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• 1121. [Article] Appraisal of Fresh Fish Marketing in Ondo State, Nigeria

  This is part of the IIFET Special Session on Markets and Value Chains for Small Aquaculture & Fisheries Enterprises with a Focus on Gender that took place on 17 July 2012 in Dar Es Salaam, Tanzania in ...

  Citation × Citation Citation Abstract Copy Title: Appraisal of Fresh Fish Marketing in Ondo State, Nigeria Author: Afolabi, J.A., Adeleke, M.L. This is part of the IIFET Special Session on Markets and Value Chains for Small Aquaculture & Fisheries Enterprises with a Focus on Gender that took place on 17 July 2012 in Dar Es Salaam, Tanzania in conjunction with 16th IIFET Conference. The complete proceedings of this special session are available (http://aquafishcrsp.oregonstate.edu/Documents/Uploads/FileManager/IIFET%202012%20CRSP%20Session%20Proceedings%20Final_small.pdf) through the Aquaculture & Fisheries Collaborative Research Support Program gender web site, (http://aquafishcrsp.oregonstate.edu/Gender/). Title: Appraisal of Fresh Fish Marketing in Ondo State, Nigeria Author: Afolabi, J.A., Adeleke, M.L. This is part of the IIFET Special Session on Markets and Value Chains for Small Aquaculture & Fisheries Enterprises with a Focus on Gender that took place on 17 July 2012 in Dar Es Salaam, Tanzania in conjunction with 16th IIFET Conference. The complete proceedings of this special session are available (http://aquafishcrsp.oregonstate.edu/Documents/Uploads/FileManager/IIFET%202012%20CRSP%20Session%20Proceedings%20Final_small.pdf) through the Aquaculture & Fisheries Collaborative Research Support Program gender web site, (http://aquafishcrsp.oregonstate.edu/Gender/). Close

• 1122. [Article] Marketing, Distribution and Consumption of Frozen Fish in Anyigba Metropolis of Kogi State, Nigeria

  The study was carried out in Anyigba metropolis in central Nigeria to analyse the distribution, marketing and consumption of frozen fish. Twenty (20) retailers and 60 consumers were randomly selected for ...

  Citation × Citation Citation Abstract Copy Title: Marketing, Distribution and Consumption of Frozen Fish in Anyigba Metropolis of Kogi State, Nigeria Author: Ogbe, Friday Garba, Danjuma, Asabe, Onuche, Unekwu The study was carried out in Anyigba metropolis in central Nigeria to analyse the distribution, marketing and consumption of frozen fish. Twenty (20) retailers and 60 consumers were randomly selected for questionnaire administration. Descriptive statistics, marketing margin analysis, the gross margin approach to profitability analysis and regression analysis were used. Findings revealed that frozen fish trade was largely in the hands of young uneducated women and was profitable. It was also revealed that most consumers preferred Ethmalosa fimbriata (bonga fish) on account of its low price. The Market margin analyses show a good motivation for continuity in the business although there is need for caution in pricing as consumption of frozen food in the area was price elastic in the fashion of normal goods. Regression results revealed that increase in factors like amount spent on meat, price, income and transportation cost reduced the level of fish consumption while increase in years of schooling, family size and age were positively related to fish consumption. Patronage of Fish in the area appears to be high judging from the profitability level of the trade. Some of the problems militating against the trade include poor power supply, high storage cost and poor road network. Recommendations made include among others, improvement in power supply, encouragement of adult education so as to increase effectiveness of the trade and encourage consumption by consumers, and introduction of other species of frozen fish in order to increase consumers’ choices. Key words: frozen fish, marketers, profitability, determinants, consumption Title: Marketing, Distribution and Consumption of Frozen Fish in Anyigba Metropolis of Kogi State, Nigeria Author: Ogbe, Friday Garba, Danjuma, Asabe, Onuche, Unekwu The study was carried out in Anyigba metropolis in central Nigeria to analyse the distribution, marketing and consumption of frozen fish. Twenty (20) retailers and 60 consumers were randomly selected for questionnaire administration. Descriptive statistics, marketing margin analysis, the gross margin approach to profitability analysis and regression analysis were used. Findings revealed that frozen fish trade was largely in the hands of young uneducated women and was profitable. It was also revealed that most consumers preferred Ethmalosa fimbriata (bonga fish) on account of its low price. The Market margin analyses show a good motivation for continuity in the business although there is need for caution in pricing as consumption of frozen food in the area was price elastic in the fashion of normal goods. Regression results revealed that increase in factors like amount spent on meat, price, income and transportation cost reduced the level of fish consumption while increase in years of schooling, family size and age were positively related to fish consumption. Patronage of Fish in the area appears to be high judging from the profitability level of the trade. Some of the problems militating against the trade include poor power supply, high storage cost and poor road network. Recommendations made include among others, improvement in power supply, encouragement of adult education so as to increase effectiveness of the trade and encourage consumption by consumers, and introduction of other species of frozen fish in order to increase consumers’ choices. Key words: frozen fish, marketers, profitability, determinants, consumption Close

• 1123. [Article] Women in Fish Value Chain in Nigeria

  This is part of the IIFET Special Session on Markets and Value Chains for Small Aquaculture & Fisheries Enterprises with a Focus on Gender that took place on 17 July 2012 in Dar Es Salaam, Tanzania in ...

