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Shrimpton J.M.,University of Northern British Columbia | Heath J.W.,Yellow Island Aquaculture Ltd. | Devlin R.H.,Center for Aquaculture and Environmental Research | Heath D.D.,University of Windsor
Aquaculture | Year: 2012

The use of triploid salmon for aquaculture is attractive as they do not mature sexually, limiting losses associated with poor flesh quality in mature fish and posing less genetic risk to wild stocks if they escape. Inconsistent survival and growth performance in triploid fish, however, has limited their implementation. In our study, ocean-type Chinook salmon (Oncorhynchus tshawytscha) were bred using replicated 3×3 factorial mating designs to create 18 families to test whether triploidization resulted in changes in growth and ionoregulation performance in freshwater and seawater. Eggs were pressure shocked after fertilization to create triploid offspring in a subset of each family. In spring, freshwater fish were sampled for size and gill Na +, K +-ATPase activity. Plasma chloride and cortisol were measured following a 24-h saltwater challenge. Growth performance was monitored for a further four months following transfer to sea water. We found significant effects of ploidy and sire (paternal effect) on smolt weight, as well as on gill Na +, K +-ATPase activity, although the latter did not correspond with performance in a 24-h saltwater challenge. Following four months of ocean growth, diploid animals were consistently larger, with greater circulating levels of insulin-like growth factor-1 than triploid sibs, although specific growth rates did not differ. Conversely, gill Na +, K +-ATPase activity at that time was significantly higher in triploid than diploid fish. When the phenotypic variance for the various traits was partitioned, triploids exhibited significantly greater additive genetic variance and maternal effects across all traits relative to diploid fish - indicating that gene dosage effects were primarily additive. The strong family effect indicates that genotype has a substantial role in determining the effects of ploidy manipulation on ionoregulatory and growth performance in Chinook salmon. © 2011 Elsevier B.V.

Briski E.,Canadian Department of Fisheries and Oceans | Bailey S.A.,Canadian Department of Fisheries and Oceans | Casas-Monroy O.,Bedford Institute of Oceanography | DiBacco C.,Bedford Institute of Oceanography | And 14 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2012

Increasing empirical evidence indicates the number of released individuals (i.e. propagule pressure) and number of released species (i.e. colonization pressure) are key determinants of the number of species that successfully invade new habitats. In view of these relationships, and the possibility that ships transport whole communities of organisms, we collected 333 ballast water and sediment samples to investigate the relationship between propagule and colonization pressure for a variety of diverse taxonomic groups (diatoms, dinoflagellates and invertebrates). We also reviewed the scientific literature to compare the number of species transported by ships to those reported in nature. Here, we show that even though ships transport nearly entire local communities, a strong relationship between propagule and colonization pressure exists only for dinoflagellates. Our study provides evidence that colonization pressure of invertebrates and diatoms may fluctuate widely irrespective of propagule pressure. We suggest that the lack of correspondence is explained by reduced uptake of invertebrates into the transport vector and the sensitivity of invertebrates and diatoms to selective pressures during transportation. Selection during transportation is initially evident through decreases in propagule pressure, followed by decreased colonization pressure in the most sensitive taxa. © 2012 The Royal Society.

Callan C.K.,The Oceanic Institute | Laidley C.W.,The Oceanic Institute | Forster I.P.,The Oceanic Institute | Forster I.P.,Center for Aquaculture and Environmental Research | And 3 more authors.
Aquaculture Research | Year: 2012

