La truite arc-en-ciel a un déterminisme du sexe strictement génétique de type XX/XY. Pourtant des femelles génétiques se sont spontanément masculinisées après une gynogénèse endomitotique. Ce phénotype masculinisé à pénétrance incomplète serait dû à une mutation inconnue appelée " mal ". Afin d'identifier le gène causal porteur de cette mutation, une meilleure caractérisation de son phénotype est nécessaire. Pour cela, nous avons procédé à la caractérisation du phénotype gonadique en utilisant à la fois des approches histologiques et moléculaires. Tous les animaux XXmal présentent une différenciation sexuelle très perturbée autant sur le plan histologique que sur le plan de leurs profils d'expression géniques. Parmi ces perturbations, l'inhibition de l'expression du gène de l'aromatase gonadique (cyp19a1a), une enzyme de synthèse des œstrogènes, pourrait être un facteur explicatif de cette masculinisation. De plus des températures d'élevage élevées (18°C) augmentent fortement la masculinisation de ces animaux XXmal. Enfin, la croissance des animaux XXmal est affectée négativement selon le degré de perturbation. En conséquence, la masculinisation de ces animaux serait le résultat d'une dérégulation profonde en amont du gène cyp19a1a, avec comme conséquence une instabilité précoce de la différenciation ovarienne suivie par la masculinisation effective d'une partie des animaux XXmal. Cette instabilité serait amplifiée par des températures élevées qui affecteraient à la fois le développement global des animaux XXmal et la transcription de cyp19a1a. Nos résultats suggèrent fortement que le phénotype "mal" est plus complexe qu'un simple phénotype "femelle masculinisée".

In many rivers, dams have interrupted the connectivity of migration routes for fish. While fishways can provide access between downstream and upstream habitats, it is important that passage can occur with minimal delay, energy expenditure, and physiological stress. The research presented here is based on investigations into fishway attraction and passage for the Gates Creek sockeye salmon (Oncorhynchus nerka, Walbaum) stock at the Seton River dam in British Columbia. The first part of this thesis examined the effect of changes in water discharge from the dam on the relationship between the physiological condition of sockeye and their behaviour in approaching the fishway entrance. Fish were caught and non-lethally biopsied under three normal operating discharge conditions at Seton River dam, and subsets of sampled fish were implanted with radio transmitters and released downstream of the dam. Indices of physiological stress and exhaustive exercise (e.g. plasma cortisol, glucose, lactate, osmolality and hematocrit) did not differ among the water discharge levels that were examined. Fish delayed in the tailrace below the fishway entrance significantly longer under intermediate discharge (19.9 h @ 12.7 m³s‾¹) than either the high discharge (9.3 h @ 15.8 m³s‾¹), or the low discharge (7.0 h @11.0 m³s‾¹;) conditions (P = 0.022, and P = 0.015, respectively). Delay time was similar under high and low discharge conditions (P = 0.617), and passage success was found to be independent of discharge (P = 0.356). The second part of this thesis investigated how prior physiological condition and subsequent swimming energetics and behaviours effected fishway passage success. Fish were captured and biopsied, before being implanted with electromyogram (EMG) transmitters and released near the downstream entrance of the fishway. Very few differences existed between successful and unsuccessful fish in body size, initial plasma physiology and energy state, and mean swim speed and energy use during passage. However, plasma Na+ concentration was significantly lower in unsuccessful fish (P = 0.022), which is suggestive of a depressed ionic state for unsuccessful fish. Generally, fish did not employ burst swimming during successful or failed attempts at passage, indicating that failure was probably not related to metabolic acidosis.

In many rivers, dams have interrupted the connectivity of migration routes for fish. While fishways can provide access between downstream and upstream habitats, it is important that passage can occur with minimal delay, energy expenditure, and physiological stress. The research presented here is based on investigations into fishway attraction and passage for the Gates Creek sockeye salmon (Oncorhynchus nerka, Walbaum) stock at the Seton River dam in British Columbia. The first part of this thesis examined the effect of changes in water discharge from the dam on the relationship between the physiological condition of sockeye and their behaviour in approaching the fishway entrance. Fish were caught and non-lethally biopsied under three normal operating discharge conditions at Seton River dam, and subsets of sampled fish were implanted with radio transmitters and released downstream of the dam. Indices of physiological stress and exhaustive exercise (e.g. plasma cortisol, glucose, lactate, osmolality and hematocrit) did not differ among the water discharge levels that were examined. Fish delayed in the tailrace below the fishway entrance significantly longer under intermediate discharge (19.9 h @ 12.7 m³s‾¹) than either the high discharge (9.3 h @ 15.8 m³s‾¹), or the low discharge (7.0 h @11.0 m³s‾¹;) conditions (P = 0.022, and P = 0.015, respectively). Delay time was similar under high and low discharge conditions (P = 0.617), and passage success was found to be independent of discharge (P = 0.356). The second part of this thesis investigated how prior physiological condition and subsequent swimming energetics and behaviours effected fishway passage success. Fish were captured and biopsied, before being implanted with electromyogram (EMG) transmitters and released near the downstream entrance of the fishway. Very few differences existed between successful and unsuccessful fish in body size, initial plasma physiology and energy state, and mean swim speed and energy use during passage. However, plasma Na+ concentration was significantly lower in unsuccessful fish (P = 0.022), which is suggestive of a depressed ionic state for unsuccessful fish. Generally, fish did not employ burst swimming during successful or failed attempts at passage, indicating that failure was probably not related to metabolic acidosis.

