ACRDP Fact Sheets

Issue 22 - December 2013
Ecological effects of blue LED lights used at marine finfish aquaculture sites in British Columbia

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The use of artificial lighting within finfish aquaculture operations is a common technique used to delay sexual maturation and produce larger fish. Currently, finfish growers in British Columbia are interested in exploring the use of blue light emitting diode (LED) lights. These blue LED lights are more efficient, use less energy and last longer than the traditionally used white metal halide lights, making them an attractive, economical choice. However, artificial lighting may affect both the diversity and abundance of the native organisms surrounding an aquaculture site, and this study evaluated these potential effects. The use of blue LED lights at an experimental site at night was found to attract fish and zooplankton, when compared to unlit controls. No statistical difference was observed for phytoplankton abundance (in the absence of blooms) or the settlement of benthic invertebrates between blue LED lights and controls. A commercial finfish site was also equipped with blue LED lights to determine their effects on fish maturation, growth and sea lice counts in comparison to a site equipped with traditional white halide lights. There was no statistical difference in sea lice counts between farm sites equipped with blue LED lights or white halide lights, but direct comparisons were difficult. The results of this project have led to an increased understanding of the effects of blue LED lights on the native biota, but continued research is necessary in order to determine the effects and implications of blue LED lights directly at an aquaculture site. This information will allow both industry and Fisheries and Oceans Canada (DFO) to continue to support the sustainable development of finfish operations in British Columbia, and better manage the intricate relationship between aquaculture and the environment.

Issue 21 - December 2013
Depletion of emamectin benzoate (SLICE®) from skeletal muscle and skin tissues of Atlantic Salmon (Salmo salar)

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Atlantic Salmon aquaculture operations require a method of controlling infestations of the parasitic sea lice (Lepeophtheirus salmonis). One means of controlling sea lice infestation is SLICE® (emamectin benzoate (EMB)), a synthetically derived compound delivered orally in feed and absorbed from the gut into tissues. Health Canada (HC) and the Canadian Food Inspection Agency (CFIA) have set guidelines for the use of this product including a Maximum Residue Limit (MRL) and a withdrawal period. However, these guidelines were considered stringent in comparison to other national jurisdictions and placed restrictions on planned and emergency harvesting operations for producers that resulted in unnecessary marketing barriers. To study the depletion rate of EMB in comparison to set withdrawal times, this project investigated the rate of depletion of SLICE® residues in the tissues of Atlantic Salmon (Salmo salar) in both controlled laboratory and commercial settings. Laboratory and field operations monitored an administration of SLICE® at a dose rate of 50 micrograms per kilogram (μg / kg) body weight per day for 7 consecutive days. The depletion of the compound from tissues was monitored at intervals from 1 to 45 days post treatment. Mean EMB residues in laboratory samples ranged from 7.3 to 60.5 nanograms per gram (ng / g) in muscle tissue and 28.1 to 199.7 ng / g in skin tissue. MRL levels allowed by HC and CFIA were 100 and 1000 ng / g, in muscle and skin tissue respectively at the time of this study. MRLs at this level were not detected in the field or laboratory results indicating that actual residue levels of EMB did not exceed the set limits. Results from this project were fundamental to the 2009 full approval and registration of SLICE® by HC, which included amending the withdrawal period to 0 days.

Issue 20 - November 2013
Determining optimal culture periods for the Atlantic Kelp (Saccharina longicruris) in Gaspésie, Quebec

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Commercial culture of marine seaweeds in Quebec is in the very early stages of development. Initial trials to culture algae began in the autumn of 2005 by Les Gaspésiennes–Algues Inc. The company was active in processing marine algae for various purposes and wanted more control over the quantity, quality and regularity of its supply. Initial trials of macroalgae culture focused on Saccharina longicruris and were conducted in 2006 and 2007 in Chaleur Bay in a production cycle lasting from April to November. During initial trials, major biomass losses were observed after the fronds were colonized by the bryozoan Membranipora membranacea, a non-native invasive species. This study investigated the possibility of reducing bryozoan-related losses by beginning the production cycle earlier in the year in order to avoid culturing during the summer, when the bryozoan has been known to establish on fronds. Concurrently, the study also tested a four month production cycle, so that three production cycles could be established per year (autumn, winter, and spring). Results indicated that short cycles do not produce sufficient harvest volume. However, transferring plantlets (young algal plants) to sea in late autumn and harvesting them in July of the following year (8- to 10-month Autumn-Summer production cycle) resulted in good harvest of the cultured algae in good condition and free of bryozoans.

Issue 19 - November 2013
Saltwater Rearing of Endangered Inner Bay of Fundy Atlantic Salmon Smolt: A Comparison with Standard Freshwater Techniques

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As part of the inner Bay of Fundy (iBoF) conservation efforts for wild Atlantic Salmon, this Aquaculture Collaborative Research and Development Program (ACRDP) project explored a novel, naturalized saltwater rearing technique to determine the effect of saltwater rearing on adult return rates and offspring viability. Wild iBoF Atlantic Salmon smolts were collected and reared to adults in either marine net pens (pens set up in the natural environment at a salmon farm) or a land-based freshwater hatchery. A sub-sample of adult salmon were retained for spawning experiments to determine the effect of rearing technique on offspring viability. In 2011, 43 of the adult salmon released into the Bay of Fundy were observed to return to the freshwater environment. The majority of these fish were net pen-reared individuals. In 2012, similar returning numbers were observed with the majority of the sampled returns also being from the net pen-reared group released to sea in 2011. Taking into account all known releases of salmon, the net pen-reared fish returned approximately 2:1 compared to hatchery-reared fish. The five-month survival rates of offspring were 62% from net pen-reared parents and 48% from hatchery parents, suggesting that a more naturalized rearing environment may also improve offspring survival. Results from this project have elicited widespread interest from other conservation groups and the aquaculture industry in continuing to test this theory and replicate these successes for salmon conservation elsewhere in Atlantic Canada.