  Citation × Citation Citation Abstract Copy Title: Women in Fish Value Chain in Nigeria Author: Cheke, Abiodun This is part of the IIFET Special Session on Markets and Value Chains for Small Aquaculture & Fisheries Enterprises with a Focus on Gender that took place on 17 July 2012 in Dar Es Salaam, Tanzania in conjunction with 16th IIFET Conference. The complete proceedings of this special session are available (http://aquafishcrsp.oregonstate.edu/Documents/Uploads/FileManager/IIFET%202012%20CRSP%20Session%20Proceedings%20Final_small.pdf) through the Aquaculture & Fisheries Collaborative Research Support Program gender web site, (http://aquafishcrsp.oregonstate.edu/Gender/). Title: Women in Fish Value Chain in Nigeria Author: Cheke, Abiodun This is part of the IIFET Special Session on Markets and Value Chains for Small Aquaculture & Fisheries Enterprises with a Focus on Gender that took place on 17 July 2012 in Dar Es Salaam, Tanzania in conjunction with 16th IIFET Conference. The complete proceedings of this special session are available (http://aquafishcrsp.oregonstate.edu/Documents/Uploads/FileManager/IIFET%202012%20CRSP%20Session%20Proceedings%20Final_small.pdf) through the Aquaculture & Fisheries Collaborative Research Support Program gender web site, (http://aquafishcrsp.oregonstate.edu/Gender/). Close

• 1124. [Article] The Promotion of Responsible Trawl Fishing Practices in South East Asia : The Introduction of Juvenile and Trash Excluder Devices (JTEDs)

  Research Paper

  Citation × Citation Citation Abstract Copy Title: The Promotion of Responsible Trawl Fishing Practices in South East Asia : The Introduction of Juvenile and Trash Excluder Devices (JTEDs) Author: Chokesanguan, Bundit Research Paper Title: The Promotion of Responsible Trawl Fishing Practices in South East Asia : The Introduction of Juvenile and Trash Excluder Devices (JTEDs) Author: Chokesanguan, Bundit Research Paper Close

• 1125. [Article] Effects of dietary selenium and fish oil (MaxEPA) on arachidonic acid metabolism and hemostatic function in the rat

  The purpose of this study was to investigate whether the beneficial effects which the consumption of fish oil imparts on hemostatic function can be modified by the level of dietary selenium. Male Sprague ...