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No. of bitstreams: 1 yoshida_gm_dr_jabo.pdf: 1722466 bytes, checksum: 3b9d699968bdca5ed4d5856648c5403d (MD5) Previous issue date: 2018-02-26 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os objetivos deste trabalho foram: (i) testar a eficiência do algoritmo de seleção de acasalamento (MS) em controlar o nível de endogamia e coascendência, além de aumentar os ganhos genéticos; (ii) incluir a variabilidade genética da futura progênie como componente de otimização na função objetiva de seleção de acasalamento usando dados de dois programas de melhoramento aquícolas; e (iii) comparar a MS com a seleção truncada (TS) e contribuição genética ótima (OCS), combinados com diferentes estratégias de acasalamentos para controlar a endogamia e manter os mesmo níveis de ganhos genéticos. Para os objetivos (i) e (ii), o total de 8.782 tilápias do Nilo (NT) de cinco gerações e 79.144 salmões coho (CS) de oito gerações foram utilizados para otimizar as funções objetivos e vinte gerações discretas foram simuladas para o objetivo (iii), considerando 50 famílias e 2.000 filhos por geração, e uma característica com herdabilidade igual a 0.30. As OFs foram otimizadas considerando a coascendência média dos pais, o mérito genético esperado, a endogamia da futura progênie para os objetivos (i) e (iii) e a variabilidade genética da futura progênie foi adicionada na OF para o objetivo (ii). Para o objetivo (i), a MS permitiu reduzir a endogamia em até 73% para tilápia do Nilo, em comparação com a seleção truncada e até 20% para o salmão coho, em comparação com o cenário real de acasalamento. No objetivo dois, a MS permitiu produzir progênie com maior (DP = 0.77 e 0.30 para NT e CS, respectivamente) ou menor (DP = 0.25 e 0.14 para NT e CS, respectivamente) dispersão dos valores genéticos, dependendo da função objetivo otimizada. A seleção de acasalamentos superou a seleção truncada e o cenário real de acasalamento e também foi possível alterar a variabilidade genética da futura progênie, quando esse componente foi considerado na OF utilizado os dados reais. Para os dados simulados, a MS teve melhor performance comparada com a TS e a OCS combinada com acasalamentos aleatórios. A curto-prazo, a MS foi mais eficiente do que a OCS combinada com os acasalamentos que minimizam a endogamia em controlar a endogamia sob o mesmo nível de ganho genético. Porém, a longo prazo os resultados entre as duas estratégias foram muito semelhantes. De forma geral, o algoritmo de seleção de acasalamentos foi eficiente e flexível em otimizar a função objetiva usando diferentes componentes, em diferentes aplicações práticas na aquicultura. / The aims of this work were: (i) test the efficiency of mate selection (MS) algorithm in controlling the inbreeding and coancestry level, as well, increase the genetic gain; (ii) include the genetic variability of the future progeny as component for the optimization of the MS objective function in two aquaculture real dataset; and (iii) compare MS among truncation selection (TS) and optimum contribution selection (OCS) scenarios combined to different mating strategies to assess the best method in controlling inbreeding and maintain the genetic gain, for aquaculture breeding using simulated dataset. For objective (i) and (ii), a total of 8,782 Nile tilapias (NT) from five generations and 79,144 coho salmon (CS) from eight generations were used to optimize the objective functions (OF) and twenty discrete generations were simulated for the objective (iii), considering 50 families and 2,000 offspring per generation, and a trait with heritability of 0.30. The OFs were optimized accounting to coancestry of parents, expected genetic merit and inbreeding of the future progeny for the objective (i) and (iii) and in addition the genetic variability of the future progeny was considered for the objective (ii). For the objective (i), the mate selection allowed reducing inbreeding up to 73% for NT, compared with truncation selection, and up to 20% for CS, compared with realized scenario. In the objective (ii), MS allowed producing animals with higher (SD = 0.77 and 0.30 for NT and CS, respectively) or lower (SD = 0.25 and 0.14 for NT and CS, respectively) dispersion of estimated breeding value, depending on the objective function optimized. For real data set the MS outperformed the real mates and truncation selection and in addition the genetic variability of the future progeny could be changed when this component was considered in the OF. For the simulated dataset, the MS outperformed the TS and OCS followed by random mating. In the short-term, MS was more efficient than OCS + inbreeding minimizing in controlling inbreeding under the same genetic gain. However, in the long-term, OCS and MS resulted in similar genetic progress and average inbreeding, under the same weight on coancestry. In general, the mate selection algorithm was efficient and flexible to optimize objective functions accounting for different components, under practical applications in aquaculture breeding. / 14/20626-4 e 15/25232-7