This study was conducted to determine the effects of broodstock diet on flame angelfish (Centropyge loriculus) reproduction and generate baseline spawning performance (mean fecundity, egg fertilization, egg viability) and egg biochemistry data for this species. Sixteen flame angelfish broodstock pairs were maintained on one of three formulated diets or a raw diet (consisting of squid, shrimp, fish eggs and algae) to determine the effect of diet composition on the fecundity, egg fertilization rates and egg viability over a 7-month period. Although all the diets supported similar mean spawn frequency and fecundity over the duration of the experiment, the mean fertilization rates and egg viability were significantly greater among pairs receiving the raw diet. Egg fatty acid composition was generally reflective of the maternal diet and similar to the values reported for other tropical species. In particular, dietary factors such as n-3 highly unsaturated fatty acid and ARA level (which were elevated in the raw diet and eggs from fish receiving that treatment) are correlated with egg quality and are therefore worthy of future investigation. Because of the ease of conditioning, adaptability to varied formulated diets and continuous, sustained reproductive output, flame angelfish are an excellent model for examining the factors affecting marine fish egg and larval quality. © 2011 Blackwell Publishing Ltd.

Vandersteen W.,Center for Aquaculture and Environmental Research | Biro P.,Deakin University | Harris L.,Center for Aquaculture and Environmental Research | Harris L.,Canadian Department of Fisheries and Oceans | Devlin R.,Center for Aquaculture and Environmental Research
Evolutionary Applications | Year: 2012

We tested the fitness consequences of introgression of fast-growing domesticated fish into a wild population. Fry from wild and domesticated rainbow trout (Oncorhynchus mykiss) crosses, F 1 hybrids, and first- and second-generation backcrosses were released into two natural lakes. Parentage analysis using microsatellite loci facilitated the identification of survivors, so fitness was estimated in nature from the first-feeding stage. Results indicated that under certain conditions, domesticated fish survived at least as well as wild fish within the same environment. Relative growth and survival of the crosses, however, were highly dependent on environment. During the first summer, fastest-growing crosses had the highest survival, but this trend was reversed after one winter and another summer. Although the F 1 hybrids showed evidence of outbreeding depression because of the disruption of local adaptation, there was little evidence of outbreeding depression in the backcrosses, and the second-generation backcrosses exhibited a wild-type phenotype. This information is relevant for assessing the multigenerational risk of escaped or released domesticated fish should they successfully interbreed with wild populations and provides information on how to minimize detrimental impacts of a conservation breeding and/or management programme. These data also further understanding of the selection pressures in nature that maintain submaximal rates of growth. © 2011 Blackwell Publishing Ltd.

Naiman R.J.,University of Washington | Naiman R.J.,University of Western Australia | Alldredge J.R.,Washington State University | Beauchamp D.A.,U.S. Geological Survey | And 14 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2012

Well-functioning food webs are fundamental for sustaining rivers as ecosystems and maintaining associated aquatic and terrestrial communities. The current emphasis on restoring habitat structure - without explicitly considering food webs - has been less successful than hoped in terms of enhancing the status of targeted species and often overlooks important constraints on ecologically effective restoration. We identify three priority food web-related issues that potentially impede successful river restoration: uncertainty about habitat carrying capacity, proliferation of chemicals and contaminants, and emergence of hybrid food webs containing a mixture of native and invasive species. Additionally, there is the need to place these food web considerations in a broad temporal and spatial framework by understanding the consequences of altered nutrient, organic matter (energy), water, and thermal sources and flows, reconnecting critical habitats and their food webs, and restoring for changing environments. As an illustration, we discuss how the Columbia River Basin, site of one of the largest aquatic/riparian restoration programs in the United States, would benefit from implementing a food web perspective. A food web perspective for the Columbia River would complement ongoing approaches and enhance the ability to meet the vision and legal obligations of the US Endangered Species Act, the Northwest Power Act (Fish and Wildlife Program), and federal treaties with Northwest Indian Tribes while meeting fundamental needs for improved river management.

