Effects of exercise, social facilitation, and delayed conditioning after vi exercise on the learning behavior of 5 to 6-inch rainbow trout, Salmo gairdneri, was measured in a conditioned avoidance response apparatus. The conditioning schedule contained an intertrial interval between alternate presentations of conditioned (light) and unconditioned (shock) stimuli. This randomization eliminated learning losses found in a previous study. Mean percentage avoidance, the measurement of learning, did not decrease significantly during conditioning trials. Exercised fish learned avoidance better than did non-exercised fish. Mean percentage avoidance for fish exercised at 0.5 ft/sec was 66.3; at 1.0 ft/ sec, 1.5 ft/sec, and no-exercise, mean percentage avoidance was 68.2, 68.9 and 65.0, respectively. Social facilitation affected learning in the one, two, and three fish per cell tests, where mean percentage avoidance was 55.5, 68.9, and 81.0 percent, respectively. A delay of 24 hours between exercise and conditioning resulted in decreased learning levels. Mean percentage avoidance was 60.3, 63.5, 67.7, and 53.7 for the 1-, 2-, 2-, and 24-hour delay tests, respectively; however, mean percentage avoidance for the last 60 trials of each test indicated the 1-, 2-, and 4-hour delay tests were all similar, over 70 percent, while mean percentage avoidance for the 24-hour delay test was only 57.8 percent.

Rainbow trout lactate dehydrogenase (LDH) B2' B2' , B2' B2" and B2" B2" phenotypes were tested under a variety of conditions for swimming endurance, oxygen consumption rates, and blood pH, p02, and lactate. The B2" B2" phenotype exhibited a lower swimming endurance, under a limited oxygen supply, than the B2' B2' and B2' B2" phenotypes. Blood pH at fatigue did not differ among the LOH phenotypes that swam under low oxygen conditions (2 mg/1). Blood p02 at fatigue was significantly higher for females than for males under low oxygen conditions. Oxygen consumption rates were significantly higher for males than for females at dissolved oxygen concentrations of 3 mg/1 to 8 mg/1. The depression in oxygen consumption rates at low oxygen levels was greater for males than for females. The increase in blood lactate with swimming under low oxygen concentrations and static exposure to low oxygen depended on LOH phenotype. The adaptive significance of the LDH B2' and B2" alleles was discussed. Thirteen populations of Intermountain cutthroat trout were sampled for biochemical genetic variation. Variation was observed in muscle aspartate aminotransferase for all populations which would fit a genetic model of two loci and three alleles. Unique muscle A group lactate dehydrogenase variation was observed in Snake Valley cutthroat trout which suggested the presence of several variant alleles. Allele frequencies for tetrazolium oxidase changed during three consecutive years in Bear Lake cutthroat trout that were trapped and spawned artificially. The possible causes of those changes were discussed. No variation was observed in alphaglycerophosphate dehydrogenase, isocitrate dehydrogenase, eye lactate dehydrogenase or muscle malate dehydrogenase in cutthroat trout.