In many rivers, dams have interrupted the connectivity of migration routes for fish. While fishways can provide access between downstream and upstream habitats, it is important that passage can occur with minimal delay, energy expenditure, and physiological stress. The research presented here is based on investigations into fishway attraction and passage for the Gates Creek sockeye salmon (Oncorhynchus nerka, Walbaum) stock at the Seton River dam in British Columbia. The first part of this thesis examined the effect of changes in water discharge from the dam on the relationship between the physiological condition of sockeye and their behaviour in approaching the fishway entrance. Fish were caught and non-lethally biopsied under three normal operating discharge conditions at Seton River dam, and subsets of sampled fish were implanted with radio transmitters and released downstream of the dam. Indices of physiological stress and exhaustive exercise (e.g. plasma cortisol, glucose, lactate, osmolality and hematocrit) did not differ among the water discharge levels that were examined. Fish delayed in the tailrace below the fishway entrance significantly longer under intermediate discharge (19.9 h @ 12.7 m³s‾¹) than either the high discharge (9.3 h @ 15.8 m³s‾¹), or the low discharge (7.0 h @11.0 m³s‾¹;) conditions (P = 0.022, and P = 0.015, respectively). Delay time was similar under high and low discharge conditions (P = 0.617), and passage success was found to be independent of discharge (P = 0.356). The second part of this thesis investigated how prior physiological condition and subsequent swimming energetics and behaviours effected fishway passage success. Fish were captured and biopsied, before being implanted with electromyogram (EMG) transmitters and released near the downstream entrance of the fishway. Very few differences existed between successful and unsuccessful fish in body size, initial plasma physiology and energy state, and mean swim speed and energy use during passage. However, plasma Na+ concentration was significantly lower in unsuccessful fish (P = 0.022), which is suggestive of a depressed ionic state for unsuccessful fish. Generally, fish did not employ burst swimming during successful or failed attempts at passage, indicating that failure was probably not related to metabolic acidosis. / Forestry, Faculty of / Graduate

An investigation was initiated in southern British Columbia during 1984 to determine the degree of similarity between populations of coho salmon, in terms of their demographic traits and exploitation patterns. Fourteen stocks of wild or hatchery origin were subject to coded-wire tagging in nine different streams located within a 150 km region of southeast Vancouver Island during 1985,1986, and 1987. Escapement enumeration and tag recovery were conducted during the 1985-1988 period in all streams by means of counting fences and stream surveys. A new mark-recapture model was formulated specifically for estimating escapement levels in natural streams where only a partial enumeration of spawners is possible. Estimates of the number of tags recovered in various sport and commercial fisheries were generated primarily on the basis of catch and sampling records extracted from the Mark-Recovery Program database, located at the Pacific Biological Station of the Canadian Department of Fisheries and Oceans. Estimates of sampling rates in the Strait of Georgia sport fishery were determined from simulation studies based on catch and sampling statistics associated with the Georgia Strait Creel Survey and Head Recovery programs. Populations were contrasted in terms of their juvenile migration patterns, smolt-to-adult survival, catch distributions, straying rates, escapement patterns, run composition, adult sizes, and exploitation rates. Considerable variation in smolt size and juvenile migration time was detected among populations each year. The most pronounced difference was the consistently shorter migration period of smolts released from public hatcheries. Estimates of ocean survival was highly variable across years and streams, and even among stocks within the same stream. No particular stock or stock type had consistently higher survival, but hatchery fish from the Big Qualicum River exhibited consistently lower survival. Considerable variation was observed in the duration and timing of various runs within the study area. On average, the contribution of strays to each spawning population was relatively small (< 2%), but strays could account for as much as 50% of the escapement to a given stream. Average exploitation rates were in the neighborhood of 80% each year, but were as high as 96% for some stocks. Substantial differences in exploitation rate were detected between stocks from the same stream, and between stocks from adjacent streams, but exploitation rates were not consistently higher or lower for any particular stock or stock type. The influence of specific factors upon straying rates, survival rates and exploitation patterns was estimated by means of log-linear models. Stock contributions to various fisheries appeared to be related to the release location, and two stock assemblages were identified within the study area based on the level of similarity among stocks in fishery contribution. Attempts to quantify the level of co-variation among stocks in survival and exploitation rates were hampered by the lack of sufficiently long time series of data, but preliminary results gave no indication of a high level of similarity among stocks or stock types. Still, it was possible to identify stocks which could be used as indicators of the general status of all stocks in the study area in terms of escapement trends, smolt-to-adult survival and exploitation rates. Based on the level of similarity observed, indicator stocks are considered to be useful stock-assessment tools, and can provide useful information for management purposes. / Science, Faculty of / Zoology, Department of / Graduate