Jones S.R.M.,Canadian Department of Fisheries and Oceans | Forster I.,Center for Aquaculture and Environmental Research | Liao X.,Canadian Department of Fisheries and Oceans | Ikonomou M.G.,Canadian Department of Fisheries and Oceans
Aquaculture | Year: 2012

This experiment investigated a range of dietary nicarbazin concentrations for efficacy against the myxosporean parasite Kudoa thyrsites and for toxicity in seawater-reared Atlantic salmon post-smolts. Nicarbazin was incorporated into diets at 0 (control), 2.5, 5, 10 or 25gkg -1 such that each dose was replicated among three tanks and delivered intermittently over 2155degree-days. Compared with controls, the prevalence and severity of K. thyrsites, determined histologically, were significantly reduced in fish fed diets containing nicarbazin. Nicarbazin residues in skeletal muscle, liver and skin were proportional to dietary concentration between 0 and 10gkg -1 and were associated with a red discolouration of the skin. Cumulative mortality ranged from 0% to 12.4% among groups and was significantly elevated in the 10 and 25gkg -1 groups, relative to control. Weight and condition factor were reduced because of reduced feeding responses to the medicated diets. Feeding responses and appearance of the skin returned to normal and mortality ceased upon resumption of non-medicated diets. In conclusion, dietary nicarbazin was efficacious against K. thyrsites in Atlantic salmon, when included in diets at concentration of at least 2.5gkg -1. Further research will optimise nicarbazin treatment strategies and establish tissue residues following cessation of treatment. © 2012.

Balfry S.,University of British Columbia | Balfry S.,Center for Aquaculture and Environmental Research | Welch D.W.,Kintama Research Services Ltd. | Atkinson J.,University of British Columbia | And 2 more authors.
PLoS ONE | Year: 2011

Early marine migratory behaviour and apparent survival of hatchery-reared Seymour River steelhead (Oncorhynchus mykiss) smolts was examined over a four year period (2006-2009) to assess the impact of various management strategies on improving early marine survival. Acoustically tagged smolts were released to measure their survival using estuary and coastal marine receivers forming components of the Pacific Ocean Shelf Tracking (POST) array. Early marine survival was statistically indistinguishable between releases of summer run and winter run steelhead races, night and day releases, and groups released 10 days apart. In 2009, the survival of summer run steelhead released into the river was again trialed against groups released directly into the ocean at a distance from the river mouth. Apparent survival was improved significantly for the ocean released groups. The health and physiological status of the various release groups were monitored in years 2007-2009, and results indicate that the fish were in good health, with no clinical signs of disease at the time of release. The possibility of a disease event contributing to early marine mortality was further examined in 2009 by vaccinating half of the released fish against common fish diseases (vibriosis, furunculosis). The results suggest that marine survival may be enhanced using this approach, although not to the extent observed when the smolts were transported away from the river mouth before release. In summary, direct experimental testing of different release strategies using the POST array to measure ocean survival accelerated the scientific process by allowing rapid collection of data which enabled the rejection of several existing theories and allowed tentative identification of several new alternative approaches that might improve early marine survival of Seymour River steelhead. © 2011 Balfry et al.

Kim J.-H.,Center for Aquaculture and Environmental Research | Dahms H.-U.,Sangmyung University | Han K.-N.,Inha University
Aquaculture Research | Year: 2013

The river pufferfish Takifugu obscurus is one of the most valuable aquaculture species in South Korea and China. To analyse the effect of rearing densities in the aquaculture of this species, we performed an experiment where T. obscurus was reared for 3 months after hatching at different initial rearing densities (10 fish L-1, 20 fish L-1, and 25 fish L-1) which are similar to rearing densities in aquaculture (10-15 fish L-1). The growth of the high density group (25 fish L-1) was significantly slower than that of the low density group. To determine biomarkers for stress under conditions of high rearing density, we chose six stress-related genes (heat shock proteins (HSPs) 70 and 90β, metallothionein (MT), cytochrome P450 1A (CYP1A), glucocorticoid receptor (GCR) and phosphoenolpyruvate carboxykinase (PEPCK) and evaluated their expression by real-time reverse transcript polymerase chain reaction (real-time RT-PCR). In the high density group, we observed significant up-regulation of genes encoding HSPs 70 and 90β, MT, CYP1A, and PEPCK in liver and brain, but no up-regulation of the GCR. In particular, expression of HSP70, MT and CYP1A was up-regulated in a tissue-specific pattern. Our results demonstrate that growth retardation at high initial rearing densities is associated with stress-induced gene expression. These findings further indicate that molecular biomarkers can be useful to determine the optimal rearing conditions with respect to densities of pufferfish culture. © 2012 John Wiley & Sons Ltd.