Les substances poly- et per-fluorées (PFAS), exclusivement d’origine anthropique, sont de nos jours largement utilisées dans diverses applications industrielles et domestiques. La synthèse des PFAS engendre leurs rejets dans l’environnement, où ces composés se retrouvent aussi bien dans l’atmosphère que dans les milieux terrestres et aquatiques. Les études de distribution environnementale, relativement récentes, ont montré la bioaccumulation de certains PFAS chez les vertébrés aquatiques. La toxicocinétique (TK) des PFAS est particulière en raison de leurs propriétés physico-chimiques. Même si les études de TK de ces composés sont de plus en plus nombreuses, quelques verrous mécanistiques restent encore à lever chez les vertébrés aquatiques, notamment concernant les processus d’absorption, de distribution et d’élimination. Dans l’optique d’améliorer ces connaissances, un modèle toxicocinétique à base physiologique (PBTK) a été développé pour décrire le devenir de trois PFAS appartenant à la famille des perfluoroalkyles : le perfluorooctane sulfonate (PFOS), le perfluorohexane sulfonate (PFHxS) et l’acide perfluorononanoïque (PFNA). Ce modèle PBTK s’appuie sur les paramètres physiologiques de la truite arc-en-ciel (Oncorhynchus mykiss) et a permis de tester plusieurs hypothèses mécanistiques de la bioaccumulation des PFAS, utile à l’évaluation du risque engendré par l’exposition à ces substances. La croissance et la température de l’eau, facteurs clés dans la TK des poïkilothermes, ont également été intégrées dans le modèle. Les trois expériences d’exposition aux PFOS, PFHxS et PFNA par voie alimentaire à différentes températures (7°C, 11°C et 19°C) réalisées au cours de cette thèse ont permis (i) de mesurer les concentrations dans les organes d’intérêt et (ii) de calibrer et évaluer les prédictions du modèle / Poly- and per-fluorinated substances (PFAS), exclusively derived from anthropogenic activity, are nowadays widely used for industrial and domestic purposes. During their synthesis, PFAS are released in the atmosphere as well as in aquatic and terrestrial compartments. Environmental distribution studies are relatively recent and have shown the bioaccumulation of some PFAS in aquatic vertebrates. Physico-chemical properties of PFAS lead to a specific toxicokinetic (TK) profile. Although TK studies on these compounds are becoming more and more abundant, some mechanistic challenges still need to be solved for aquatic vertebrates, particularly for absorption, distribution and elimination processes. In order to improve this knowledge, a physiologically based toxicokinetic (PBTK) model has been developed to describe the fate of three PFAS belonging to the perfluoroalkyl family: perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) and perfluoronanoic acid (PFNA). This PBTK model was parametrized with rainbow trout (Oncorhynchus mykiss) physiological parameters. Next, it was used to test several mechanistic hypotheses about PFAS bioaccumulation, useful for improving the risk assessment of these chemicals. Fish growth and water temperature are key factors in the TK for poikilotherms. So, they have been integrated in the model. Three experiments of dietary exposure to PFOS, PFHxS and PFNA at different temperatures (7°C, 11°C and 19°C) have been performed. They allowed (i) to measure concentrations in organs of interest and (ii) to calibrate and evaluate the model predictions

The evolution and maintenance of multiple phenotypes within populations is an interesting evolutionary and ecological question, and is becoming increasingly important for the restoration and conservation of partially migratory species. In particular, why individuals adopt a particular phenotype has been the focus of numerous research efforts. In the partially migratory species Oncorhynchys mykiss (commonly known as steelhead and rainbow trout), I found that sex plays a strong role in whether an individual adopts an anadromous or resident life history. I observed a higher frequency of females adopting the anadromous tactic throughout the species range, and I attributed this to the relationship between body size and reproductive success in females that is not present in males. I did not observe differences in female bias along gradients of latitude or migration distance, and I hypothesize that while the frequency of tactics among populations may change along these gradients, either the change is equal between males and females, or an interaction of latitude and migration distance may control changes. I did not observe a corresponding male bias in the one resident population I sampled, and suggest that this is the result of a high frequency of residents in that population. I propose that sex ratios could be a valuable metric for measuring frequency of life-history tactics in populations and could facilitate the investigation into the controls of life-history tactics across broad scales. / Graduation date: 2013

Juvenile rainbow trout (Oncorhynchus mykiss) fed L-tryptophan (TRP) supplemented feed for 7 days show a suppression of aggressive behaviour along with a reduction in post-stress plasma cortisol levels. However, 3 days of elevated dietary TRP does not have any effects on either aggressive behaviour or post-stress plasma cortisol levels. The effects of TRP on aggression and stress responsiveness could be related to elevated brain serotonergic activity, TRP being the precursor of serotonin (5-HT). However, 5-HT is, in turn, the precursor of melatonin (ME) and we found that elevated dietary intake of TRP results in an increase in daytime plasma levels of ME. Elevated plasma ME concentrations in rainbow trout fed TRP supplemented feed appear to be of gastrointestinal origin. ME has been suggested to have inhibitory effects on aggressive behaviour and to act as a glucocorticoid antisecretagogue. However, we found that exogenuos ME did not affect aggressive behaviour or post-stress plasma cortisol in rainbow trout. Instead, the effects of TRP on aggressive behaviour and plasma cortisol were mimicked by treatment with the selective serotonin re-uptake inhibitor, citalopram, suggesting that the effects of TRP are mediated by a stimulation of brain 5-HT activity and not by increased ME synthesis and secretion. However, the slow time-course of the effects of TRP on aggressive behaviour and plasma cortisol suggests that effects on 5-HT receptors mechanism are likely to be involved.

