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 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.

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 Tambaqui growth and survival when exposed to different photoperiods

2006 ◽  
Vol 36 (3) ◽  
pp. 381-384 ◽  
Author(s):  
Paulo Henrique Rocha Aride ◽  
Rodrigo Roubach ◽  
Sérgio Ricardo Nozawa ◽  
Adalberto Luís Val
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Specific Growth ◽  
Continuous Light ◽  
Control Fish ◽  
Continuous Darkness ◽  
Growth And Survival ◽  
Colossoma Macropomum ◽  
Fish Weight ◽  
Natural Photoperiod

The use of different photoperiods (light) were investigated during tambaqui (Colossoma macropomum) juvenile growth under captivity. Light intensity tested was: continuous dark (24hrs without light), natural photoperiod simulation (10hrs of light and 14hrs without light) and continuous light (24 with light). No mortality was recorded among treatments. Significant differences was observed after 50 days of experiment among mean fish weight, fish kept under a continuous darkness showed a better specific growth rate (6.02%) when compared to control fish (natural photo period, 3.67%). Fish exposed to continuous light presented the lowest mean specific growth rate (2.04%). It is possible to improve tambaqui juvenile weight gain performance when kept under continuous darkness.

First confirmation of salmonid alphavirus infection in Arctic char Salvelinus alpinus and in Austria

2018 ◽  
Vol 130 (1) ◽  
pp. 71-76
Author(s):  
E Lewisch ◽  
T Frank ◽  
H Soliman ◽  
O Schachner ◽  
A Friedl ◽  
...  
Keyword(s):  
Salvelinus Alpinus ◽  
Arctic Char ◽  
Alphavirus Infection

scholarly journals Investigating the morphological and genetic divergence of arctic char ( Salvelinus alpinus) populations in lakes of arctic Alaska

2021 ◽  
Author(s):  
Stephen L. Klobucar ◽  
Jessica A. Rick ◽  
Elizabeth G. Mandeville ◽  
Catherine E. Wagner ◽  
Phaedra Budy
Keyword(s):  
Genetic Divergence ◽  
Salvelinus Alpinus ◽  
Arctic Char ◽  
Arctic Alaska

Influence of Parr Growth, Lake Morphology, and Freshwater Parasites on the Degree of Anadromy in Different Populations of Arctic Char (Salvelinus alpinus) in Northern Norway

1994 ◽  
Vol 51 (6) ◽  
pp. 1229-1246 ◽  
Author(s):  
Knut Kristoffersen ◽  
Morten Halvorsen ◽  
Lisbeth Jørgensen
Keyword(s):  
Salvelinus Alpinus ◽  
Relative Size ◽  
Significant Negative Correlation ◽  
Relative Volume ◽  
Arctic Char ◽  
Northern Norway ◽  
Length Relationship ◽  
Lake Morphology ◽  
Different Populations ◽  
Profundal Zone

Anadromy of nine lake populations of Arctic char (Salvelinus alpinus) in northern Norway was scored on the following criteria: prevalence of marine parasites, fish size, and size at maturity. In general, anadromy dominated in shallow lakes and residency dominated in deep lakes. The anadromy scores of the populations were significantly higher in lakes without a profundal zone compared with lakes with a profundal zone. There was also a significant negative correlation between the relative volume of the profundal zone (RPV) and the degree of anadromy and between RPV and mean parr length at ages 2+ and 3+. However, differences in parr growth could not explain all the observed variation in anadromy, and the correlation between mean parr length at ages 2+ and 3+ and the degree of anadromy in the different populations was not significant. In addition to the effect on parr growth, lake morphology seemed to influence the degree of anadromy through the relative size of different habitats, which in turn affects the number of available niches. The parr weight/length relationship and infection with the freshwater parasites Phyllodistomum umblae and Diphyllobothrium spp. did not affect the degree of anadromy.

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.

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