scholarly journals Effects of laboratory salmon louse infection on osmoregulation, growth and survival in Atlantic salmon

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Per Gunnar Fjelldal ◽  
Tom J Hansen ◽  
Ørjan Karlsen
Keyword(s):  
Atlantic Salmon ◽  
Infection Intensity ◽  
Infected Fish ◽  
Control Fish ◽  
Control Group ◽  
Threshold Values ◽  
Growth And Survival ◽  
Salmon Lice ◽  
Intensity Threshold ◽  
Specific Growth Rates

Abstract Anadromous Atlantic salmon (Salmo salar) rely on long ocean migrations to build energy stores for maturation and spawning. In seawater, wild Atlantic salmon are threatened by high salmon lice (Lepeophtheirus salmonis) infestation levels resulting from intensive salmonid sea-cage aquaculture. Salmon lice infection can cause a stress response and an osmotic imbalance in the host. The lice infection intensity threshold values for these responses, however, remain to be identified in Atlantic salmon. In order to define this under laboratory conditions, individually tagged F1 wild origin Atlantic post-smolts (40 g) were infected with salmon lice copepodids or left as uninfected controls. Twenty-eight days post infection, infected post-smolts had a mean of 0.38 (range of 0.07–0.9) mobile lice g−1 fish weight. During this period, specific growth rates (SGRs) were lower in infected than control fish (0.4 vs 1.0% day−1). Higher plasma Na+, Cl− and osmolality in infected fish also indicate osmoregulatory impairment. SGR correlated negatively with plasma Na+, Cl−, osmolality and cortisol in the infected, but not in the control group. Infection intensity (lice g−1 fish) correlated positively with mortality rate and plasma Na+, Cl−, osmolality and cortisol and correlated negatively with SGR and condition factor. Calculated lice intensity threshold values for changes in plasma ions were 0.18 lice g−1 for plasma Cl−, and 0.22 lice g−1 for plasma Na+. Moribund infected fish occurred at infection intensities above 0.2 lice g−1, and these fish had extreme plasma Cl−, Na+, osmolality and cortisol levels. There was a positive correlation between plasma cortisol and plasma Na+, Cl− and osmolality in infected fish. This study provides vital information that can be used to define thresholds in the monitoring and conservation of wild Atlantic salmon populations affected by aquaculture-driven salmon lice infestations.

scholarly journals Effects of laboratory salmon louse infection on Arctic char osmoregulation, growth and survival

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
P G Fjelldal ◽  
T J Hansen ◽  
Ø Karlsen ◽  
D W Wright
Keyword(s):  
Salvelinus Alpinus ◽  
Infection Intensity ◽  
Infected Fish ◽  
Arctic Char ◽  
Control Fish ◽  
Growth And Survival ◽  
Salmon Lice ◽  
Fish Weight ◽  
Survival And Reproduction ◽  
Anadromous Migration

Abstract High salmon lice (Lepeophtheirus salmonis) infestation levels resulting from intensive salmonid sea-cage aquaculture can threaten populations of wild salmonid hosts. This includes anadromous Arctic char (Salvelinus alpinus), which rely on short migrations into more productive seawater environments to build energy stores for maturation, spawning and over-wintering in freshwater. Elevated salmon lice burdens may limit the benefits of migration by constraining osmoregulation, growth, survival and reproduction. To test for these effects, we simulated anadromous migration in tanks by transferring individually tagged Arctic char smolts (n = 352, averaging 133 g) to seawater where they were infected with salmon lice or left as uninfected controls for 1 month, and then transferring them back to freshwater for 2 months. After the seawater phase, infected post-smolts had a mean of 0.33 (range of 0.09–0.91) mobile lice g−1 fish weight. At this point, specific growth rates (SGRs) dropped in infected compared to control fish (0.1% vs. 1.6% day−1). Higher plasma Na+ and osmolality in infected fish also indicate osmoregulatory impairment. Throughout the study, mortality was 18.2% and 1.7% in infected and control groups, but sexual maturation was low and comparable between groups. Infection intensity correlated positively with mortality rate and plasma Cl−, and correlated negatively with SGR and condition factor (CF). CF dropped (ΔCF < 0) at intensities of >0.09 lice g−1 fish weight, and intensities of >0.3 causing zero or negative SGRs and increased mortality were particularly concerning. If infection intensities reach these levels in the wild, char could be impacted by growth restrictions and increased mortality rates, which potentially cause shorter migration durations, lowered reproductive success and possibly also selection against anadromy. This study provides vital information for conservation practitioners wanting to understand the physiologically derived burden salmon lice can have on Arctic char populations, and can be used to define thresholds in the monitoring and conservation of Arctic char populations affected by aquaculture-driven salmon lice infestations.