  Citation × Citation Citation Abstract Copy Title: Effects of dietary selenium and fish oil (MaxEPA) on arachidonic acid metabolism and hemostatic function in the rat Author: Song, Jihyun The purpose of this study was to investigate whether the beneficial effects which the consumption of fish oil imparts on hemostatic function can be modified by the level of dietary selenium. Male Sprague Dawley rats were fed for eight weeks semipurified diets containing 7% corn oil (by weight) or 5.5% fish oil (MaxEPA) plus 1.5% corn oil with or without selenium supplementation. The indicators of selenium status (glutathione peroxidase activity and selenium level) were significantly lower in the rats given inadequate selenium, regardless of the type of fat fed. In the animals fed adequate selenium, these same indicators tended to be lower when fish oil was fed. Although feeding of fish oil increased hepatic and aortic malondialdehyde (MDA), selenium supplementation decreased its level in the liver. Selenium deficiency led to a decrease in the relative weight percent of 22:6 n-3 in aorta and plasma. Increases in the levels of 20:5 n-3, 22:5 n-3, 22:6 n-3, 20:3 n-6 and a decrease in the level of 20:4 n-6 were observed in plasma total lipids and aortic and hepatic phospholipids when fish oil was fed. The increased level of 20:3 n-6 suggests that delta 5-desaturase activity was decreased by fish oil feeding. The level of aortic 6-keto-prostaglandin F₁alpha (6- keto-PGF₁alpha) was highest in the rats fed diets that contained corn oil but no selenium supplementation; selenium supplementation, however, eliminated the difference in the level of 6-keto-PGF₁alpha between fish oil and corn oil fed groups. The levels of thromboxane B₂ (TXB₂) and ADP-induced platelet aggregation were decreased significantly by fish oil feeding and tended to be lower with selenium supplementation. Selenium supplementation did not increase bleeding time while fish oil feeding did. These data indicate that selenium supplementation may decrease fish oil induced lipid peroxidation in liver: this is reflected in the lower hepatic MDA levels in the fish oil fed animals with selenium supplementation and the increased 22:6 n-3 levels in aorta and plasma. Selenium deficiency led to an increase in the level of 6-keto-PGF₁alpha in the rats fed corn oil. Its effects on TXB₂ level and ADP-induced platelet aggregation are marginal. Overall the beneficial effect of selenium supplementation on hemostatic function appears weaker than that of fish oil feeding. Title: Effects of dietary selenium and fish oil (MaxEPA) on arachidonic acid metabolism and hemostatic function in the rat Author: Song, Jihyun The purpose of this study was to investigate whether the beneficial effects which the consumption of fish oil imparts on hemostatic function can be modified by the level of dietary selenium. Male Sprague Dawley rats were fed for eight weeks semipurified diets containing 7% corn oil (by weight) or 5.5% fish oil (MaxEPA) plus 1.5% corn oil with or without selenium supplementation. The indicators of selenium status (glutathione peroxidase activity and selenium level) were significantly lower in the rats given inadequate selenium, regardless of the type of fat fed. In the animals fed adequate selenium, these same indicators tended to be lower when fish oil was fed. Although feeding of fish oil increased hepatic and aortic malondialdehyde (MDA), selenium supplementation decreased its level in the liver. Selenium deficiency led to a decrease in the relative weight percent of 22:6 n-3 in aorta and plasma. Increases in the levels of 20:5 n-3, 22:5 n-3, 22:6 n-3, 20:3 n-6 and a decrease in the level of 20:4 n-6 were observed in plasma total lipids and aortic and hepatic phospholipids when fish oil was fed. The increased level of 20:3 n-6 suggests that delta 5-desaturase activity was decreased by fish oil feeding. The level of aortic 6-keto-prostaglandin F₁alpha (6- keto-PGF₁alpha) was highest in the rats fed diets that contained corn oil but no selenium supplementation; selenium supplementation, however, eliminated the difference in the level of 6-keto-PGF₁alpha between fish oil and corn oil fed groups. The levels of thromboxane B₂ (TXB₂) and ADP-induced platelet aggregation were decreased significantly by fish oil feeding and tended to be lower with selenium supplementation. Selenium supplementation did not increase bleeding time while fish oil feeding did. These data indicate that selenium supplementation may decrease fish oil induced lipid peroxidation in liver: this is reflected in the lower hepatic MDA levels in the fish oil fed animals with selenium supplementation and the increased 22:6 n-3 levels in aorta and plasma. Selenium deficiency led to an increase in the level of 6-keto-PGF₁alpha in the rats fed corn oil. Its effects on TXB₂ level and ADP-induced platelet aggregation are marginal. Overall the beneficial effect of selenium supplementation on hemostatic function appears weaker than that of fish oil feeding. Close

• 1126. [Article] Husbandry stress of Zebrafish, Danio rerio

  Zebrafish, Danio rerio, are widely used as vertebrate research organisms yet little is know about their responses to husbandry stressors. This dissertation examined the whole-body cortisol responses of ...

