ACRDP Fact Sheets

Issue 14 - May 2012 The Effect of Photoperiod on Growth and Maturation of Atlantic Salmon (Salmo salar) in the Bay of Fundy	PDF (399 KB) HTML Show Summary
One of the main challenges to the long term sustainability of the Atlantic Salmon industry in Canada is the early sexual maturation of fish following their first winter in sea cages. Early maturation reduces growth rates of fish, affecting the size and quality of the final product, and as a result farmers incur significant financial loss (4-9% gross income). This research investigates the potential of artificially increasing day length (photoperiod) during the grow-out period of fish as a way to overcome early sexual maturity. In this study, two groups of immature farmed Atlantic Salmon were subjected to either 24-hour light from October/ November to May or natural light conditions (control group). Results showed that fish in 24-hour light conditions had almost a total suppression of early sexual maturation in both males and females and an increased growth rate compared to the fish in natural light conditions. Follow up experiments by the project researcher have confirmed these results, but also showed that manipulating day length can begin later, in December, with similar effective results. The lower operating costs for a shorter photomanipulation season combined with improved quality of the final product will help increase the profitability of the industry. This research provides a cost-effective tool that will directly improve the productivity and sustainability of the Canadian Atlantic Salmon aquaculture industry.

Issue 14 - May 2012
The Effect of Photoperiod on Growth and Maturation of Atlantic Salmon (Salmo salar) in the Bay of Fundy

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One of the main challenges to the long term sustainability of the Atlantic Salmon industry in Canada is the early sexual maturation of fish following their first winter in sea cages. Early maturation reduces growth rates of fish, affecting the size and quality of the final product, and as a result farmers incur significant financial loss (4-9% gross income). This research investigates the potential of artificially increasing day length (photoperiod) during the grow-out period of fish as a way to overcome early sexual maturity. In this study, two groups of immature farmed Atlantic Salmon were subjected to either 24-hour light from October/ November to May or natural light conditions (control group). Results showed that fish in 24-hour light conditions had almost a total suppression of early sexual maturation in both males and females and an increased growth rate compared to the fish in natural light conditions. Follow up experiments by the project researcher have confirmed these results, but also showed that manipulating day length can begin later, in December, with similar effective results. The lower operating costs for a shorter photomanipulation season combined with improved quality of the final product will help increase the profitability of the industry. This research provides a cost-effective tool that will directly improve the productivity and sustainability of the Canadian Atlantic Salmon aquaculture industry.

Issue 13 - May 2012 The Development of Cost-effective Diets and Husbandry Protocols for the Sustainable Aquaculture of Rockfish in British Columbia	PDF (175 KB) HTML Show Summary
Rockfish belong to the family Scorpaenidae (Sebastes spp.), and as a group have been identified as potential candidates for aquaculture. Sebastes species of the western Pacific are being cultured in both Korea and Japan. Considered a delicacy of Asian cuisine, rockfish have been the target of commercial and recreational fisheries. However, wild rockfish fisheries in the eastern Pacific have been in decline for years possibly due to the lucrative retail sale of live fish driving overfishing of these species. Populations of inshore rockfish are rapidly declining throughout coastal British Columbia. Conservation initiatives and fishery bans have been established to help restore depleted stocks of rockfish but this approach will require many years to be successful. However, a vibrant and active market for rockfish remains and alternative strategies are needed to fill these niches using an environmentally sustainable approach. This research project looks at the development of effective culture technology and husbandry protocols for sustainable rockfish aquaculture production in British Columbia to meet the high market demand for these fish without further depleting the natural stocks.

Issue 13 - May 2012
The Development of Cost-effective Diets and Husbandry Protocols for the Sustainable Aquaculture of Rockfish in British Columbia

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Rockfish belong to the family Scorpaenidae (Sebastes spp.), and as a group have been identified as potential candidates for aquaculture. Sebastes species of the western Pacific are being cultured in both Korea and Japan. Considered a delicacy of Asian cuisine, rockfish have been the target of commercial and recreational fisheries. However, wild rockfish fisheries in the eastern Pacific have been in decline for years possibly due to the lucrative retail sale of live fish driving overfishing of these species. Populations of inshore rockfish are rapidly declining throughout coastal British Columbia. Conservation initiatives and fishery bans have been established to help restore depleted stocks of rockfish but this approach will require many years to be successful. However, a vibrant and active market for rockfish remains and alternative strategies are needed to fill these niches using an environmentally sustainable approach. This research project looks at the development of effective culture technology and husbandry protocols for sustainable rockfish aquaculture production in British Columbia to meet the high market demand for these fish without further depleting the natural stocks.

