Pink salmon (Oncorhynchus gorbuscha) osmoregulatory development plays a key role in sea louse (Lepeophtheirus salmonis) tolerance

2011 ◽  
Vol 68 (6) ◽  
pp. 1087-1096 ◽  
Author(s):  
M. Sackville ◽  
S. Tang ◽  
L. Nendick ◽  
A.P. Farrell ◽  
C.J. Brauner
Keyword(s):  
System Development ◽  
Pink Salmon ◽  
Infected Fish ◽  
Oncorhynchus Gorbuscha ◽  
Lepeophtheirus Salmonis ◽  
Data Sets ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Immune System Development ◽  
Combining Data ◽  
In The Wild

Sea lice ( Lepeophtheirus salmonis ) of fish-farm origin have been implicated in reducing populations of pink salmon ( Oncorhynchus gorbuscha ) in British Columbia’s Broughton Archipelago. Owing to the physically disruptive nature of louse attachment to fish skin in a hyperosmotic environment, we hypothesize that the impacts on fish performance are ionoregulatory in origin. Therefore, ionoregulatory status was measured in juvenile pink salmon artificially infected in the laboratory and naturally infected in the wild. Body [Na+] of laboratory-infected fish (∼1 week seawater (SW); 0.2–0.4 g) increased significantly by 12% with a single chalimus-4 louse, and by 23% with 2–3 chalimus-3 lice. Mortality over this 24-day trial was 2.4% for fish initially infected with 1–3 lice. Body [Na+] for fish caught with natural infections (∼4–12 weeks SW; 0.5–1.5 g) did not differ from uninfected controls. Combining data sets revealed a “no effect” threshold of 0.5 g for body [Na+] of fish infected with one chalimus-4 louse. We propose that this size-related louse tolerance is associated with hypo-osmoregulatory development, adding to a previously suggested multifactorial mechanism based on epidermal and immune system development. We suggest management bodies consider this fish-mass threshold when planning to minimize risk to wild fish populations.

Diel vertical distribution of early marine phase juvenile pink salmon (Oncorhynchus gorbuscha) and behaviour when exposed to salmon louse (Lepeophtheirus salmonis)

2011 ◽  
Vol 89 (9) ◽  
pp. 796-807 ◽  
Author(s):  
S. Tang ◽  
A.G. Lewis ◽  
M. Sackville ◽  
L. Nendick ◽  
C. DiBacco ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
Pink Salmon ◽  
Distribution Patterns ◽  
Oncorhynchus Gorbuscha ◽  
Lepeophtheirus Salmonis ◽  
Night Time ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Salmon Louse ◽  
Seawater Acclimation

We observed diel vertical migration patterns in juvenile pink salmon ( Oncorhynchus gorbuscha (Walbaum, 1792)) and tested the hypothesis that fish behaviour is altered by exposure to sea lice copepodids. Experiments involved replicated field deployments of a large (9 m) plankton column, which provided a vertical distribution enclosure under natural light and salinity conditions. Diel vertical distributions of juvenile pink salmon were observed during the first 3 weeks of seawater acclimation in both the presence and the absence of the ectoparasitic salmon louse ( Lepeophtheirus salmonis (Krøyer, 1838)). Immediately upon entering seawater, juvenile pink salmon preferred the top 1 m of the water column, but they moved significantly deeper down the vertical water column as seawater acclimation time increased. A significant diel migration pattern was observed, which involved a preference for the surface at night-time, compared with daytime. When fish in the column were exposed to L. salmonis copepodids for 3 h, 43%–62% of fish became infected, fish expanded their vertical distribution range, and significant changes in vertical distribution patterns were observed.

The effect of sea lice (Lepeophtheirus salmonis) on juvenile pink salmon (Oncorhynchus gorbuscha) swimming endurance

2010 ◽  
Vol 67 (12) ◽  
pp. 2045-2051 ◽  
Author(s):  
Paul A. Mages ◽  
Lawrence M. Dill
Keyword(s):  
Pink Salmon ◽  
Sea Lice ◽  
Oncorhynchus Gorbuscha ◽  
Control Fish ◽  
Lepeophtheirus Salmonis ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Swim Performance ◽  
Ecological Implications ◽  
Seaward Migration ◽  
Swimming Endurance

The swimming endurance of naturally and experimentally infected juvenile pink salmon ( Oncorhynchus gorbuscha ) was measured to determine the effects of sea lice ( Lepeophtheirus salmonis ). Salmon naturally infected with adult male and preadult stage lice did not appear to have a reduced swim performance, but when experimentally infected with adult female lice, juvenile salmon showed a reduced ability to swim compared with uninfected control fish, and this effect increased with lice load. A reduced swimming endurance is not only likely to influence predation risk for salmon, but may have other ecological implications, such as slower seaward migration.

scholarly journals Physiological consequences of the salmon louse ( Lepeophtheirus salmonis ) on juvenile pink salmon ( Oncorhynchus gorbuscha ): implications for wild salmon ecology and management, and for salmon aquaculture