Recovery from exhaustive exercise in the white muscle of rainbow trout (Oncorhynchus mykiss) was used to examine the role of the adenylates in the control of energy metabolism and to assess the validity of equilibrium models of the behaviour of the high energy phosphates. The difficulty of obtaining muscle samples from fish makes detailed analysis of the behaviour of the labile high energy phosphates complex. The use of a new sampling procedure, the infusion of a lethal dose of anaesthetic via an indwelling cannula, minimized this problem. At exhaustion [ATP] and [PCr] were depressed by 75 and 80% respectively relative to the resting values. [ATP] depletion was mirrored by a stoichiometric increase in [IMP]. During recovery [PCr] returned to the resting level within 2 hours, but [ATP] recovery was slow and not complete until 24 hours post exercise. In contrast, energy charge and RATP(the proportion of the free adenylate pool phosphorylated to ATP) were, if anything, higher than the resting values by 2 hours post exercise. Therefore, [ATP] and energy status can be dissociated in tissues like fish white muscle because of the action of the purine nucleotide cycle. At 2 hours post exercise the calculated free ADP concentration dropped to less than one tenth the value at rest. As a result the [ATP] / [ADP] free ratio increased by nearly 6 fold. This condition may be required for glycogen resynthesis from lactate in muscle. Several similar equilibrium models of the behaviour of the adenylates and PCr were applied to the fish white muscle system. In general, the models well describe the relationship between the high energy phosphates. However, the definition of the high energy phosphate pool introduces some complications since this includes the total [ATP]. Because of the action of AMP deaminase the [ATP] concentration can change without measurable changes in the energy status, which is not considered in any of the models. As long as the extent of IMP formation is known the models can be applied, but since the formation of IMP may vary from fish to fish or with exercise regime the models lose much of their predictive power. / Science, Faculty of / Zoology, Department of / Graduate

The effect of transferring fish from water at pH 7.0 to either more acid or more alkaline conditions was to reduce the maximum critical velocity of the fish. In water of pH 4.0, 5.0, and 10.0, the maximum critical velocity was only 54.5%, 66.5%, and 61% respectively of that recorded for fish in the water of pH 7.0. Thus, both acid and alkaline conditions in the water reduce the aerobic swimming capacity of trout. Exposure to acid conditions increased mucus secretion and this was associated with an increase in coughing and breathing frequency in resting fish. Coughing rate increased from 41/hr to 592/hr; and respiration frequency increased from 81/min to 104/min when fish were transferred from water at pH 7.0 to water at pH 4.0. In comparing fish exposed to acid and alkaline waters, the results indicates that fish have a greater capacity to regulate blood pH in acid than in alkaline conditions. The gill potential was strongly dependent on water pH, being negative in neutral water, but positive in acid water and more negative in alkaline solution. Catecholamine levels increased significantly during acid exposure, but were not altered during alkaline exposure. The increasing catecholamine levels appeared at different time periods in different fish during acid exposure and seemed to be associated with the death of the fish. Na⁺ and C1⁻ ion concentrations in plasma decreased significantly after 24hrs of acid exposure, but did not change significantly in alkaline water. This may indicate that ionoregulatory disturbance in plasma is one of the reasons for the decrease in the maximum critical velocity in acid water, but not in alkaline water. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

Disease has been identified as a major problem in the aquaculture industry for the welfare of the fish stocked as well as for its economic impact. The number of diseases affecting cultured fish has increased significantly during recent years with the emergence of several conditions that have added to the overall impact of disease on the industry. Frequently, a lack of scientific knowledge about these diseases is compounded by an absence of effective treatment and control strategies. This has been the case with rainbow trout gastroenteritis (RTGE), an emerging disease of rainbow trout (Oncorhynchus mykiss Walbaum). This study investigated several aspects related to its aetiology and control. A retrospective survey of UK rainbow trout farmers was undertaken to ascertain the extent and severity of RTGE in the UK as well as to identify RTGE risk factors at the site level. Participants in this study accounted