Issue 12 - May 2012 Use of Genomics to Control Infectious Salmon Anemia Virus (ISAv)	PDF (302 KB) HTML Show Summary
Infectious Salmon Anemia virus (ISAv) poses a serious threat to fish farmers in Canada and globally. It can cause significant economic losses to Atlantic Salmon farming operations, and is a potential risk to wild Atlantic Salmon populations. Although improved farming and management practices have helped reduce the risk and impact of the disease, further outbreaks associated with new virulent strains remains a threat to the industry. A greater understanding of fish-virus interactions at the molecular level is of critical importance in the development of effective molecular tools and vaccines. A common approach for studying host-pathogen interactions at the molecular level is the use of functional genomic tools, such as DNA microarrays, which measure gene expression in specific tissues at specific times during the infection. With the use of this method, it has been possible to identify several genes up-regulated or down-regulated in salmon kidney tissue during the course of an ISAv infection and has provided a better understanding of how the fish fight the disease. Gene expression was measured at five different time points during an experimental infection: 6 hours, 24 h, 3 days, 7 d and 16 d after injection of the virus. Several genes involved in immune defense mechanisms were upregulated as the infection progressed. During the last stage of infection, several genes involved in oxygen transport were down-regulated. Such gene expression closely corresponds to anemia (low red blood cell count) observed in Atlantic Salmon infected by virulent strains of ISAv just prior to death. Such studies provide a deeper understanding of the defence mechanisms of fish against disease and provide insight into the approaches that could be taken to help the industry and prevent infections.

Issue 12 - May 2012
Use of Genomics to Control Infectious Salmon Anemia Virus (ISAv)

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Infectious Salmon Anemia virus (ISAv) poses a serious threat to fish farmers in Canada and globally. It can cause significant economic losses to Atlantic Salmon farming operations, and is a potential risk to wild Atlantic Salmon populations. Although improved farming and management practices have helped reduce the risk and impact of the disease, further outbreaks associated with new virulent strains remains a threat to the industry. A greater understanding of fish-virus interactions at the molecular level is of critical importance in the development of effective molecular tools and vaccines. A common approach for studying host-pathogen interactions at the molecular level is the use of functional genomic tools, such as DNA microarrays, which measure gene expression in specific tissues at specific times during the infection. With the use of this method, it has been possible to identify several genes up-regulated or down-regulated in salmon kidney tissue during the course of an ISAv infection and has provided a better understanding of how the fish fight the disease. Gene expression was measured at five different time points during an experimental infection: 6 hours, 24 h, 3 days, 7 d and 16 d after injection of the virus. Several genes involved in immune defense mechanisms were upregulated as the infection progressed. During the last stage of infection, several genes involved in oxygen transport were down-regulated. Such gene expression closely corresponds to anemia (low red blood cell count) observed in Atlantic Salmon infected by virulent strains of ISAv just prior to death. Such studies provide a deeper understanding of the defence mechanisms of fish against disease and provide insight into the approaches that could be taken to help the industry and prevent infections.

Issue 11 - May 2012 Pre-Commercial Integrated Multi-Trophic Aquaculture (IMTA) in Coastal British Columbia	PDF (302 KB) HTML Show Summary
Integrated Multi-Trophic Aquaculture (IMTA) is an aquaculture approach that employs a combination of economicallyviable aquaculture species to facilitate the interception, extraction, and use of waste components of a finfish farm. The goal of IMTA development is to create balanced systems for environmental remediation, economic stability, and social acceptability to support the sustainable development of aquaculture. Research on IMTA is on-going on both coasts of Canada to examine the commercial feasibility and to maximize the ecological benefits of the concept. At Kyuquot SEAfoods Ltd. in British Columbia a comprehensive research program is underway to apply this concept to culture operations. This project addressed three distinct technical issues crucial to the commercialization of the IMTA approach. First, the deposit-feeding sea cucumber (Parastichopus californicus), which naturally consumes organic material on the seabed, was shown to readily consume sablefish faeces and uneaten feed and exhibited good growth and survival rates on this waste material. Second, the development and testing of a unique shellfish production system, compatible with the finfish rearing infrastructure, demonstrated that this new grow-out system is a stable and highly productive platform for the production of multiple shellfish species. Third, the growth phase and overall productivity of the kelp component of the IMTA system was extended using an early, controlled stocking of kelp seed.