scholarly journals Chimeric Protein IPath® with Chelating Activity Improves Atlantic Salmon’s Immunity against Infectious Diseases

Vaccines ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 361
Author(s):  
Valentina Valenzuela-Muñoz ◽  
Bárbara P. Benavente ◽  
Antonio Casuso ◽  
Yeny Leal ◽  
Cristian Gallardo-Escárate
Keyword(s):  
Immune Response ◽  
Atlantic Salmon ◽  
Iron Metabolism ◽  
Iron Transport ◽  
Aeromonas Salmonicida ◽  
Transcriptional Analysis ◽  
Control Fish ◽  
Control Group ◽  
Commercial Fish ◽  
Chelating Activity

Infection processes displayed by pathogens require the acquisition of essential inorganic nutrients and trace elements from the host to survive and proliferate. Without a doubt, iron is a crucial trace metal for all living organisms and also a pivotal component in the host–parasite interactions. In particular, the host reduces the iron available to face the infectious disease, increasing iron transport proteins’ expression and activating the heme synthesis and degradation pathways. Moreover, recent findings have suggested that iron metabolism modulation in fish promotes the immune response by reducing cellular iron toxicity. We hypothesized that recombinant proteins related to iron metabolism could modulate the fish’s immune system through iron metabolism and iron-responsive genes. Here a chimeric iron transport protein (IPath®) was bioinformatically designed and then expressed in a recombinant bacterial system. The IPath® protein showed a significant chelating activity under in vitro conditions and biological activity. Taking this evidence, a vaccine candidate based on IPath® was evaluated in Atlantic salmon challenged with three different fish pathogens. Experimental trials were conducted using two fish groups: one immunized with IPath® and another injected with adjutant as the control group. After 400 accumulated thermal units (ATUs), two different infection trials were performed. In the first one, fish were infected with the bacterium Aeromonas salmonicida, and in a second trial, fish were exposed to the ectoparasite Caligus rogercresseyi and subsequently infected with the intracellular bacterium Piscirickettsia salmonis. Fish immunized with IPath® showed a significant delay in the mortality curve in response to A. salmonicida and P. salmonis infections. However, no significant differences between infected and control fish groups were observed at the end of the experiment. Notably, sea lice burden reduction was observed in vaccinated Atlantic salmon. Transcriptional analysis evidenced a high modulation of iron-homeostasis-related genes in fish vaccinated with IPath® compared to the control group during the infection. Moreover, increasing expression of Atlantic salmon IgT was associated with IPath® immunization. This study provides evidence that the IPath® protein could be used as an antigen or booster in commercial fish vaccines, improving the immune response against relevant pathogens for salmon aquaculture.

The effect of porcine somatotropin on growth, and survival in seawater of Atlantic salmon (Salmo salar) parr

1976 ◽  
Vol 54 (4) ◽  
pp. 531-535 ◽  
Author(s):  
M. P. Komourdjian ◽  
R. L. Saunders ◽  
J. C. Fenwick
Keyword(s):  
Growth Hormone ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Growth Hormone Treatment ◽  
Hormone Treatment ◽  
Control Fish ◽  
Growth And Survival ◽  
Atlantic Salmon Salmo Salar ◽  
Porcine Somatotropin

The effects of porcine growth hormone on growth and salinity tolerance were studied in Atlantic salmon (Salmo salar) parr. Fish were held in freshwater at 11.5 °C during June and July under a photoperiod with light to dark periods opposite to the prevailing natural conditions. Fish treated with 1.0 μg/g body weight of growth hormone preparation on alternate days were significantly longer (P <.05), after 4 weeks, than placebo-injected controls. All hormone-injected fish survived transfer to seawater, 30‰ salinity. But under the same conditions, placebo-injected control fish showed a high mortality rate. Growth-hormone treatment caused a darkening of fin margins and a yellowing of the operculae and fin surfaces. The silvering which normally accompanies smoltification was not observed. The role of growth hormone in eliciting these actions and its possible role in the parr–smolt transformation are discussed.