Lohmus M.,Center for Aquaculture and Environmental Research | Lohmus M.,National Veterinary Institute | Fredrik Sundstrom L.,Center for Aquaculture and Environmental Research | Bjorklund M.,Uppsala University | Devlin R.H.,Center for Aquaculture and Environmental Research
PLoS ONE | Year: 2010

Background: The neuroendocrine system is an important modulator of phenotype, directing cellular genetic responses to external cues such as temperature. Behavioural and physiological processes in poikilothermic organisms (e.g. most fishes), are particularly influenced by surrounding temperatures. Methodology/Principal Findings: By comparing the development and growth of two genotypes of coho salmon (wild-type and transgenic with greatly enhanced growth hormone production) at six different temperatures, ranging between 8° and 18°C, we observed a genotype-temperature interaction and possible trend in directed neuroendocrine selection. Differences in growth patterns of the two genotypes were compared by using mathematical models, and morphometric analyses of juvenile salmon were performed to detect differences in body shape. The maximum hatching and alevin survival rates of both genotypes occurred at 12°C. At lower temperatures, eggs containing embryos with enhanced GH production hatched after a shorter incubation period than wild-type eggs, but this difference was not apparent at and above 16°C. GH transgenesis led to lower body weights at the time when the yolk sack was completely absorbed compared to the wild genotype. The growth of juvenile GH-enhanced salmon was to a greater extent stimulated by higher temperatures than the growth of the wild-type. Increased GH production significantly influenced the shape of the salmon growth curves. Conclusions: Growth hormone overexpression by transgenesis is able to stimulate the growth of coho salmon over a wide range of temperatures. Temperature was found to affect growth rate, survival, and body morphology between GH transgenic and wild genotype coho salmon, and differential responses to temperature observed between the genotypes suggests they would experience different selective forces should they ever enter natural ecosystems. Thus, GH transgenic fish would be expected to differentially respond and adapt to shifts in environmental conditions compared with wild type, influencing their ability to survive and interact in ecosystems. Understanding these relationships would assist environmental risk assessments evaluating potential ecological effects. © 2010 Lõhmus et al.

PubMed | Center for Aquaculture and Environmental Research
Type: Journal Article | Journal: PloS one | Year: 2017

Growth hormone (GH) transgenic fish have accelerated growth and could improve production efficiency in aquaculture. However, concern exists regarding potential environmental risks of GH transgenic fish should they escape rearing facilities. While environmental effects have been examined in some GH transgenic models, there is a lack of information on whether effects differ among different constructs or strains of transgenic fish. We compared growth and survival of wild-type coho salmon (Oncorhynchus kisutch) fry, a fast-growing GH transgenic strain containing a metallothionein promoter (TMT), and three lines/strains containing a reportedly weaker histone-3 promoter (TH3) in hatchery conditions and semi-natural stream tanks with varying levels of natural food and predators. Rank order of genotype size and survival differed with varying environmental conditions, both within and among experiments. Despite accelerated growth in hatchery conditions, TMT fry gained little or no growth enhancement in stream conditions, had enhanced survival when food was limiting, and inconsistent survival under other conditions. Rank growth was inconsistent in TH3 strains, with one strain having highest, and two strains having the lowest growth in stream conditions, although all TH3 strains had consistently poor survival. These studies demonstrate the importance of determining risk estimates for each unique transgenic model independent of other models.

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