Issue 11 - May 2012
Pre-Commercial Integrated Multi-Trophic Aquaculture (IMTA) in Coastal British Columbia

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Integrated Multi-Trophic Aquaculture (IMTA) is an aquaculture approach that employs a combination of economicallyviable aquaculture species to facilitate the interception, extraction, and use of waste components of a finfish farm. The goal of IMTA development is to create balanced systems for environmental remediation, economic stability, and social acceptability to support the sustainable development of aquaculture. Research on IMTA is on-going on both coasts of Canada to examine the commercial feasibility and to maximize the ecological benefits of the concept. At Kyuquot SEAfoods Ltd. in British Columbia a comprehensive research program is underway to apply this concept to culture operations. This project addressed three distinct technical issues crucial to the commercialization of the IMTA approach. First, the deposit-feeding sea cucumber (Parastichopus californicus), which naturally consumes organic material on the seabed, was shown to readily consume sablefish faeces and uneaten feed and exhibited good growth and survival rates on this waste material. Second, the development and testing of a unique shellfish production system, compatible with the finfish rearing infrastructure, demonstrated that this new grow-out system is a stable and highly productive platform for the production of multiple shellfish species. Third, the growth phase and overall productivity of the kelp component of the IMTA system was extended using an early, controlled stocking of kelp seed.

Issue 10 - May 2012 Mussel Seed Quality and Availability in Newfoundland	PDF (531 KB) HTML Show Summary
The rapidly-growing mussel industry in Newfoundland requires new spat collection sites from areas close to their growout sites. This would provide backup for seed collection, allow for better growth performance as the young mussels become acclimated to the environmental conditions closer to the growout sites, and reduce seed transport costs. Species composition and potential sites for mussel culture were evaluated in a multi-year study. The objective was to identify several mussel seed collection sites in the Placentia and Bonavista Bay regions of Newfoundland. Following a 2-year time series experiment, it was determined that preferential seed collection of two blue mussel species commonly found in the coastal waters of Newfoundland, Mytilus edulis and Mytilus trossulus, was not significantly affected by the set depth or timing of collection (eastern Notre Dame Bay). However, for the Placentia Bay site, numbers of M. trossulus and hybrids of the two species increased over the summer. This suggested that to collect M. edulis, spat collections must be made earlier in the year. Seed transfer trials were initiated based on data obtained from this study. The results of this study contribute toward the process of locating alternate seed collection sites to foster sustainable development of the mussel aquaculture industry in Newfoundland.

Issue 10 - May 2012
Mussel Seed Quality and Availability in Newfoundland

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The rapidly-growing mussel industry in Newfoundland requires new spat collection sites from areas close to their growout sites. This would provide backup for seed collection, allow for better growth performance as the young mussels become acclimated to the environmental conditions closer to the growout sites, and reduce seed transport costs. Species composition and potential sites for mussel culture were evaluated in a multi-year study. The objective was to identify several mussel seed collection sites in the Placentia and Bonavista Bay regions of Newfoundland. Following a 2-year time series experiment, it was determined that preferential seed collection of two blue mussel species commonly found in the coastal waters of Newfoundland, Mytilus edulis and Mytilus trossulus, was not significantly affected by the set depth or timing of collection (eastern Notre Dame Bay). However, for the Placentia Bay site, numbers of M. trossulus and hybrids of the two species increased over the summer. This suggested that to collect M. edulis, spat collections must be made earlier in the year. Seed transfer trials were initiated based on data obtained from this study. The results of this study contribute toward the process of locating alternate seed collection sites to foster sustainable development of the mussel aquaculture industry in Newfoundland.