for over 85% of UK rainbow trout production in 2004. It was found that the total number of RTGE-affected sites had risen from 2 in the year 2000 to 7 in 2005. The disease was only reported from sites producing more than 200 tonnes of trout/year for the table market. Analysis of risk factors associated with RTGE at the site level showed that this syndrome was associated with large tonnage and rapid production of rainbow trout for the table market. The data collected during this study enabled the identification of those sites that were most likely to present with RTGE the following year and this information was used to study the epidemiology of RTGE at the unit level. A prospective longitudinal study was undertaken in 12 RTGE-affected UK sites. It described in detail the impact, presentation, current control strategies and spread pattern of RTGE within affected UK sites. The risk factors associated with RTGE presence and severity were also investigated. Data were collected for each productive unit (i.e. cage, pond, raceway or tank) on the mortalities, fish origin, site management and environmental factors. RTGE was identified using a case definition based on gross pathological lesions. Analysis of these data revealed that RTGE behaved in an infectious manner. This conclusion was supported by the presence of a pattern typical of a propagating epidemic within affected units. Also, the risk of an unaffected unit becoming RTGE positive was increased if it had received fish from or was contiguous to a RTGE-affected unit. The presentation also suggested an incubation period of 20-25 days. Risk factor analysis identified management and environmental risk factors for RTGE, including high feed input and stressful events, which could be used to generate a list of control strategies. A study of the histopathological and ultrastructural presentation of RTGE was conducted. The location of segmented filamentous bacteria (SFB) and pathological changes found in affected fish were examined. Pyloric caeca were the digestive organ where SFB were found more frequently and in higher numbers, suggesting that this was the best location to detect SFB in RTGE-affected trout. Scanning and transmission electron microscopy revealed a previously undescribed interaction of SFB with the mucosa of distal intestine and pyloric caeca and this included the presence of attachment sites and SFB engulfment by enterocytes, as previously described in other host species. The SFB were not always adjacent to the pathological changes observed in the digestive tract of RTGE-affected trout. Such changes included cytoskeletal damage and osmotic imbalance of enterocytes, with frequent detachment. These observations suggested that if SFB are indeed the cause of RTGE their pathogenesis must involve the production of extracellular products. Analysis of the gross presentation and blood biochemistry in RTGE-affected fish was used to examine the patho-physiologic mechanisms of RTGE. To enable identification of positive RTGE cases for this study, a case definition was created from the information available on RTGE gross presentation in the literature. This case definition was assessed in a sample including 152 fish cases and 152 fish controls from 11 RTGE-affected UK sites, matched by unit of origin. The analysis of these fish using bacteriology, packed cell volume (PCV) and histopathology revealed that RTGE occurred simultaneously with other parasitic and bacterial diseases in a percentage of fish identified with this case definition. With the information gained after analysing the gross presentation, RTGE-affected fish without concurrent disease were selected for the study of the pathogenesis, which included blood biochemical analyses. These analyses revealed a severe osmotic imbalance, and a reduced albumin/globulin ratio suggesting selective loss of albumin, typical for a protein losing enteropathy. The role of the SFB “Candidatus arthromitus” in the aetiology of RTGE was assessed using a newly developed “C. arthromitus”-specific polymerase chain reaction assay (PCR) in conjunction with histological detection. This technique was applied to eight different groups of trout, including an RTGE-affected group and seven negative control groups. This analysis was conducted on DNA extracted from paraffin wax-embedded tissues as well as fresh intestinal contents. The results revealed the presence of “C. arthromitus” DNA in apparently healthy fish from sites where RTGE had never been reported. Additionally, SFB were observed histologically in two trout from an RTGE-free hatchery. These findings do not permit the exclusion of “C. arthromitus” as the aetiological agent for RTGE, although they suggest that the presence of these organisms in the digestive system of healthy trout is not sufficient to cause clinical disease, and therefore other factors are necessary. In conclusion, this study has used a multidisciplinary approach to the study of RTGE which has generated scientific information related to the epidemiology, pathogenesis and aetiology of this syndrome. The results of this project have suggested priority areas where further work is required, including experimental transmission of RTGE, field assessment of the control strategies proposed and further investigation into the aetiology of RTGE.