture

Increasing usage of non-medicinal methods (NMMs) to control sea louse infestations on salmon farms has raised questions about whether sea lice may be able to evolve tolerance of NMMs. Of particular concern is the potential for sea lice to evolve freshwater tolerance as a result of freshwater treatments. Wild trout and some juvenile salmonids swim into freshwater to control infestations and regain ionic balance after disruption by sea lice; freshwater tolerance would compromise this potentially adaptive behavior. Here we evaluated the potential for freshwater tolerance to evolve in the sea louse Lepeophtheirus salmonis. When exposed to low-salinity water, parasitic stages of sea lice are able to osmoregulate through the host, while larval planktonic stages are not. Transcriptomic work suggests that sea lice mount a costly polygenic stress response when exposed to brackish water. The population structure of sea lice is panmictic in both the Pacific and Atlantic, making it conducive to rapid evolutionary responses. It is unknown how much heritable genetic variation these panmictic populations have for freshwater treatments. While usage of freshwater treatments on wellboats is increasing, it is unclear whether the freshwater itself is a strong selective force; during the freshwater exposure, sea lice can die from physical disruption during pumping and filtration on the wellboat. Future studies are advised to quantify the heritable variation in freshwater tolerance in sea louse populations, characterize mechanisms for freshwater tolerance in planktonic and attached sea lice, and assess the risk of freshwater tolerance evolution under different management strategies.

Morphological survey as powerful detection tool of pure and local phenotypes inSalmo truttacomplex

The native Mediterranean trout populations in central Italy are at risk of extinction. Hybridization with the alien Atlantic trout represents one of the major threats to the species. The main aim of the research was to test the efficiency of morphological characterization in revealing alien trout introduction, pure lineages and local adaptations, in five watersheds of central Apennines (Italy). Data analysis was carried out for a total of 258 specimens already genetically identified. The results of the multivariate analysis, performed using 10 qualitative and 47 quantitative variables, revealed two distinct phenotypic groups and confirmed, at a morphological level, the genetic separation between Atlantic and Mediterranean trout. The morphological variables that play a key role in the discrimination of the Mediterranean trout were: (i) number of parr marks with striped pattern, (ii) adipose fin mainly with white color and without black spots, and (iii) number of black opercular spots, compared to the Atlantic trout. The geometric analysis revealed the importance of the spatial arrangements of spots on the fish flank and the shape of caudal peduncle in discriminating different Mediterranean populations. The information collected confirmed the powerful of morphological surveys in the screening of conservation status of wild trout populations.

Specialization and Characterization of Stocked‐Trout Anglers in Virginia, USA

AbstractTo manage a recreational fishery effectively, agencies must understand who actively utilizes the fishery. Despite the popularity of stocked‐trout fishing, most studies have focused on fishing for wild trout, while few studies have attempted to describe stocked‐trout anglers. We sought to characterize stocked‐trout anglers specifically. We interviewed 3,367 anglers during their fishing trips on 17 stocked‐trout waters across Virginia. We asked anglers questions relating to their demographics, motivations, fishing and management preferences, catch and harvest that day, level of specialization, and level of satisfaction. Using a hierarchical clustering method, we identified four unique clusters of anglers: specialists, avid anglers, consumptive‐experienced anglers, and casual anglers. The clusters differed in their motivations for fishing, management and fishing preferences, and level of satisfaction. Proportions of each cluster varied across fishery types. Results from this study depict how stocked‐trout anglers differ from wild‐trout anglers. These results can help managers to adjust management strategies for various angler groups and can help managers to focus their efforts on how to recruit and retain anglers.