Issue 9 - January 2011 The Cod Broodstock Nutrition Study	PDF (332 KB) HTML Show Summary
Good nutrition is fundamental for raising healthy broodstock and for the production of high quality gametes. Previous work in Atlantic Canada has led to the development of a standard diet made of wild fish (herring, mackerel, and squid) with vitamin supplementation. However, a wild fish diet has numerous drawbacks including, inconsistent supply, unpredictable quality, prohibitive costs, and high risk for disease transfer. This project will determine the influence of diets on the spawning and growth of first generation photomanipulated cod broodstock. These diets include 1) a commercial on-growing pellet, 2) an experimental manufactured pellet (marine finfish broodstock formulation), and 3) the current standard diet of wild fish, supplemented with vitamins. This study will enhance our understanding of the nutritional requirements of cod broodstock, in order to improve reproductive performance in support of the long-term sustainability of cod culture in Canada. Results show that a commercial on-growing diet is inadequate for young broodstock and that the broodstock experimental diet may contribute to an improvement of the reproductive performance over the on-growing diet.

Issue 9 - January 2011
The Cod Broodstock Nutrition Study

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Good nutrition is fundamental for raising healthy broodstock and for the production of high quality gametes. Previous work in Atlantic Canada has led to the development of a standard diet made of wild fish (herring, mackerel, and squid) with vitamin supplementation. However, a wild fish diet has numerous drawbacks including, inconsistent supply, unpredictable quality, prohibitive costs, and high risk for disease transfer. This project will determine the influence of diets on the spawning and growth of first generation photomanipulated cod broodstock. These diets include 1) a commercial on-growing pellet, 2) an experimental manufactured pellet (marine finfish broodstock formulation), and 3) the current standard diet of wild fish, supplemented with vitamins. This study will enhance our understanding of the nutritional requirements of cod broodstock, in order to improve reproductive performance in support of the long-term sustainability of cod culture in Canada. Results show that a commercial on-growing diet is inadequate for young broodstock and that the broodstock experimental diet may contribute to an improvement of the reproductive performance over the on-growing diet.

Issue 8 - October 2010 Commercial, Environmental and Physiological Performance of Brook Trout Fed with Low-Phosphorus, High-Energy Feeds	PDF (358 KB) HTML Show Summary
Over the past two decades, improvements in the nutritional quality of the feeds used for salmonid production have made possible a very significant reduction in solid waste, phosphorus and nitrogen discharges and, ultimately, feed costs. At the same time, it has been suggested that the new, high-lipid feeds that have been developed could have negative impacts on the production of brook trout (Salvelinus fontinalis). The present study was carried out to verify the effect of lipid content in feed as well as the effect of certain lower-phosphorus replacement meals on the physiology of this species. The study's main conclusions show that: 1) the substitution of poultry by-product meal for fishmeal at a rate of 50% could yield a slight improvement in biological and environmental performance; 2) soy protein concentrate is not an advantageous protein source for replacing fishmeal; and 3) a feed low in lipids (18% based on feed formulation) seemed to yield slightly higher biological and environmental performance compared to a control feed that was higher in lipids (24% based on feed formulation). However, further basic biochemical and physiological research would be required to gain a good understanding of the specific qualities and different physiological stages of brook trout, with the ultimate goal of improving fish farm yields while reducing environmental impacts.

Issue 8 - October 2010
Commercial, Environmental and Physiological Performance of Brook Trout Fed with Low-Phosphorus, High-Energy Feeds

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Over the past two decades, improvements in the nutritional quality of the feeds used for salmonid production have made possible a very significant reduction in solid waste, phosphorus and nitrogen discharges and, ultimately, feed costs. At the same time, it has been suggested that the new, high-lipid feeds that have been developed could have negative impacts on the production of brook trout (Salvelinus fontinalis). The present study was carried out to verify the effect of lipid content in feed as well as the effect of certain lower-phosphorus replacement meals on the physiology of this species. The study's main conclusions show that: 1) the substitution of poultry by-product meal for fishmeal at a rate of 50% could yield a slight improvement in biological and environmental performance; 2) soy protein concentrate is not an advantageous protein source for replacing fishmeal; and 3) a feed low in lipids (18% based on feed formulation) seemed to yield slightly higher biological and environmental performance compared to a control feed that was higher in lipids (24% based on feed formulation). However, further basic biochemical and physiological research would be required to gain a good understanding of the specific qualities and different physiological stages of brook trout, with the ultimate goal of improving fish farm yields while reducing environmental impacts.