  Citation × Citation Citation Abstract Copy Title: Husbandry stress of Zebrafish, Danio rerio Author: Ramsay, Jenniifer Mara, 1975- Zebrafish, Danio rerio, are widely used as vertebrate research organisms yet little is know about their responses to husbandry stressors. This dissertation examined the whole-body cortisol responses of zebrafish to husbandry stress. Additionally, the effects of stress on the susceptibility to mycobacteriosis and microsporidiosis (Pseudoloma neurophilia) were determined including effects on growth and reproduction. In Chapter 2, crowding increased cortisol but this was modulated by fasting and feeding; fasted but not fed fish elevated cortisol when crowded. Fish weight was inversely related to cortisol level in fasted, crowded fish. In Chapter 3, zebrafish rapidly responded to net handling stressors with a 6-fold increase in whole-body cortisol which peaked at 15 min post-net-stress. Cortisol recovered to control levels by 60 min. The variability in resting cortisol increased with fish age. In Chapter 4, fish infected with Mycobacterium marinum and subjected to husbandry stressors had 14% cumulative mortality over 8 weeks while no mortality occurred among infected fish without stress. Stressed fish, injected with M. chelonae were 15-fold more likely to be infected than non-stressed fish. Sub-acute, diffuse infections were more common among infected fish that were stressed than those not stressed. In Chapter 5, we examined the effects of stress on pre-existing and experimental Pseudoloma infections and the subsequent effects on survival, growth, and reproduction. Stress increased mortality and myositis in fish with pre-existing infections. There was no mortality among fish experimentally infected with Pseudoloma regardless of stress treatment. The onset of infection occurred sooner in stressed fish and stress significantly increased the mean intensity of infection. Weight decreased in stressed and experimentally infected groups from week 13 to 20 post-exposure but not in the control group. Fecundity was negatively related to mean parasite area among Pseudoloma-infected and stressed fish. Whole-body cortisol is an indicator of crowding and handling stress in zebrafish. Husbandry stressors exacerbated mycobacteriosis and microsporidiosis in zebrafish with associated reductions in growth and fecundity. Zebrafish are hardy and well adapted to a laboratory environment. Nevertheless, reducing stress should aid in preventing disease outbreaks and maintaining growth and fecundity of this popular laboratory fish species. Title: Husbandry stress of Zebrafish, Danio rerio Author: Ramsay, Jenniifer Mara, 1975- Zebrafish, Danio rerio, are widely used as vertebrate research organisms yet little is know about their responses to husbandry stressors. This dissertation examined the whole-body cortisol responses of zebrafish to husbandry stress. Additionally, the effects of stress on the susceptibility to mycobacteriosis and microsporidiosis (Pseudoloma neurophilia) were determined including effects on growth and reproduction. In Chapter 2, crowding increased cortisol but this was modulated by fasting and feeding; fasted but not fed fish elevated cortisol when crowded. Fish weight was inversely related to cortisol level in fasted, crowded fish. In Chapter 3, zebrafish rapidly responded to net handling stressors with a 6-fold increase in whole-body cortisol which peaked at 15 min post-net-stress. Cortisol recovered to control levels by 60 min. The variability in resting cortisol increased with fish age. In Chapter 4, fish infected with Mycobacterium marinum and subjected to husbandry stressors had 14% cumulative mortality over 8 weeks while no mortality occurred among infected fish without stress. Stressed fish, injected with M. chelonae were 15-fold more likely to be infected than non-stressed fish. Sub-acute, diffuse infections were more common among infected fish that were stressed than those not stressed. In Chapter 5, we examined the effects of stress on pre-existing and experimental Pseudoloma infections and the subsequent effects on survival, growth, and reproduction. Stress increased mortality and myositis in fish with pre-existing infections. There was no mortality among fish experimentally infected with Pseudoloma regardless of stress treatment. The onset of infection occurred sooner in stressed fish and stress significantly increased the mean intensity of infection. Weight decreased in stressed and experimentally infected groups from week 13 to 20 post-exposure but not in the control group. Fecundity was negatively related to mean parasite area among Pseudoloma-infected and stressed fish. Whole-body cortisol is an indicator of crowding and handling stress in zebrafish. Husbandry stressors exacerbated mycobacteriosis and microsporidiosis in zebrafish with associated reductions in growth and fecundity. Zebrafish are hardy and well adapted to a laboratory environment. Nevertheless, reducing stress should aid in preventing disease outbreaks and maintaining growth and fecundity of this popular laboratory fish species. Close