Ecology and conservation of the Mediterranean trout in the central Apennines (Italy)

The Mediterranean brown trout (Salmo trutta complex) is one of the freshwater fish species complex at greater risk of extinction in the Mediterranean area. The introduction of alien invasive species and their interaction with the native fauna represent some of the major threats to the survival of this species. Currently, the genetic variability of the Mediterranean trout (Salmo trutta complex) is being compromised by the introgressive hybridization with the Atlantic trout (Salmo trutta Linnaeus, 1758). Therefore, it is necessary to gain further knowledge on genetic and demographic characteristics of Mediterranean trout populations, that, combined with environmental and angling data, will allow to undertake sound conservation strategies. The aims of the present study were to analyze: i) the demographic characteristics of the Mediterranean trout in seven central Apennine river basins where native populations are threatened by stocking with the domestic trout of north Atlantic origin; ii) the influence of both environmental parameters and different fishery management strategies on the status of native trout populations. The project focuses on 14 sites included in the Natura 2000 EU wide network of nature protection areas, established under the 1992 Habitat Directive. A total of 25 watercourses were investigated for a total of 32 sampling sites. A census of the fish fauna was carried out by electrofishing at each sampling location. Fish and environmental data were collected in spring and autumn 2014. The results obtained in the present research allowed us to detect the presence of three residual Mediterranean trout populations with a high degree of genetic integrity in the study area. The native trout populations were characterized by higher abundances and higher adult density values. Well-structured native populations with higher legal-size specimens density and poor body conditions in terms of relative weight were observed in the no-fishing areas, probably due to the presence of intraspecific competition phenomena. The environmental analysis confirmed the key role played by the geological characteristics of the central Apennines in shaping the introgression levels observed in the wild trout populations, while the recovery of the water quality appears decisive in the development of management strategies aimed at their conservation.

Body composition and sensory quality of wild and farmed brown-trout (Salmo trutta) and of farmed rainbow-trout (Oncorhynchus mykiss)

ABSTRACT: Body composition (total crude protein, lipid, ash, dry matter and moisture) and fatty acid profiles were compared between wild and farmed brown trout and between farmed rainbow trout. Farmed brown trout contained the highest amount of crude protein (18.39%), whereas farmed rainbow trout contained higher levels of crude lipid (2.35%). Thirty six fatty acids were found, including sixteen saturated fatty acids (SFA), nine monounsaturated fatty acids (MUFA) and eleven polyunsaturated fatty acids (PUFA). The most abundant SFA in all fish were palmitic acid and stearic acid. However, the most abundant fatty acids in all trout samples were MUFA and PUFA. MUFA were the most abundant fatty acid in farmed brown trout because of high abundance of oleic acid in this samples (35.46g / 100g fatty acids). PUFA were predominating in the samples of wild brown trout and of rainbow trout 56.16 and 56.29g/100g fatty acids, respectively). Linoleic acid was the most abundant fatty acid reported in the rainbow trout (47.17g/100g fatty acids). Significantly higher amounts of docosahexaenoic acid, α-linolenic acid, arachidonic acid and eicosapentaenoic acid were observed in the wild trout samples. Wild brown trout contained significantly more docosahexaenoic acid, α-linolenic acid, Eicosapentaenoic acidArachidonic acid. Sensory quality evaluation, by a consumers’ panel, revealed all samples were equally well accepted.

Change of foraging behavior of cormorants and the effect on river fish

Since the European population of great cormorants (Phalacrocorax carbo sinensis) rapidly increased 30 years ago, Denmark has been one of the core breeding areas for this colonial water bird. Following a 10-year period with stable breeding numbers in Denmark, the population of great cormorants decreased. At the same time, a combination of cold winters and low availability of coastal prey fish apparently triggered birds to seek new foraging areas. Thus, cormorants began to appear in rivers and streams coinciding with an observed massive decline of fish, mainly brown trout (Salmo trutta) and grayling (Thymallus thymallus). In this paper, we present the results from studies using radio-telemetry, PIT-tagging, and traditional fish surveys to estimate the impact of predation in Danish lowland rivers. Recovery of PIT-tags revealed that an estimated 30% of wild trout and 72% of wild grayling tagged in a small river were eaten by cormorants. In another medium-sized river, 79% of radio-tagged adult grayling were removed, presumably by cormorants during winter. Thus, predation from cormorants appears to be at a level that explains the observed collapse of grayling and brown trout populations in many Danish streams.