Issue 7 - May 2010 Cadmium in Deepwater-Cultured Pacific Oysters	PDF (1.01 MB) HTML Show Summary
British Columbia (BC) shellfish growers are interested in expanding their sales in international markets, which would increase demand for their products and allow the industry to further mature. However, in the past, concentrations of the toxic metal cadmium (Cd) in BC Pacific oysters (Crassostrea gigas) (at times exceeding the importing country's standards) have limited this opportunity. The allowable limit of Cd in bivalve molluscs for export varies between 1.0 and 3.7 μg g-1 wet weight, depending on the importing country. The presence of Cd in shellfish poses a significant challenge to the BC shellfish export trade, as certain human activities and natural coastal geology affect Cd levels in the environment and, ultimately, the animals. This research sought to determine the variables that affect the accumulation of Cd in BC cultured oysters. The results of the project will help growers understand, and potentially mitigate, high levels of Cd in their shellfish, thereby contributing to the long-term sustainability of oyster culture in British Columbia.

Issue 7 - May 2010
Cadmium in Deepwater-Cultured Pacific Oysters

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British Columbia (BC) shellfish growers are interested in expanding their sales in international markets, which would increase demand for their products and allow the industry to further mature. However, in the past, concentrations of the toxic metal cadmium (Cd) in BC Pacific oysters (Crassostrea gigas) (at times exceeding the importing country's standards) have limited this opportunity. The allowable limit of Cd in bivalve molluscs for export varies between 1.0 and 3.7 μg g-1 wet weight, depending on the importing country. The presence of Cd in shellfish poses a significant challenge to the BC shellfish export trade, as certain human activities and natural coastal geology affect Cd levels in the environment and, ultimately, the animals. This research sought to determine the variables that affect the accumulation of Cd in BC cultured oysters. The results of the project will help growers understand, and potentially mitigate, high levels of Cd in their shellfish, thereby contributing to the long-term sustainability of oyster culture in British Columbia.

Issue 6 - May 2010 Containment and Mitigation of Nuisance Tunicates on Prince Edward Island to Improve Mussel Farm Productivity	PDF (0.97 MB) HTML Show Summary
The mussel aquaculture industry in Prince Edward Island has been severely impacted by the introduction of four invasive tunicate species since 1998. Two solitary tunicates, the clubbed (Styela clava) and vase (Ciona intestinalis) tunicates, and two colonial tunicates, the violet (Botrylloides violaceus) and golden star (Botryllus schlosseri) tunicates, are challenging the sustainability and productivity of this vital industry. Initial efforts were directed toward controlling the spread of these tunicates. Recently, to ensure sustainability of the PEI mussel industry, efforts have been focused on mitigation measures to reduce the impact of tunicate infestation on mussel farms.

Issue 6 - May 2010
Containment and Mitigation of Nuisance Tunicates on Prince Edward Island to Improve Mussel Farm Productivity

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The mussel aquaculture industry in Prince Edward Island has been severely impacted by the introduction of four invasive tunicate species since 1998. Two solitary tunicates, the clubbed (Styela clava) and vase (Ciona intestinalis) tunicates, and two colonial tunicates, the violet (Botrylloides violaceus) and golden star (Botryllus schlosseri) tunicates, are challenging the sustainability and productivity of this vital industry. Initial efforts were directed toward controlling the spread of these tunicates. Recently, to ensure sustainability of the PEI mussel industry, efforts have been focused on mitigation measures to reduce the impact of tunicate infestation on mussel farms.

Issue 5 - May 2010 Evaluation of suspension culture methods for Giant Scallops (Placopecten magellanicus) in the Magdalen Islands, Quebec	PDF (722 KB) HTML Show Summary
This study, conducted from 2001 to 2004 at three lagoon sites in the Magdalen Islands, examined sea scallop survival, losses and growth in suspension culture using five different culture methods: ear-hanging, pocket net, pearl net, oyster table, and Wang-Joncas lantern. The effect of cleaning fouling organisms off of the structures was also assessed. Although highly variable, the results show a significant effect of the site and type of structure used on scallop survival. The data from the 2001 trial showed that scallop losses were greater in the pocket nets and Wang-Joncas lantern structures than in the pearl nets and oyster tables. Cleaning of the structures had a variable effect and no real trend was noted. Overall, the scallops obtained from the ear-hanging system and from pocket nets reached the largest sizes. Collectively, the technical and biological results appear to show that these two culture structures are the best suited to the lagoons in the Magdalen Islands. The performance of scallops grown in these structures could be enhanced through cleaning done at appropriate times to reduce the effect of mussels on the ear-hanging system and through the modification of the openings of pocket nets to minimize scallop losses.