• 1127. [Article] Seasonal floodplain wetlands as fish habitat in Oregon and Washington

  To begin to understand freshwater seasonal floodplain fish communities in the context of human alteration of the physical system, species introductions and wetland restoration efforts, I studied fish assemblages ...

  Citation × Citation Citation Abstract Copy Title: Seasonal floodplain wetlands as fish habitat in Oregon and Washington Author: Baker, Cynthia F. To begin to understand freshwater seasonal floodplain fish communities in the context of human alteration of the physical system, species introductions and wetland restoration efforts, I studied fish assemblages in fifteen seasonal floodplain wetlands within four geographic regions (coastal, upper Columbia River estuary, Puget Sound and eastern Oregon/Washington) in the Pacific Northwest from November through June, 2001 to 2006. Temporal patterns of species richness and diversity in fish assemblages were examined within a hierarchical framework of spatial and temporal factors in the context of the dynamic and variable nature of floodplains. At broad regional scales, fish assemblages diverged along a regional climactic gradient from wet, cool coastal sites to drier sites further inland with greater seasonal temperature fluctuations. Even though wetlands provide a dynamic environment for fish, species richness and diversity at most sites were relatively stable over the winter and spring. Community stability may have been due, in part, to the predictable duration of wetland inundation during winter and spring, but also to the presence of species that fulfill life history requirements (spawning, rearing) in wetlands, and the presence of juvenile salmon throughout the winter and spring. Once fish entered wetlands, wholesale movement of species into and out of wetlands did not occur until summer desiccation. Comparison of fish species richness between each wetland and adjacent rivers revealed that only about 60% of species present in the rivers were found in wetlands, indicating floodplain wetlands were not compatible with the biological traits of almost half of the fish species present in adjacent rivers. Functional groups of species utilized wetlands at different times of year, during different developmental stages, for different durations, and movements into and out of wetlands were triggered mostly by changing water levels. Juvenile salmon movements were triggered by water level, temperature, barometric pressure and lunar phase. Juvenile salmon were present at every wetland site. No evidence was found to support that floodplain wetlands are a ‘predator trap’ for juvenile salmon. Further understanding of the ecological value of floodplain systems may be useful to guide efforts to restore these systems to dynamic, self-sustaining levels of ecosystem function. Title: Seasonal floodplain wetlands as fish habitat in Oregon and Washington Author: Baker, Cynthia F. To begin to understand freshwater seasonal floodplain fish communities in the context of human alteration of the physical system, species introductions and wetland restoration efforts, I studied fish assemblages in fifteen seasonal floodplain wetlands within four geographic regions (coastal, upper Columbia River estuary, Puget Sound and eastern Oregon/Washington) in the Pacific Northwest from November through June, 2001 to 2006. Temporal patterns of species richness and diversity in fish assemblages were examined within a hierarchical framework of spatial and temporal factors in the context of the dynamic and variable nature of floodplains. At broad regional scales, fish assemblages diverged along a regional climactic gradient from wet, cool coastal sites to drier sites further inland with greater seasonal temperature fluctuations. Even though wetlands provide a dynamic environment for fish, species richness and diversity at most sites were relatively stable over the winter and spring. Community stability may have been due, in part, to the predictable duration of wetland inundation during winter and spring, but also to the presence of species that fulfill life history requirements (spawning, rearing) in wetlands, and the presence of juvenile salmon throughout the winter and spring. Once fish entered wetlands, wholesale movement of species into and out of wetlands did not occur until summer desiccation. Comparison of fish species richness between each wetland and adjacent rivers revealed that only about 60% of species present in the rivers were found in wetlands, indicating floodplain wetlands were not compatible with the biological traits of almost half of the fish species present in adjacent rivers. Functional groups of species utilized wetlands at different times of year, during different developmental stages, for different durations, and movements into and out of wetlands were triggered mostly by changing water levels. Juvenile salmon movements were triggered by water level, temperature, barometric pressure and lunar phase. Juvenile salmon were present at every wetland site. No evidence was found to support that floodplain wetlands are a ‘predator trap’ for juvenile salmon. Further understanding of the ecological value of floodplain systems may be useful to guide efforts to restore these systems to dynamic, self-sustaining levels of ecosystem function. Close