Issue 18 - March 2013
Mechanized Clam Harvesting for Coastal British Columbia: An Assessment of Potential Environmental Implications

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The mechanization of the British Columbia (BC) shellfish aquaculture industry is one means of increasing its competitiveness within the global shellfish market. Currently, the traditional hand rake is the primary method of harvesting shellfish. This is a labour-intensive activity yielding medium production levels. A mechanical harvester has the potential to greatly reduce harvesting costs and increase production output. To determine the feasibility and potential benthic impacts of using a mechanical harvester, a comparative environmental assessment and operational performance of both mechanical and manual (i.e. hand rake) harvesting techniques were undertaken. In July 2008, assessments were conducted at three study sites in Baynes Sound, BC. Each of the three sites contained a mechanical and manual harvest plot. Sampling stations were at fixed positions at varying distances (0, 1, 25, 50, and 75 m) from each plot along transects following the dominant current direction. Surveys were conducted both pre- and post-harvest. Parameters measured included in situ sediment sulphide concentrations, redox (or reduction-oxidation) potential, sediment grain size, visual condition of substrate through digital imagery, sedimentation (silt flux) and sediment macro-faunal composition. Generally, no major differences were observed between the effects of both harvest methods. Sulphide, redox potential and sedimentation sampling showed high variability within treatment plots and transects, within all samples for each beach, and between mean samples for each beach. Due to high levels of variance observed in all parameters measured, definite conclusions cannot be made about significant differences in environmental effects between the harvesting methods. Despite the variability in results, it was observed that sedimentation from both mechanical and manual harvesting was negligible in comparison to the massive sediment flux occurring during natural processes (e.g., storm events).

Issue 17 - March 2013
Signal Crayfish: Improving Culture Techniques and Diets in British Columbia

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Signal Crayfish (Pacifastacus leniusculus) are thought to be a species of commercial production potential, however there are a number of culture techniques that need to be better refined before commercial production is viable in Canada. This project sought to establish culture techniques for the species, by assessing growth and survival of juveniles as well as the digestive capabilities of adult crayfish fed formulated diets containing sustainable feed ingredients. The sustainable ingredients chosen were soybean meal, a common feed substitute for fishmeal, and Duckweed (Spirodela polyrrhiza), an invasive freshwater plant species, in British Columbia. During this project, Signal Crayfish were successfully raised for an entire year with minimal mortalities. Each of the diets tested showed very good survival and similar levels of growth. Crayfish consumed higher proportions of the Duckweed diet despite a slightly lower digestibility which suggests that aquatic macrophytes may be important feed ingredients for increasing palatability and caloric intake. This work provided a key first step in the culture of Signal Crayfish in British Columbia, and has shown that it is possible to breed and rear Signal Crayfish in captivity.

Issue 16 - March 2013
Basket Cockle (Clinocardium nuttallii): Candidate Commercial Aquaculture Species in British Columbia

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The Aquaculture Collaborative Research and Development Program (ACRDP) has funded three research projects, with Evening Cove Oysters Ltd., focusing on various hatchery, nursery and grow-out aspects of the development of Basket Cockle (Clinocardium nuttallii) aquaculture in British Columbia (BC). There is a great desire to move this species toward commercialization for both the diversification of the aquaculture industry in Canada, as well as for the creation of much needed jobs in coastal and First Nations communities. The Basket Cockle is native to BC and although commonly found on the shore, it is generally present in low abundances. They are a culturally-significant species for coastal Aboriginal peoples in BC and interest has been expressed by some First Nation communities in commercializing the species in their territories. Advances in hatchery and out-planting research have moved this species one step closer to commercialization. The outcomes and recommendations of these projects have been documented in various publications and should be referred to for a complete account of methodologies and results for the various projects. The following provides a general summary of the research to date.

Issue 15 - March 2013
Potential Benthic Impacts of Pacific Geoduck (Panopea generosa) Aquaculture in British Columbia

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The Pacific Geoduck (Panopea generosa) fishery is the most valuable dive fishery in British Columbia (BC). Significant interest from both wild harvesters and aquaculturists in the enhancement (of the wild stock) and culture of the species has been demonstrated, however, the expansion of the BC culture industry in intertidal and subtidal environments has been hindered in part by concerns over the potential benthic impacts of culture and harvest practices. Two projects on Pacific Geoduck aquaculture funded by the Aquaculture Collaborative Research and Development Program (ACRDP) have been conducted to examine the potential impacts of intertidal and subtidal geoduck culture and harvesting on the benthic environment. Results from both projects have demonstrated that the benthic impacts of small-scale geoduck out-planting and small- to large-scale harvesting in the experimental plots were relatively minor and limited in duration and/or spatial extent.

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

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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)

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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

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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

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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

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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

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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

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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

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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

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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?

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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

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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

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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

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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.