A whole-cell DHA-rich algal product (A-DHA, provided by Evonik Industries) that is rich in DHA (125 mg DHA/g dry matter) is a possible replacement for fish oil in salmonid diets. The nutrient digestibilities of the algal product were measured in rainbow trout in freshwater and in Atlantic salmon in saltwater (32-33 ppm). In experiment 1, rainbow trout (initial weight ~ 300g) were randomly assigned to 12 x 120 L tanks (n = 10 per tank). A reference diet containing 1% Celite as an indigestible marker and three test diets with increasing percentage of A-DHA substitution (6.67%, 13.33% and 20%) were fed. Feces were collected using a settling column and feed and feces analyzed for digestible dry matter (DM), gross energy (GE), ash, crude protein (CP), essential amino acids and total lipid. The digestibility of six long-chain fatty acids including 18:1n-9 (OA), 18:2n-6 (LA), 18:3n-3 (ALA), 20:4n-6 (ARA), 20:5n-3 (EPA) and 22:6n-3 (DHA) was measured. In experiment 2, Atlantic salmon (~170g) were randomly distributed to 12 fiberglass tanks (600L) with 106 fish per tank. The fish were assigned to four diets with the same levels of A-DHA inclusion as for rainbow trout and yttrium oxide (Y2O3) was used as an inert marker. Feces were collected by stripping and the digestibilities of DM, CP and lipid as well as OA, LA, ALA, ARA, EPA and DHA were determined. In experiment 1, the apparent digestibility of dietary DM, GE and lipid in rainbow trout declined significantly with increasing inclusion of A-DHA (P < 0.01). The inclusion of A-DHA had no effect on the digestibility of CP and ash as well as the availability of essential amino acids (P > 0.05). Furthermore, increased inclusion of A-DHA resulted in significantly lower digestibility of ARA, EPA and DHA (P < 0.05). A similar pattern was seen in the digestibility of OA, LA and ALA, although the effect of A-DHA inclusion was not statistically significant. Regression analysis revealed that nutrient contribution from A-DHA had significantly negative linear and quadratic effects on the apparent digestibility of DM, GE, and lipid. The inclusion levels of A-DHA had both significantly negative linear and quadratic effects on digestibility of LA and ALA, whereas only significantly negative linear effect was found on OA. Significantly negative linear and quadratic regressions were observed for the digestibility of ARA, EPA and DHA. The linear regression for CP was significantly negative and the regressions for the individual amino acids were not significant (P > 0.05). In experiment 2, dietary inclusion of A-DHA had a significantly negative effect on lipid digestibility in Atlantic salmon, at all inclusion rates whereas the significant negative effect on digestibilities of DM and CP was only observed in fish fed 20% A-DHA. The digestibilities of OA, LA, ALA and EPA were greater than 91%. In contrast, the apparent digestibilities of ARA and DHA decreased significantly with increasing substitution of A-DHA (P < 0.01). Significantly negative linear and quadratic regressions were found between nutrient contribution from A-DHA to the diets and apparent digestibility of DM, CP and lipid, so were LA, EPA and DHA. However, there were only significant quadratic regressions for OA, ALA and ARA, but not significant linear effects. Subsequently, a twelve-week feeding trial in rainbow trout was conducted to investigate the impact of replacing fish oil with A-DHA in canola-oil-based diets on the growth performance and fatty acid composition and retention. Four experimental diets containing only canola oil (CO; 13.5%), fish oil (FO; 13.5%), canola oil and fish oil (C+F; 7.4% and 6.1%, respectively) or canola oil and A-DHA (C+A; 15.5% and 6%, respectively) were formulated to contain 386.2 g/kg digestible crude protein and 17.58 MJ/kg digestible energy. In addition, the C+A diet was formulated to have the same DHA concentration as in the C+F diet. Each diet was fed to three tanks of rainbow trout (average initial weight of 70g; n = 17/tank) and the fish were fed to apparent satiation 2 times daily. At the end of the growth trial, all fish approximately tripled their weight. No significant differences were noted between the dietary treatments in growth performance as measured by final weight, average weight gain, feed intake, specific growth rate (SGR) and feed conversion ratio (FCR). Although FO and C+A fed fish tended to accumulate more lipids, final whole body lipid content did not differ significantly between dietary treatments (P = 0.11). The concentrations of EPA, DHA as well as total n-3 fatty acid were significantly higher in fish fed the FO diet than fish fed the other 3 diets. The C+A fed fish had lower EPA and higher DHA concentrations compared with the CO and C+F fed fish; however, the differences were not significant. Apparent retention of total lipid in the trout was not significantly influenced by treatments (P > 0.05). Similarly, dietary treatments had no significant effect on the apparent retention of total saturated fatty acids, total mono-unsaturated fatty acids, n-3 polyunsaturated fatty acids and n-6 polyunsaturated fatty acids. The retention of 18:4n-3 (SDA) was significantly higher (> 100%) in fish fed CO and C+A compared with fish fed FO and C+F (< 51%), indicating greater bioconversion of ALA to SDA in the CO and C+A fed fish than in FO and C+F fed fish. The retention of EPA in the CO and C+A fed fish was over 100%, suggesting a net synthesis of EPA in these treatment groups. In contrast, the EPA retention in the FO and C+F fed fish was 55 and 21%, respectively, which showed a tendency to be significantly lower than that in the other two groups (P = 0.09). The CO fed fish had significantly higher DHA retention than fish fed the other 3 diets. The DHA retention in the FO fed fish (112%) was numerically but not significantly higher than in the C+F (66%) and C+A fed fish (73%). Thus, feeding the C+A to rainbow trout resulted in DHA retention equal to feeding the C+F.