Issue 5 - May 2010
Evaluation of suspension culture methods for Giant Scallops (Placopecten magellanicus) in the Magdalen Islands, Quebec

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This study, conducted from 2001 to 2004 at three lagoon sites in the Magdalen Islands, examined sea scallop survival, losses and growth in suspension culture using five different culture methods: ear-hanging, pocket net, pearl net, oyster table, and Wang-Joncas lantern. The effect of cleaning fouling organisms off of the structures was also assessed.

Although highly variable, the results show a significant effect of the site and type of structure used on scallop survival. The data from the 2001 trial showed that scallop losses were greater in the pocket nets and Wang-Joncas lantern structures than in the pearl nets and oyster tables. Cleaning of the structures had a variable effect and no real trend was noted. Overall, the scallops obtained from the ear-hanging system and from pocket nets reached the largest sizes. Collectively, the technical and biological results appear to show that these two culture structures are the best suited to the lagoons in the Magdalen Islands. The performance of scallops grown in these structures could be enhanced through cleaning done at appropriate times to reduce the effect of mussels on the ear-hanging system and through the modification of the openings of pocket nets to minimize scallop losses.

Issue 4 - April 2010 Does Microbubble Aeration Reduce Potential Oyster Microbial Contaminants in Seawater?	PDF (237 KB) HTML Show Summary
Oysters should be grown in waters containing minimal numbers of microbes which may be potentially pathogenic to the oysters or, from a food safety point of view, to the humans that consume them. Influxes of birds or marine mammals that occupy rafts or floats at a shellfish farm, may lead to increased fecal material in the water and an accumulation of fecal coliforms and other human pathogens in the shellfish. Contaminations that result in farm closures or harm to humans can cause serious damage to the business and reputation of the shellfish industry. Therefore, a cost-effective method of decreasing fecal source bacterial and other microbes in seawater would be extremely beneficial for shellfish and other aquaculture-based industries. This project examined whether microbubblers can reduce microbial contaminants in seawater. Experiments were conducted to evaluate the survival of various bacteria in seawater in the presence and absence of different microbubblers and aeration devices. Contrary to the indications of previous observations, microbubblers did not directly affect the survivability of selected potential microbial contaminants of oysters. Decreases in bacterial counts were found in tested waters when a microbubbler aeration device containing some metallic parts was used. An accumulation of copper leaching from the metal parts in the device, as opposed to the production of micro-bubbles by the device, could explain the rapid decline of bacteria seen in laboratory tests.

Issue 4 - April 2010
Does Microbubble Aeration Reduce Potential Oyster Microbial Contaminants in Seawater?

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Oysters should be grown in waters containing minimal numbers of microbes which may be potentially pathogenic to the oysters or, from a food safety point of view, to the humans that consume them. Influxes of birds or marine mammals that occupy rafts or floats at a shellfish farm, may lead to increased fecal material in the water and an accumulation of fecal coliforms and other human pathogens in the shellfish. Contaminations that result in farm closures or harm to humans can cause serious damage to the business and reputation of the shellfish industry. Therefore, a cost-effective method of decreasing fecal source bacterial and other microbes in seawater would be extremely beneficial for shellfish and other aquaculture-based industries. This project examined whether microbubblers can reduce microbial contaminants in seawater.

Experiments were conducted to evaluate the survival of various bacteria in seawater in the presence and absence of different microbubblers and aeration devices. Contrary to the indications of previous observations, microbubblers did not directly affect the survivability of selected potential microbial contaminants of oysters. Decreases in bacterial counts were found in tested waters when a microbubbler aeration device containing some metallic parts was used. An accumulation of copper leaching from the metal parts in the device, as opposed to the production of micro-bubbles by the device, could explain the rapid decline of bacteria seen in laboratory tests.