The development of salmon lice (Lepeophtheirus salmonis) on artificially infected post smolts of sea trout (Salmo trutta)

1998 ◽  
Vol 76 (5) ◽  
pp. 970-977 ◽  
Author(s):  
Pål Arne Bjørn ◽  
Bengt Finstad
Keyword(s):  
Salmo Trutta ◽  
Adult Stage ◽  
Infection Intensity ◽  
Developmental Rate ◽  
Infected Fish ◽  
Random Pattern ◽  
Lepeophtheirus Salmonis ◽  
Skin Damage ◽  
Sea Trout ◽  
Salmon Lice

The developmental rate, distribution on the host, and pathogenicity (skin damage) of salmon lice (Lepeophtheirus salmonis) were tested on artificially infected sea trout (Salmo trutta) post smolts. Male lice developed faster than females, taking approximately 29 and 38 days, respectively, to reach the adult stage at 10°C. During this time, infection intensity decreased. Less than 40% of the lice reached the adult stage, and their distribution changed from overdispersed towards a more random pattern. The chalimus larvae of the lice exhibited a preference for the gills and fins, especially the dorsal fin, and caused only minor skin damage. When the preadult and adult stages appeared, skin damage became severe, especially on the preferred head and dorsal areas, causing mortality of the most heavily infected fish.

scholarly journals Survival and growth of sea-ranched Atlantic salmon, Salmo salar L., treated against sea lice before release

2006 ◽  
Vol 63 (7) ◽  
pp. 1317-1325 ◽  
Author(s):  
Ove T. Skilbrei ◽  
Vidar Wennevik
Keyword(s):  
Atlantic Salmon ◽  
Treated Group ◽  
Sea Lice ◽  
Control Fish ◽  
Release Date ◽  
The Third ◽  
Salmon Lice ◽  
Survival And Growth ◽  
The Difference ◽  
Adipose Fin

Abstract Cultured Atlantic salmon smolts were treated with Slice®, orally administered emamectin benzoate, before release in the Dale River, western Norway, to study the potential effects of sea lice during the early stages of their marine phase. In all, 10 470 treated and untreated (control) fish from ten family groups were adipose fin-clipped, coded-wire tagged, and released on three different dates in 2002 (11 May, 25 May, and 7 June), which coincided with the natural smolt run. The percentage of released smolts recaptured as one-sea-winter salmon in 2003 did not differ between the treated and untreated groups released on the two dates in May 2002, but the recapture rate of fish from the treated group released on 7 June 2002 was almost twice that of the controls. The weights of the recaptured one-sea-winter salmon tended to decline from the first to the third release date, and one-sea-winter salmon from the treated groups were approximately 15% heavier than the controls. The difference in recapture rate between the treated and untreated groups increased after inclusion of the two-sea-winter and three-sea-winter salmon recaptured in 2004 and 2005, respectively. We conclude that the infestation level of salmon lice changed from non-lethal to lethal levels during the period of the smolt migration in 2002 and that non-lethal infestation levels may adversely affect Atlantic salmon populations by reducing the growth rate of fish and, consequently, their size at spawning.

Biologging in combination with biotelemetry reveals behavior of Atlantic salmon following exposure to capture and handling stressors

2019 ◽  
Vol 76 (12) ◽  
pp. 2176-2183
Author(s):  
Robert J. Lennox ◽  
Jacqueline M. Chapman ◽  
William M. Twardek ◽  
Franziska Broell ◽  
Kristin Bøe ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Atlantic Salmon ◽  
Null Model ◽  
Control Fish ◽  
Control Group ◽  
Sample Population ◽  
Accelerometer Data ◽  
Air Exposure ◽  
Data Loggers ◽  
Total Body