A series of experiments with Aeromonas salmonicida and infectious hematopoietic necrosis virus (IHNV) were carried out to determine dynamics of the spread of infection in chinook salmon (1.2-1.98g) and rainbow trout (1.2-3.1g). It was found in experiments with A. salmonicida that fish infected by bath immersion became infectious at 4 days postexposure (dpe), one day prior to dying from furunculosis. In cohabitation experiments with a single infected fish donor, an average of 75% disease specific mortality was obtained. There was suggestive evidence that there is a positive relationship between holding volumes and furunculosis prevalence in cohabitation experiments with single donor fish. Median day to infection was inversely correlated with density. The threshold density at density of 1.97 fish/L was approximately 30 times less than the density of 0.08 fish/L, 13.33 and 320 fish respectively. Reproductive ratio (R₀) and transmission coefficient (β) in the furunculosis epizootic were 3.23 and 0.021 (individuals*day)⁻¹ respectively. The mortality rate (α) of infected animals was 28.7% per day. The models constructed successfully mirrored the results of laboratory experiments. Data produced by simulation of the models were significantly associated with the data obtained from laboratory experiments for susceptible (S) class and also for infected class. In similar experiments carried out with IHNV, it was found that donor fish became infectious 3 dpe. The virus levels in donor fish and prevalence levels were also highly associated. Smaller volumes of that led to higher prevalence levels than observed in bigger volumes with 60 or 30 fish in each. A single donor fish was able to transfer virus to recipient fish. However, unlike the A. salmonicida experiment, transmission was insufficient to initiate a full-scale infectious hematopoietic (IHN) epizootic. Estimated parameters for dynamics of infection were approximately half of the values for A. salmonicida (R₀=2.57,β=0.008 (individuals*day)⁻¹ and α=0.15). The models constructed for IHNV spread were used to simulate the results of density experiment. However, it was not possible to test the association between susceptible and infected classes due to inadequate number of infected fish. / Graduation date: 2001