The demand for angling licenses: A case study from Taupo, New Zealand

Lake Taupo is managed as a wild trout fishery funded entirely by the sale of angling licenses. Since 1986 license sales have more than halved and this study aimed to identify the factors driving this trend. We used an economic demand theory framework in which to estimate least squares multiple regression models of license sales for the 45-year period 1970/71–2014/15. Using first-differenced data to avoid multicollinearity, we found that the sale of each license type (i.e., adult day, week, month and season, and child day and season) was influenced by its own price and the prices of substitutes, together with a variable to measure the overall interest in Taupo angling – the total license sales to population ratio. In a separate model, we found that this ratio was primarily influenced by various measures of the quality of the fishing, together with the unemployment rate. Other variables used widely in the literature to explain declining angling participation, such as development, income, urbanisation, changing leisure interests, and demographic changes, were not statistically significant. We discuss the implications of our results for the management of the fishery.

CYPS MOLECULAR BIOMARKERS IN RAINBOW TROUT Oncorhynchus mykiss TO ASSESS OIL CONTAMINATION IN A PATAGONIAN STREAM

Cytochrome P450 (CYP) gene expressions were studied by semi-quantitative polymerase chain reaction (PCR) to assess oil pollution using liver and gills of juvenile rainbow trout Oncorhynchus mykiss sampled from La Mina stream (Bariloche, Argentina), up and downstream of a discharge of petroleum spill from an unproductive wellbore. Data was complemented with laboratory exposure to water accommodated fraction (WAF) from the oil spill. Oil exposure induced gill and liver CYP1A transcription (1.2-1.4-fold), which was used as reference biomarker. In both organs, CYP2K1 transcript was induced after 5 % WAF exposure, 24 h (1.8-2.0-fold), and it was down-regulated in more extended time (1.2-1.5-fold). CYP2M1 transcript levels were down-regulated in liver of impacted wild trout and in trout exposed to 5 % WAF during 96 h (1.5-1.7-fold). CYP2K1 and CYP2M1 are involved in the metabolism of fatty acids and estrogenic hormones, and its down-regulation would indicate metabolic alterations. CYP3A27 levels were only induced in liver of wild trout (1.6-fold), possibly related to crosstalk between aryl hydrocarbon receptor and pregnane X receptor signaling pathway. While CYP1A mRNA expression appears to be a more robust biomarker for detecting the effects of crude oil under different dose and exposure time, the expression of CYP2K1, CYP2M1 and CYP3A27 mRNAs would indicate different time exposure to oil pollution, particularly under high oil concentration in water. Hence, patterns of multiple CYP genes expression in rainbow trout gills and liver could be especially valuable for monitoring programs of crude oil pollution and remediation actions on Patagonian freshwater ecosystems.

Transfer of marine mercury to mountain lakes

Stocking is a worldwide activity on geographical and historical scales. The rate of non-native fish introductions have more than doubled over the last decades yet the effect on natural ecosystems, in the scope of biologically mediated transport and biomagnification of Hg and Hg-isotopes, is unknown. Using geochemistry (THg) and stable isotopes (N, Sr and Hg), we evaluate natal origin and trophic position of brown trout (Salmo trutta fario), as well as mercury biomagnification trends and potential pollution sources to three high-altitude lakes. Farmed trout show Hg-isotope signatures similar to marine biota whereas wild trout shows Hg-isotope signatures typical of fresh water lakes. Stocked trout initially show Hg-isotope signatures similar to marine biota. As the stocked trout age and shifts diet to a higher trophic level, THg concentrations increase and the marine Hg isotope signatures, induced via farm fish feed, shift to locally produced MeHg with lower δ202Hg and higher Δ199Hg. We conclude that stocking acts a humanly induced biovector that transfers marine Hg to freshwater ecosystems, which is seen in the Hg-isotopic signature up to five years after stocking events occurred. This points to the need of further investigations of the role of stocking in MeHg exposure to freshwater ecosystems.