• 1128. [Article] A biological and taxonomic study of selected myxosporida of some Oregon fresh-water fishes

  Biological studies were conducted on a histozoic myxosporidan Myxobolus insidiosus (Wyatt and Pratt, 1963) from the musculature of Oncorhynchus tshawytscha (Walbaum). This organism is known to occur in ...

  Citation × Citation Citation Abstract Copy Title: A biological and taxonomic study of selected myxosporida of some Oregon fresh-water fishes Author: Wyatt, Ellis Junior Biological studies were conducted on a histozoic myxosporidan Myxobolus insidiosus (Wyatt and Pratt, 1963) from the musculature of Oncorhynchus tshawytscha (Walbaum). This organism is known to occur in spring chinook salmon in Oregon and coho salmon O. kisutch (Walbaum) in Washington. In addition Myxobolus kisutchi (Yasutake and Wood, 1957) was found in cysts in the brain of a new host, the spring chinook salmon. Salmo clarki clarki (Richardson) was found to be parasitized by a Myxobolus sp. The spore morphology and the location of some cysts in the connective tissue of the striated muscle differ from that of M. insidiosus. Transmission studies on Myxobolus insidiosus in disease free water supplies provided only negative data. Infected tissue from juvenile and adult fish fed to susceptible juvenile salmon failed to produce disease. Contact of non-infected juvenile fish with infected juvenile salmon also failed to produce disease. Uninfected, juvenile fish, continuously exposed to spore-seeded mud for 210 days failed to develop the infection. Mud from an infective area in running spring water was not infective to susceptible fish. Fish placed in rearing ponds receiving water in which fish previously had developed the infection became diseased. Experiments with fish infected in this way provided positive data. The time between exposure to infective water and finding of patent disease was between 76 and 83 days. The disease becomes patent when the average daily water temperature is near 8.4°C. Fish exposed to infective water for a period of eight to 22 days became infected. If the exposure was in February and March, increases in exposure time raised the percent of infection, but similar periods of exposure in May resulted in a reduced incidence of the disease. Data indicate that the McKenzie River water is probably not continuously infective. Placement of fish with the prepatent disease in warmer water caused the disease to become patent and accelerated the time to spore formation. Susceptibility was not dependent on age or size of fish. Spores were found in adult fish that had returned to spawn after four years at sea. Transmission of the disease on or in the egg does not appear to take place. There was a 12.5 percent disease incidence in fish reared in concrete raceway ponds. Fish from dirt rearing ponds which were in series had a 100 percent incidence at the time of liberation. Water turnover rate is important in the epidemiology of the disease. Calcium hydroxide at 0.12 and 0.25 percent caused apparent degeneration of the spores when tested in mud after 216 hours of exposure. Spores in mud with water flowing near them may remain morphologically intact up to 298 days. The nitrofuran drug, Furanace, was ineffective against trophozoites of Chloromyxym sp. and vegetative stages of Myxobolus insidiosus. A diagnosis of Myxobolus insidiosus in juvenile and adult coho salmon in the Lewis River in Washington was confirmed. Autoinfection of juvenile spring chinook with M. insidiosus could not be confirmed. Compact nodular areas made up of fibroblasts and mesenchymal-like cells were found in areas of striated muscle where spore-bearing cysts once occurred. Title: A biological and taxonomic study of selected myxosporida of some Oregon fresh-water fishes Author: Wyatt, Ellis Junior Biological studies were conducted on a histozoic myxosporidan Myxobolus insidiosus (Wyatt and Pratt, 1963) from the musculature of Oncorhynchus tshawytscha (Walbaum). This organism is known to occur in spring chinook salmon in Oregon and coho salmon O. kisutch (Walbaum) in Washington. In addition Myxobolus kisutchi (Yasutake and Wood, 1957) was found in cysts in the brain of a new host, the spring chinook salmon. Salmo clarki clarki (Richardson) was found to be parasitized by a Myxobolus sp. The spore morphology and the location of some cysts in the connective tissue of the striated muscle differ from that of M. insidiosus. Transmission studies on Myxobolus insidiosus in disease free water supplies provided only negative data. Infected tissue from juvenile and adult fish fed to susceptible juvenile salmon failed to produce disease. Contact of non-infected juvenile fish with infected juvenile salmon also failed to produce disease. Uninfected, juvenile fish, continuously exposed to spore-seeded mud for 210 days failed to develop the infection. Mud from an infective area in running spring water was not infective to susceptible fish. Fish placed in rearing ponds receiving water in which fish previously had developed the infection became diseased. Experiments with fish infected in this way provided positive data. The time between exposure to infective water and finding of patent disease was between 76 and 83 days. The disease becomes patent when the average daily water temperature is near 8.4°C. Fish exposed to infective water for a period of eight to 22 days became infected. If the exposure was in February and March, increases in exposure time raised the percent of infection, but similar periods of exposure in May resulted in a reduced incidence of the disease. Data indicate that the McKenzie River water is probably not continuously infective. Placement of fish with the prepatent disease in warmer water caused the disease to become patent and accelerated the time to spore formation. Susceptibility was not dependent on age or size of fish. Spores were found in adult fish that had returned to spawn after four years at sea. Transmission of the disease on or in the egg does not appear to take place. There was a 12.5 percent disease incidence in fish reared in concrete raceway ponds. Fish from dirt rearing ponds which were in series had a 100 percent incidence at the time of liberation. Water turnover rate is important in the epidemiology of the disease. Calcium hydroxide at 0.12 and 0.25 percent caused apparent degeneration of the spores when tested in mud after 216 hours of exposure. Spores in mud with water flowing near them may remain morphologically intact up to 298 days. The nitrofuran drug, Furanace, was ineffective against trophozoites of Chloromyxym sp. and vegetative stages of Myxobolus insidiosus. A diagnosis of Myxobolus insidiosus in juvenile and adult coho salmon in the Lewis River in Washington was confirmed. Autoinfection of juvenile spring chinook with M. insidiosus could not be confirmed. Compact nodular areas made up of fibroblasts and mesenchymal-like cells were found in areas of striated muscle where spore-bearing cysts once occurred. Close