High-resolution velocity measurements were undertaken over a series of redds and riffles on a gravel-bed stream to quantify the hydrodynamics preferred by spawning brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) for redd-site selection. On each riffle studied, over 6,000 velocity measurements per day were acquired to quantify the velocity, depth, Reynolds number, Froude number, bed shear, and turbulent kinetic energy per unit area of streambed in attempts to relate fluid properties to redd-site selection, relative to remaining riffle structures. Results showed that velocity, Reynolds number, and Froude number vary widely at the redd- and riffle-scale with no apparent correlation to spawning location preference. Turbulent kinetic energy per unit area consistently demonstrated a strong correlation with redd locations whereby the metric maintained low values (i.e., unidirectional flow with little turbulence) where redds and attempted redds were observed. Habitat suitability indices were applied at the reach-, riffle-, and redd-scale using the results of the high-resolution velocity measurements. Findings demonstrated that habitat suitability indices, which are based on reach-scale hydraulics, were adequately represented at the reach scale. However, by decreasing the scale to the riffle- or redd-scale, where increasing heterogeneity in the flow regime is revealed, habitat suitability indices failed to adequately reflect the habitat conditions preferred by the spawning fish.

High-resolution velocity measurements were undertaken over a series of redds and riffles on a gravel-bed stream to quantify the hydrodynamics preferred by spawning brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) for redd-site selection. On each riffle studied, over 6,000 velocity measurements per day were acquired to quantify the velocity, depth, Reynolds number, Froude number, bed shear, and turbulent kinetic energy per unit area of streambed in attempts to relate fluid properties to redd-site selection, relative to remaining riffle structures. Results showed that velocity, Reynolds number, and Froude number vary widely at the redd- and riffle-scale with no apparent correlation to spawning location preference. Turbulent kinetic energy per unit area consistently demonstrated a strong correlation with redd locations whereby the metric maintained low values (i.e., unidirectional flow with little turbulence) where redds and attempted redds were observed. Habitat suitability indices were applied at the reach-, riffle-, and redd-scale using the results of the high-resolution velocity measurements. Findings demonstrated that habitat suitability indices, which are based on reach-scale hydraulics, were adequately represented at the reach scale. However, by decreasing the scale to the riffle- or redd-scale, where increasing heterogeneity in the flow regime is revealed, habitat suitability indices failed to adequately reflect the habitat conditions preferred by the spawning fish.

Cell-cycle checkpoint proteins help maintain genomic integrity by sensing damaged DNA and initiating DNA repair or apoptosis. Checkpoint protein activation to cell-cycle damaging agents can involve post-translational modifications and these alterations provide a means to determine whether DNA in a cell is damaged or not. Steinmoeller et al. (2009) showed that checkpoint proteins are suitable biomarkers for detecting genotoxins in Oncorhynchus mykiss (rainbow trout). In this project, two evolutionarily conserved checkpoint proteins, Rad1 and Hus1, have been cloned from rainbow trout and antibodies against these proteins were developed. This is the first time that either Rad1 or Hus1 has been characterized in rainbow trout. For rtRad1, it was determined that the open-reading frame was 840bp, which encodes 279aa with a predicted protein size of 31kDa. The rtRad1 amino-acid sequence is highly conserved and contains conserved exonuclease and leucine zipper domains. RT-PCR was used to identify alternatively spliced variants of rtRad1 and it appears that these variants encode different sized Rad1 proteins that are tissue and cell-line specific. A Rad1 splice variant that encodes an 18kDa protein appears to be abundant only in heart tissue and in the RTgill-W1 and RTbrain-W1 cell-lines. A genotoxicity study was completed where RTgill-W1 and RTbrain-W1 cells were treated with bleomycin, which induces double-stranded DNA breaks. In RTgill-W1, levels of an 18kDa Rad1 protein increased in a dose-dependent manner while in RTbrain-W1 the Rad1 levels remained the same. It appears that this 18kDa Rad1 protein may be directly involved in maintaining genomic integrity and shows potential to be used as a genotoxicity biomarker. This is the first time that an isoform of Rad1 has shown to be modified in the presence of a damaging agent. Both Rad1 and Hus1 need to be further characterized to determine their usefulness as genotoxicity biomarkers.