A reassessment of the carnivorous status of salmonids: Hepatic glucokinase is expressed in wild fish in Kerguelen Islands

Salmonids belong to a high trophic level and are thus considered as strictly carnivorous species, metabolically adapted for high catabolism of proteins and low utilisation of dietary carbohydrates. However they conserved a “mammalian-type” nutritional regulation of glucokinase encoding gene and its enzymatic activity by dietary carbohydrates which remains puzzling regarding their dietary regime. The present study investigates the hypothesis that this conservation could be linked to a real consumption by trout of this nutrient in their natural habitat. To do so, brown trout were sampled in the sub-Antarctic Kerguelen Islands, a site presenting oligotrophic hydrosystems and no local freshwater fish fauna prior the introduction of salmonids fifty years ago. Qualitative and quantitative analysis of carbohydrate content within Kerguelen trout stomachs demonstrate that these animals are fed on food resources containing digestible carbohydrates. Additionally, glycaemia and more particularly gck mRNA level and gck enzymatic activity prove that Kerguelen trout digest and metabolise dietary carbohydrates. Physiological and molecular analyses performed in the present study thus strongly evidence for consumption of dietary carbohydrates by wild trout in natural environments. Investigating differences between Kerguelen individuals, we found that smaller individuals presented higher glycaemia, as well as higher carbohydrates contents in stomach. However no relationship between scaled mass index and any physiological indicator was found. Thus it appears that Kerguelen trout do not turn to carbohydrate diet because of a different condition index, or that the consumption of carbohydrates does not lead to a generally degraded physiological status.As a conclusion, our findings may explain the evolutionary conservation of a “mammalian-type” nutritional regulation of gck by dietary carbohydrates in these carnivorous fish.

Quantitative Genetic Variation in, and Environmental Effects on, Pathogen Resistance and Temperature-Dependent Disease Severity in a Wild Trout.

Health after pathogen contact varies among individuals because of differences in pathogen load (which is limited by resistance) and disease severity in response to pathogen load (which is limited by tolerance). To understand pathogen-induced host evolution, it is critical to know not only the relative contributions of nongenetic and genetic variation to resistance and tolerance but also how they change environmentally. We quantified nongenetic and genetic variation in parasite load and the associated temperature-dependent disease among trout siblings from two rivers. We detected a genetic variance for parasite load 6.6 times as large in the colder river. By contrast, genetic variance for disease traits tended to be larger in the warmer river, where the disease was manifested more severely. The relationships between disease severity and pathogen load (tolerance) exhibited plateaus at low pathogen load and stronger steepening slopes at high pathogen load in the warmer river. Our study demonstrates the environmental influence on disease severity, nongenetic and genetic variance for health-damage-limiting host abilities, and the shape of tolerance curves. Environmental variability is predicted to govern the presence and intensity of selection, change the relative contributions of nongenetic and genetic variance, and therefore hamper evolution toward more resistant and tolerant hosts.

Phenotypic convergence of artificially reared and wild trout is mediated by shape plasticity.

Phenotypic plasticity can be viewed as the first level of defense of organism homeostasis against environmental stress and therefore represents the potential to deal with rapid environmental changes. Transitions between low complexity, artificial environments and complex, natural habitats can promote phenotypic plasticity. Here, we conducted an experimental introduction with juvenile brown trout to evaluate the plasticity of shape in response to a transition between contrasting environments. We released 202 juvenile trout reared under hatchery conditions in a natural stream and analyzed changes in shape and morphological variability after 5 months. A geometric morphometrics approach based on 14 landmarks was used to compare changes in body shape for 37 fish recaptured at the end of the experiment. A similar number of hatchery and wild fish caught at the receptor stream were used as controls for shape in the two environments. After 5‐months, fish showed significant change in shape, shifting from elongated to robust shapes, and affecting to the relative position of the caudal peduncle. These new shapes were closer to wild than to the hatchery shapes, suggesting a process of rapid phenotype change. Moreover, these changes were concomitant with a marked increase in morphological variability. Our results support the hypothesis that phenotypic plasticity is a major potential for adjustment to environmental change but not the idea that shape can be constrained by initial shapes. We confirmed the “increased” variance hypothesis and phenotype convergence with wild morphs. This has important implications because stresses the role of phenotypic plasticity as a buffer that allows organisms to cope with important environmental discontinuities at time scales that preclude the onset of adaptive adjustments. We suggest that environmental conditioning and shape plasticity can overcome both reduced morphological diversity and phenotype uncoupling with habitat characteristics resulting from initial rearing in low complexity artificial environments.