We investigated the response of Atlantic salmon (Salmo salar) to capture and handling stressors by analyzing fine-scale locomotor activity using accelerometer data loggers and broader-scale movements by tracking migration with radiotelemetry. Half the sample population was exposed to experimental exercise and air exposure and released with a control group to simulate fisheries handling. All but two of the surviving fish (both in the treatment group) returned to the counting fence to resume the 2016 spawning migration (survival = 86%–91%). There were no differences in postrelease locomotor activity, measured by an index of total body action (jerk), between control and treatment salmon (p = 0.81). Comparison of mean time to return to the counting fence against a null model revealed that treatment salmon were significantly delayed in returning to the counting fence (p < 0.01), whereas control fish were not (p = 0.24). Both the abiotic environment and human interactions influenced locomotor activity of the migratory fish and synchrony of the migration with untreated conspecifics.

Distribution of Atlantic salmon (Salmo salar) postsmolts of different origins in the Bay of Fundy and Gulf of Maine and evaluation of factors affecting migration, growth, and survival

2005 ◽  
Vol 62 (6) ◽  
pp. 1363-1376 ◽  
Author(s):  
Gilles L Lacroix ◽  
Derek Knox
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Gulf Of Maine ◽  
Fish Larvae ◽  
Surface Current ◽  
Clupea Harengus ◽  
Bay Of Fundy ◽  
Growth And Survival ◽  
Atlantic Salmon Salmo Salar ◽  
Salmon Lice

Atlantic salmon (Salmo salar) postsmolts surveyed by surface trawling in the Bay of Fundy and Gulf of Maine during 2001–2003 were aggregated in several areas in the Bay of Fundy and dispersed over a broader area in the Gulf of Maine. Postsmolt distribution reflected the major surface-current vectors and was independent of origin (wild vs. hatchery, inner vs. outer Bay of Fundy). Migration proceeded without disruption, and marked wild postsmolts from both the inner and outer Bay of Fundy were recaptured in the outer Bay of Fundy and the Gulf of Maine, where their distribution overlapped the commercial fishery for Atlantic herring (Clupea harengus). Marked postsmolts of wild origin were recaptured more frequently than those of hatchery origin but the overall density was low, and no schools of postsmolts were encountered that could offer protection from predators. Temperature and salinity in postsmolt habitat were favourable for growth and survival. Postsmolts were in excellent condition and had no bacterial or viral pathogens or salmon lice (Lepeophtheirus salmonis). They were feeding on pelagic prey (amphipods, euphausiids, and fish larvae) and the period of accelerated marine growth had started, indicating that environmental conditions and food supply were not limiting growth and survival.

scholarly journals Impacts of salmon lice on mortality, marine migration distance and premature return in sea trout

2020 ◽  
Vol 635 ◽  
pp. 151-168 ◽  
Author(s):  
RM Serra-Llinares ◽  
T Bøhn ◽  
Ø Karlsen ◽  
R Nilsen ◽  
C Freitas ◽  
...  
Keyword(s):  
Fresh Water ◽  
Salmo Trutta ◽  
Statistical Power ◽  
Fork Length ◽  
Control Fish ◽  
Control Group ◽  
Salmon Lice ◽  
Artificial Infestation ◽  
Marine Migration ◽  
Feeding Resources

Brown trout Salmo trutta (L.) is a facultative anadromous species, where a portion of individuals in populations with access to the sea perform migrations to use the richer feeding resources. We investigated the effect of salmon lice Lepeophtheirus salmonis (Krøyer 1837) infestation on the survival and behaviour of wild trout post-smolts (average fork length = 180 mm) during their marine migration. Comparisons of the marine migratory behaviour were made between an artificially infested group (n = 74) and a control group (n = 71) in an area with low natural lice infestation pressure. Artificial infestation was estimated to cause 100% prevalence and a mean intensity of 65 lice fish-1 (mean relative intensity of 2.4 lice g-1 fish). Survival analysis showed limited statistical power but revealed lice-induced mortality, with an estimated hazard ratio of 2.73 (95% CI = 1.04-7.13) compared to the control group, when data from a previous pilot study were included. Surviving individuals in the infested group additionally responded by residing closer to fresh water while at sea, and by prematurely returning to fresh water. On average, infested fish returned to fresh water after only 18 d at sea, while control fish spent on average 100 d at sea. The residency in the inner part of the fjord and the premature return to fresh water represent an adaptive behavioural response to survive the infestation, at the probable cost of reduced growth opportunities and compromised future fitness.

scholarly journals A Sequential Study of the Light and Electron Microscopic Liver Lesions of Infectious Anemia in Atlantic Salmon (Salmo salar L.)

