There is a growing interest in Atlantic salmon (Salmo salar) aquaculture to extend the time fish are reared in freshwater (FW) recirculating aquaculture systems (RAS), producing larger FW salmon that can then be induced to undergo smoltification before transfer into marine net pens for grow-out and harvest. Smolts can be produced by photoperiod (PT) manipulation in RASs, but little is known about how delaying smoltification to larger body sizes affects susceptibility to elevated CO levels (hypercapnia), which can occur at high stocking densities in FW RAS or during transport from FW RAS rearing facilities to marine net pens. To address this, Atlantic salmon were reared from hatch to one of three different sizes (~230, ~580, or ~1300 g) in FW (3 ppt) under continuous light (24:0, light:dark). Once fish reached the desired sizes, a group of salmon were maintained on continuous light 24L:0D to serve as a control salmon. A second group of salmon were exposed to 8 weeks of 12L:12D and then to 4 weeks of 24L:0D to serve as PT treatment salmon, which is the PT manipulation commonly used in Atlantic salmon aquaculture to induce smoltification. At the end of PT manipulation, both control and PT treatment salmon were exposed to 0% or 1.5% CO (30 mg/L) for 96 h in FW and then transferred to air-equilibrated seawater (SW, 35 ppt, normocapnia). Salmon were sampled at the end of the 96-h FW CO exposure and at 24 h and 7 days in SW for measurements of blood ion/acid-base status, muscle water content (MWC), and gill and kidney Na/K ATPase (NKA) activity. Exposure to 96 h of CO in FW resulted in acid-base disturbances in fish from all three size classes, with decreases in blood pH and increases in blood PCO and plasma [HCO ] but no mortality. Despite these large acid-base disturbances in FW, after transfer to normocapnic SW, there were no significant effects of CO exposure on extracellular blood pH, intracellular red blood cell pH, or plasma osmoregulatory status for all three sizes of post-smolt salmon. In general, SW transfer was associated with significant increases in plasma ions and osmolality, as well as gill and kidney NKA activity after 24 h and 1 week in SW with no significant impacts between different sizes of salmon. Thus, exposure to 30 mg CO/L that mimics levels experienced during transport from FW RAS to an SW transfer site may have minimal effects on Atlantic salmon smolts up to 1300 g.
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http://dx.doi.org/10.1111/jfb.15957 | DOI Listing |
Comp Biochem Physiol A Mol Integr Physiol
January 2025
Department of Zoology, University of British Columbia, Vancouver, Canada.
In a previous study, we demonstrated successful regeneration of Atlantic salmon gill tissue following up to 50 % filament resection. The present study explored 1) the capacity of gill tissue to regenerate following more severe trauma, 2) if regeneration potential varies across regions of the arch, and 3) how tissue loss impacts the physiology of neighboring unresected filaments. Fish were divided between two resected groups and a control non-resected one.
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January 2025
Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, Umeå SE-907 36, Sweden.
Pharmaceutical contaminants have spread in natural environments across the globe, endangering biodiversity, ecosystem functioning, and public health. Research on the environmental impacts of pharmaceuticals is growing rapidly, although a majority of studies are still conducted under controlled laboratory conditions. As such, there is an urgent need to understand the impacts of pharmaceutical exposures on wildlife in complex, real-world scenarios.
View Article and Find Full Text PDFAnal Bioanal Chem
January 2025
Statistical Engineering Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, 20899-8980, USA.
Closely related species of Salmonidae, including Pacific and Atlantic salmon, can be distinguished from one another based on nucleotide sequences from the cytochrome c oxidase sub-unit 1 mitochondrial gene (COI), using ensembles of fragments aligned to genetic barcodes that serve as digital proxies for the relevant species. This is accomplished by exploiting both the nucleotide sequences and their quality scores recorded in a FASTQ file obtained via Next Generation (NextGen) Sequencing of mitochondrial DNA extracted from Coho salmon caught with hook and line in the Gulf of Alaska. The alignment is done using MUSCLE (Muscle 5.
View Article and Find Full Text PDFFEMS Microbiol Ecol
January 2025
Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Trondheim, Norway.
In this study, we investigated the influence of host genetics and environmental microbiomes on the early gut microbiome of Atlantic salmon. We aimed at rearing the fish in either r- or K-selected environments, where the r-selected environment would be expected to be dominated by fast-growing opportunistic bacteria and thus represent more detrimental microbial environment than the K-selected water. Eggs from both wild and aquaculture strains of Atlantic salmon were hatched under germ-free conditions.
View Article and Find Full Text PDFCan J Microbiol
January 2025
Agriculture and Agri-Food Canada, Lacombe Research and Development Centre, Lacombe, AB T4L 1W1, Canada.
The use of probiotics is an alternative approach to mitigate the proliferation of antimicrobial resistance in aquaculture. In our study, we examined the effects of GG (ATCC 53103, LGG) delivered in-feed on the weight, length, skin mucus, and faecal microbiomes of Atlantic salmon. We also challenged the salmon with 2004-05MF26 (Asal2004) and assessed the mortality.
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