Effect of chronic arsenic exposure under environmental conditions on bioaccumulation, oxidative stress, and antioxidant enzymatic defenses in wild trout Salmo trutta (Pisces, Teleostei).

The present study evaluates the relation between chronic arsenic (As) exposure in the natural distribution area of wild brown trout (Salmo trutta), oxidative stress and antioxidant enzymatic defenses. Two rivers of the same watershed were evaluated to highlight the correlation between As accumulation and the resulting stress: (i) the Presa River, which has high chronic As levels (2281.66 µg/L) due to past mining activity, and (ii) the Bravona River (control river). This metalloid was measured in main fish tissues (gills, kidney, liver, muscle, gonads and fins) and water. As organotropism in S. trutta was kidney > liver > gill > fin > gonad > muscle. The HepatoSomatic Index (HSI) and somatic condition (CF) were used to compare fish population conditions from both sites. Arsenic can be absorbed by the gills and can induce oxidative stress and disturb antioxidant defenses. The aim of this study was to evaluate oxidative stress response by measuring malondialdehyde (MDA) content, as a marker of lipid peroxidation, and antioxidant enzymatic defenses (Superoxide dismutase (SOD), catalase CAT, glutathione peroxidase (GPx) and glutathione S-transferase (GST)), in the main tissues of control and exposed trout. The highest MDA content was found in the kidney and liver of exposed trout. SOD and CAT activities in exposed livers and kidneys were considerably increased while a significant rise of GPx activity was observed only in the liver. GST activity was found to be significantly induced in the liver of exposed trout. The results demonstrate that arsenic bioaccumulation can induce lipid peroxidation and substantial modifications in antioxidant enzymatic defenses in main wild trout tissues.

Estimating thermal performance curves from repeated field observations.

Estimating thermal performance of organisms is critical for understanding population distributions and dynamics and predicting responses to climate change. Typically, performance curves are estimated using laboratory studies to isolate temperature effects, but other abiotic and biotic factors influence temperature-performance relationships in nature reducing these models' predictive ability. We present a model for estimating thermal performance curves from repeated field observations that includes environmental and individual variation. We fit the model in a Bayesian framework using MCMC sampling, which allowed for estimation of unobserved latent growth while propagating uncertainty. Fitting the model to simulated data varying in sampling design and parameter values demonstrated that the parameter estimates were accurate, precise, and unbiased. Fitting the model to individual growth data from wild trout revealed high out-of-sample predictive ability relative to laboratory-derived models, which produced more biased predictions for field performance. The field-based estimates of thermal maxima were lower than those based on laboratory studies. Under warming temperature scenarios, field-derived performance models predicted stronger declines in body size than laboratory-derived models, suggesting that laboratory-based models may underestimate climate change effects. The presented model estimates true, realized field performance, avoiding assumptions required for applying laboratory-based models to field performance, which should improve estimates of performance under climate change and advance thermal ecology.

Science, Politics, and Wild Trout Management at the 12th International Wild Trout Symposium

Science, Politics, and Wild Trout Management at the 12th International Wild Trout Symposium

Study of genetic diversity of wild Caspian trout Salmo trutta caspius in the Sardabrud and Astara Rivers, using D- Loop region sequencing

Study of genetic diversity of wild Caspian trout Salmo trutta caspius in the Sardabrud and Astara Rivers, using D- Loop region sequencing