1995 ◽  
Vol 32 (5) ◽  
pp. 466-478 ◽  
Author(s):  
L. Speilberg ◽  
Ø. Evensen ◽  
B. H. Dannevig
Keyword(s):  
Atlantic Salmon ◽  
Cell Types ◽  
Infected Fish ◽  
Control Fish ◽  
Peliosis Hepatis ◽  
Liver Lesions ◽  
Endothelial Lining ◽  
Electron Microscopic ◽  
Infectious Salmon Anemia ◽  
Sinusoidal Endothelium

The present study describes light and electron microscopic changes in the liver of Atlantic salmon during the development of infectious salmon anemia (ISA). Atlantic salmon postsmolts weighing 80-100 g were infected by intraperitoneal injections, and liver samples were collected sequentially between day 0 and day 25 post infection (p.i.), with time intervals of 3-4 days. At each collection time, livers from five infected fish and two control fish were examined. Changes involving the perisinusoidal macrophages were observed by transmission electron microscopy, from day 4 p.i. Large vacuoles, containing a fine-granular material with low electron density, accumulated in the cytoplasm. These changes persisted and became more severe throughout the investigation, leading to a considerable increase in the size of the cells. At day 14 p.i., degenerative features of the sinusoidal endothelium were observed. By day 18 p.i., areas of the liver were devoid of a sinusoidal endothelial lining, bringing hepatocytes in direct contact with blood cells. At this stage, the sinusoids were moderately congested. From day 21 p.i., heavy sinusoidal congestion, peliosis hepatis, and degeneration of the hepatocytes were observed. No virus was observed in any of the inhabitant cell types of the liver. Gross and light microscopic changes were first recorded at day 18 p.i., as was a significant decrease in the hematocrit values. By day 25 p.i., characteristic multifocal, confluent, hemorrhagic necroses were present. Results of the present investigation suggest that the liver lesions observed with ISA are not the result of the development of an anemia alone or caused by direct viral damage to hepatocytes. Hepatocellular degeneration succeeded changes in the perisinusoidal macrophages and degeneration of the sinusoidal endothelium. These changes may have impeded the sinusoidal blood flow and hence caused an ischemic hepatocellular necrosis.

scholarly journals Effect of visible implant elastomers (VIE) and coded wire tags (CWT) on the growth, survival, and tag retention of juvenile European whitefish (Coregonus lavaretus)

2019 ◽  
Vol 27 (2) ◽  
pp. 64-71
Author(s):  
Michał Kozłowski ◽  
Mirosław Szczepkowski ◽  
Iwona Piotrowska ◽  
Bożena Szczepkowska
Keyword(s):  
Body Weight ◽  
Control Fish ◽  
Coregonus Lavaretus ◽  
Feed Conversion ◽  
Growth And Survival ◽  
Tag Retention ◽  
Weight Variation ◽  
Specific Growth Rates ◽  
Two Stages ◽  
Coded Wire Tags

Abstract This study examined the effect of visual implant elastomers (VIE) and coded wire tags (CWT) on the growth, survival, and tag retention of juvenile European whitefish, Coregonus lavaretus (L.), (mean body weight 18.7 ± 0.4 g, mean body length 9.7 ± 0.4 cm). The VIE tags were implanted subcutaneously in the anterior head, and the CWTs were implanted intramuscularly under the left gill operculum. The experiment consisted of two stages. The first stage (70 days) examined the effects of tagging on growth and survival, while the second stage (days 71-140) focused on assessing tag retention. Daily and specific growth rates, feed conversion factor, condition factor, coefficient of body weight variation, and survival did not differ significantly between the control fish and those tagged with the VIE tags and CWTs. Tag retention was high in the fish tagged with both VIE tags (100%) and CWTs (93%).

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