• 1129. [Article] Assessing disease impacts of hatcheries on downstream salmonids in the Willamette River Basin, Oregon

  Hatcheries are often perceived as a source of pathogen amplification, potentially increasing disease risk to free-ranging populations; at the same time, free-ranging fishes may introduce pathogens into ...

  Citation × Citation Citation Abstract Copy Title: Assessing disease impacts of hatcheries on downstream salmonids in the Willamette River Basin, Oregon Author: Jakaitis, Michelle Hatcheries are often perceived as a source of pathogen amplification, potentially increasing disease risk to free-ranging populations; at the same time, free-ranging fishes may introduce pathogens into hatcheries through untreated water sources. Many pathogens exist naturally within the environment (with the exception of introduced pathogens) and the presence of a pathogen does not guarantee infection or disease (Naish, Taylor III, Levin, Quinn, Winton, Huppert & Hilborn 2007). Infections can be acute, chronic, or asymptomatic, fish may die, recover, or become carriers (Naish et al. 2007), and pathogens may be shed from any of these stages (Scottish Executive 2002). Most salmon and trout hatcheries along the Willamette River Basin, Oregon, USA, utilize an untreated river water supply for their rearing ponds and release this water, untreated, back into the river. This creates a potential for waterborne pathogens present in free-ranging hosts to be transmitted through the water supply to hatchery populations. Moreover, any hatchery epizootic can amplify pathogens and release these into the water, which could have a direct impact on free-ranging populations exposed to those pathogens in hatchery effluent. The goal of this thesis was to assess transmission of the pathogens Flavobacterium columnare, F. psychrophilum, Aeromonas salmonicida, Renibacterium salmonicida, and Infectious Hematopoietic Necrosis Virus (IHNV), at selected hatcheries in the Willamette River Basin. To accomplish this, I considered historical data and hatchery-specific and pathogen-specific factors involved in transmission and disease. Additionally, I conducted sentinel fishes exposures (Oncorhynchus mykiss and O. tshawytscha) at hatcheries during both epizootics and non-epizootic periods. Naïve sentinel fish were placed in hatchery influents and effluents to determine transmission direction and pathogen prevalence associated with hatcheries. I found that sentinel fishes developed infections downstream of hatcheries that were undergoing specific bacterial epizootics, or had low levels of pathogen prevalence within the hatchery, but not at any other time. Infections and mortality were due to the same pathogens responsible for hatchery epizootics, indicating the hatchery as a potential source. This may be a limited effect dependent on distance, dilution, and pathogen. The presence of large numbers of returning, congregating adult fishes may also contribute pathogens to the river in hatchery areas. Sentinel fishes held in hatchery influents did not, at any point, become infected with target pathogens, even during hatchery epizootics. Although I was unable to identify the pathogen entry point leading to hatchery epizootics, I determined that pathogen transmission appeared to be dependent on the pathogen, species, and location where sentinel fish were held. This thesis identifies routes and risks of pathogen transmission at selected Oregon hatcheries, with applications to inform state-wide fish health management. Title: Assessing disease impacts of hatcheries on downstream salmonids in the Willamette River Basin, Oregon Author: Jakaitis, Michelle Hatcheries are often perceived as a source of pathogen amplification, potentially increasing disease risk to free-ranging populations; at the same time, free-ranging fishes may introduce pathogens into hatcheries through untreated water sources. Many pathogens exist naturally within the environment (with the exception of introduced pathogens) and the presence of a pathogen does not guarantee infection or disease (Naish, Taylor III, Levin, Quinn, Winton, Huppert & Hilborn 2007). Infections can be acute, chronic, or asymptomatic, fish may die, recover, or become carriers (Naish et al. 2007), and pathogens may be shed from any of these stages (Scottish Executive 2002). Most salmon and trout hatcheries along the Willamette River Basin, Oregon, USA, utilize an untreated river water supply for their rearing ponds and release this water, untreated, back into the river. This creates a potential for waterborne pathogens present in free-ranging hosts to be transmitted through the water supply to hatchery populations. Moreover, any hatchery epizootic can amplify pathogens and release these into the water, which could have a direct impact on free-ranging populations exposed to those pathogens in hatchery effluent. The goal of this thesis was to assess transmission of the pathogens Flavobacterium columnare, F. psychrophilum, Aeromonas salmonicida, Renibacterium salmonicida, and Infectious Hematopoietic Necrosis Virus (IHNV), at selected hatcheries in the Willamette River Basin. To accomplish this, I considered historical data and hatchery-specific and pathogen-specific factors involved in transmission and disease. Additionally, I conducted sentinel fishes exposures (Oncorhynchus mykiss and O. tshawytscha) at hatcheries during both epizootics and non-epizootic periods. Naïve sentinel fish were placed in hatchery influents and effluents to determine transmission direction and pathogen prevalence associated with hatcheries. I found that sentinel fishes developed infections downstream of hatcheries that were undergoing specific bacterial epizootics, or had low levels of pathogen prevalence within the hatchery, but not at any other time. Infections and mortality were due to the same pathogens responsible for hatchery epizootics, indicating the hatchery as a potential source. This may be a limited effect dependent on distance, dilution, and pathogen. The presence of large numbers of returning, congregating adult fishes may also contribute pathogens to the river in hatchery areas. Sentinel fishes held in hatchery influents did not, at any point, become infected with target pathogens, even during hatchery epizootics. Although I was unable to identify the pathogen entry point leading to hatchery epizootics, I determined that pathogen transmission appeared to be dependent on the pathogen, species, and location where sentinel fish were held. This thesis identifies routes and risks of pathogen transmission at selected Oregon hatcheries, with applications to inform state-wide fish health management. Close

• 1130. [Article] Some effects of testosterone on cichlid fish, Cichlosoma bimaculatum (Linnaeus)

  The effects of testosterone were studied on the tropical fish, Cichlasoma bimaculatum. Growth experiments were designed to determine how testosterone influenced the food consumption and growth of fish. ...