Issue 3 - April 2009 Production of All-Female Populations of Coho Salmon, Oncorhynchus kisutch, using Y-Chromosomal DNA Markers	PDF (250 KB) HTML Show Summary
Some strains of coho salmon show moderate to high levels of early sexual maturation, at a sub-optimal market size. Development of all-female strains of this species could be of significant benefit for the aquaculture industry, by eliminating losses arising from early maturation of males, and allowing for a doubling in roe production from the same number of production animals as in mixed sex cultures. Single sex populations also provide an environmental benefit in areas where non-native species are being cultured, by providing a highly effective method for reproductive containment. Application of simple PCR-based diagnostics can allowregular XY males to be distinguished from masculinized XX males, facilitating the development and maintenance of monosex, all-female strains.

Issue 3 - April 2009
Production of All-Female Populations of Coho Salmon, Oncorhynchus kisutch, using Y-Chromosomal DNA Markers

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Some strains of coho salmon show moderate to high levels of early sexual maturation, at a sub-optimal market size. Development of all-female strains of this species could be of significant benefit for the aquaculture industry, by eliminating losses arising from early maturation of males, and allowing for a doubling in roe production from the same number of production animals as in mixed sex cultures. Single sex populations also provide an environmental benefit in areas where non-native species are being cultured, by providing a highly effective method for reproductive containment.

Application of simple PCR-based diagnostics can allowregular XY males to be distinguished from masculinized XX males, facilitating the development and maintenance of monosex, all-female strains.

Issue 2 - April 2009 Optimal Net Depth for Over-Wintering Bay d'Espoir, Newfoundland and Labrador, Aquaculture Salmonids	PDF (980 KB) HTML Show Summary
Bay d'Espoir, a main production area for the Newfoundland salmonid aquaculture industry on the south coast of the island, faces challenges associated with fish production in an extremely cold winter environment. In this region, surface freezing, under-ice culture and sub-lethal temperatures are common occurrences. The former Newfoundland Salmonid Growers Association (NSGA) sought to identify the necessary net depth for optimal salmonid aquaculture performance during winter periods. This study showed that the use of nets significantly deeper than 10 m for over-wintering of salmonids in high current areas in Bay d'Espoir may not be economically justifiable through increased growth or survival of 1st-year salmonids, however, net depths of up to 15 m may be useful for improving the economic performance of 2nd-year salmonids by increasing the likelihood of survival.

Issue 2 - April 2009
Optimal Net Depth for Over-Wintering Bay d'Espoir, Newfoundland and Labrador, Aquaculture Salmonids

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Bay d'Espoir, a main production area for the Newfoundland salmonid aquaculture industry on the south coast of the island, faces challenges associated with fish production in an extremely cold winter environment. In this region, surface freezing, under-ice culture and sub-lethal temperatures are common occurrences. The former Newfoundland Salmonid Growers Association (NSGA) sought to identify the necessary net depth for optimal salmonid aquaculture performance during winter periods. This study showed that the use of nets significantly deeper than 10 m for over-wintering of salmonids in high current areas in Bay d'Espoir may not be economically justifiable through increased growth or survival of 1st-year salmonids, however, net depths of up to 15 m may be useful for improving the economic performance of 2nd-year salmonids by increasing the likelihood of survival.

Issue 1 - April 2009 Use of High-Quality Trout Feeds to Improve Growth Performance and Decrease Phosphorus Waste	PDF (1.07 MB) HTML Show Summary
When trout are fed with high energy / low phosphorus feed, it is possible to obtain a reduction in food conversion rate and phosphorus waste. Although new Canadian feeds are higher in price, the improved feed conversion ratios afford an overall reduced cost of feeding fish per unit of gain, while also reducing the total phosphorus discharge. Based on these studies, the utilisation of high-performance feeds by Canadian trout growers is recommended.

Issue 1 - April 2009
Use of High-Quality Trout Feeds to Improve Growth Performance and Decrease Phosphorus Waste

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When trout are fed with high energy / low phosphorus feed, it is possible to obtain a reduction in food conversion rate and phosphorus waste. Although new Canadian feeds are higher in price, the improved feed conversion ratios afford an overall reduced cost of feeding fish per unit of gain, while also reducing the total phosphorus discharge. Based on these studies, the utilisation of high-performance feeds by Canadian trout growers is recommended.