  Citation × Citation Citation Abstract Copy Title: Some effects of testosterone on cichlid fish, Cichlosoma bimaculatum (Linnaeus) Author: Heitz, David Carl The effects of testosterone were studied on the tropical fish, Cichlasoma bimaculatum. Growth experiments were designed to determine how testosterone influenced the food consumption and growth of fish. Starvation experiments were designed to show the effects of testosterone on the basal rate of utilization of body energy stores and to establish what effect the anabolic steroid has when anabolism is reduced by the absence of metabolites from food. During the course of the experiments data were collected on wet weight, dry weight, fat, ash, protein and water content and on heat of combustion for control and testosterone treated fish. Four experiments were conducted where cichlids were starved, some as controls and some continuously exposed to testosterone 1:1,000,000. Wet weight, dry weight, weight of crude fat, weight of ash and the water content per cichlid usually decreased during starvation in controls and in the cichlids exposed to testosterone. Water content varied irregularly with reference to protein. Protein usually dropped where as water content dropped clearly in only one control experiment, did not alter markedly in two and increased in one. The testosterone treated fish tended to accumulate more water than did controls. Considerable variability was noted in the data. Much was due to an uneven distribution of cichlids with respect to weight among various groups and subgroups. Despite precautionary measures it was very difficult to maintain true starvation conditions. Some nonfilterable organic materials in the water as well as algae and minute insects may have been a source of food to the starving fish. More evident however, was the food made available as the result of the death of fish. On several occasions there was evidence of cannibalism, both in control and testosterone treated groups. The death of a fish, besides affording food to starving cichlids, introduced an error in the direction of increasing the average if a small fish died, and of decreasing the average if a Larger fish died. On the basis of calories disappearing during starvation, it was shown that starvation and starvation plus testosterone altered the composition of cichlids and decreased the heat of combustion per gram of cichlid. The testosterone treated fish were usually altered to a greater extent. Two growth studies were conducted where some cichlids were fed essentially ad libitum and utilized as controls, and others fed and continuously exposed to testosterone 1: 1, 000, 000. Dry weight in four out of six available comparisons was lower in testosterone treated fish than in controls; in one case the dry weights were similar and in one case the control cichlids had the higher dry weight. Protein was lower in five out of six available comparisons in the testosterone treated fish and were similar in one comparison. The control cichlids fed tubificids accumulated higher amounts of fat than cichlids fed and exposed to testosterone. The amount of food consumed per testosterone treated fish at each sample period was less than for the control fish. Starvation did not significantly alter the caloric equivalent per mg of dry matter. The caloric equivalent was higher in cichlids fed tubificid worms than in cichlids fed commercial fish food. Testosterone increased the caloric content per mg of nitrogen in the fish fed tubificid worms and this possibly indicates an anabolic action with formation of proteins with amino acids high in carbon and hydrogen and low in nitrogen and oxygen. During the fourth starvation experiment additional cichlids were used in order to investigate changes in lipids with starvation and testosterone as well as changes in fatty acid composition. There are some significant alterations in testosterone treated cichlid lipids beyond the alterations produced by starvation alone. The glycerides are reduced much more in the treated cichlids and also sooner. There was in general a reduction in fatty acids amounts in the treated fish. The greatest reduction in fatty acids occurred in fatty acids 16: 0, 16: 1, 18: 0, 18: 1 and 18: 2. Title: Some effects of testosterone on cichlid fish, Cichlosoma bimaculatum (Linnaeus) Author: Heitz, David Carl The effects of testosterone were studied on the tropical fish, Cichlasoma bimaculatum. Growth experiments were designed to determine how testosterone influenced the food consumption and growth of fish. Starvation experiments were designed to show the effects of testosterone on the basal rate of utilization of body energy stores and to establish what effect the anabolic steroid has when anabolism is reduced by the absence of metabolites from food. During the course of the experiments data were collected on wet weight, dry weight, fat, ash, protein and water content and on heat of combustion for control and testosterone treated fish. Four experiments were conducted where cichlids were starved, some as controls and some continuously exposed to testosterone 1:1,000,000. Wet weight, dry weight, weight of crude fat, weight of ash and the water content per cichlid usually decreased during starvation in controls and in the cichlids exposed to testosterone. Water content varied irregularly with reference to protein. Protein usually dropped where as water content dropped clearly in only one control experiment, did not alter markedly in two and increased in one. The testosterone treated fish tended to accumulate more water than did controls. Considerable variability was noted in the data. Much was due to an uneven distribution of cichlids with respect to weight among various groups and subgroups. Despite precautionary measures it was very difficult to maintain true starvation conditions. Some nonfilterable organic materials in the water as well as algae and minute insects may have been a source of food to the starving fish. More evident however, was the food made available as the result of the death of fish. On several occasions there was evidence of cannibalism, both in control and testosterone treated groups. The death of a fish, besides affording food to starving cichlids, introduced an error in the direction of increasing the average if a small fish died, and of decreasing the average if a Larger fish died. On the basis of calories disappearing during starvation, it was shown that starvation and starvation plus testosterone altered the composition of cichlids and decreased the heat of combustion per gram of cichlid. The testosterone treated fish were usually altered to a greater extent. Two growth studies were conducted where some cichlids were fed essentially ad libitum and utilized as controls, and others fed and continuously exposed to testosterone 1: 1, 000, 000. Dry weight in four out of six available comparisons was lower in testosterone treated fish than in controls; in one case the dry weights were similar and in one case the control cichlids had the higher dry weight. Protein was lower in five out of six available comparisons in the testosterone treated fish and were similar in one comparison. The control cichlids fed tubificids accumulated higher amounts of fat than cichlids fed and exposed to testosterone. The amount of food consumed per testosterone treated fish at each sample period was less than for the control fish. Starvation did not significantly alter the caloric equivalent per mg of dry matter. The caloric equivalent was higher in cichlids fed tubificid worms than in cichlids fed commercial fish food. Testosterone increased the caloric content per mg of nitrogen in the fish fed tubificid worms and this possibly indicates an anabolic action with formation of proteins with amino acids high in carbon and hydrogen and low in nitrogen and oxygen. During the fourth starvation experiment additional cichlids were used in order to investigate changes in lipids with starvation and testosterone as well as changes in fatty acid composition. There are some significant alterations in testosterone treated cichlid lipids beyond the alterations produced by starvation alone. The glycerides are reduced much more in the treated cichlids and also sooner. There was in general a reduction in fatty acids amounts in the treated fish. The greatest reduction in fatty acids occurred in fatty acids 16: 0, 16: 1, 18: 0, 18: 1 and 18: 2. Close