2012 ◽  
Vol 367 (1596) ◽  
pp. 1770-1779 ◽  
Author(s):  
C. J. Brauner ◽  
M. Sackville ◽  
Z. Gallagher ◽  
S. Tang ◽  
L. Nendick ◽  
...  
Keyword(s):  
British Columbia ◽  
Ecosystem Health ◽  
Pink Salmon ◽  
Oncorhynchus Gorbuscha ◽  
Lepeophtheirus Salmonis ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Salmon Louse ◽  
Wild Salmon ◽  
Salmon Aquaculture ◽  
The Impact

Pink salmon, Oncorhynchus gorbuscha , are the most abundant wild salmon species and are thought of as an indicator of ecosystem health. The salmon louse, Lepeophtheirus salmonis , is endemic to pink salmon habitat but these ectoparasites have been implicated in reducing local pink salmon populations in the Broughton Archipelago, British Columbia. This allegation arose largely because juvenile pink salmon migrate past commercial open net salmon farms, which are known to incubate the salmon louse. Juvenile pink salmon are thought to be especially sensitive to this ectoparasite because they enter the sea at such a small size (approx. 0.2 g). Here, we describe how ‘no effect’ thresholds for salmon louse sublethal impacts on juvenile pink salmon were determined using physiological principles. These data were accepted by environmental managers and are being used to minimize the impact of salmon aquaculture on wild pink salmon populations.

The effect of sea lice infestation on the salinity preference and energetic expenditure of juvenile pink salmon (Oncorhynchus gorbuscha)

2007 ◽  
Vol 64 (4) ◽  
pp. 672-680 ◽  
Author(s):  
Sandra J Webster ◽  
Lawrence M Dill ◽  
Kevin Butterworth
Keyword(s):  
Pink Salmon ◽  
Fold Increase ◽  
Infected Fish ◽  
Oncorhynchus Gorbuscha ◽  
Control Fish ◽  
Energetic Cost ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Freshwater Habitats ◽  
Salinity Preference ◽  
The Cost

Ocean-going juvenile salmonids heavily infected with salmon louse, Lepeophtheirus salmonis, have been observed prematurely returning to freshwater. This change in salinity preference may be an attempt either to regain osmotic balance or to remove the lice. For either hypothesis to be true, freshwater habitats must provide infected fish with a higher net fitness than saltwater habitats. The objectives of this study were to use behavioural titration to quantify the energetic cost of different salinities to infected and uninfected pink salmon (Oncorhynchus gorbuscha) and to determine if infection alters salinity preference. Results demonstrate that infection changes the salinity preference of fish from saltwater to freshwater. The cost paid by these freshwater-preferring infected fish foraging in saltwater increased with lice density during trials conducted between 13–33 days after infection. Other infection-induced behavioural changes include a 14-fold increase in the jumping frequency of infected versus control fish and a decrease in foraging between 13 and 33 days after infection.

Sea lice (Lepeophtheirus salmonis) infestations and the productivity of pink salmon (Oncorhynchus gorbuscha) in the Broughton Archipelago, British Columbia, Canada

2011 ◽  
Vol 68 (1) ◽  
pp. 17-29 ◽  
Author(s):  
Martin Krkošek ◽  
Ray Hilborn
Keyword(s):  
British Columbia ◽  
Large Scale ◽  
Spatial Scales ◽  
Population Decline ◽  
Pink Salmon ◽  
Sea Lice ◽  
Oncorhynchus Gorbuscha ◽  
Lepeophtheirus Salmonis ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Lice Infestations

The spread of salmon lice ( Lepeophtheirus salmonis ) from salmon farms may threaten some wild salmon populations. Infestations of wild juvenile pink salmon ( Oncorhynchus gorbuscha ) have been associated with high mortality and population decline. Using stock–recruit data for pink salmon from the central coast of British Columbia, we analyzed how fishing mortality and spatial covariation combine with louse infestation to affect pink salmon population dynamics. The results indicate substantial coherence in survival at nested spatial scales — large-scale regional covariation and smaller scale covariation within management areas. Populations exposed to salmon farms (those from the Broughton Archipelago) show a sharp decline in productivity during sea lice infestations relative to pre-infestation years. Unexposed populations (comprising four management areas) did not experience a change in productivity during infestation years and had similar productivity to exposed populations before infestations. Our results suggest that sea lice infestations may result in declines of pink salmon populations and that management and policy of salmon farms should consider protecting wild juvenile salmon from exposure to sea lice.

Differentiating size-dependent responses of juvenile pink salmon (Oncorhynchus gorbuscha) to sea lice (Lepeophtheirus salmonis) infections

2011 ◽  
Vol 6 (2) ◽  
pp. 213-223 ◽  
Author(s):  
Ben J.G. Sutherland ◽  
Stuart G. Jantzen ◽  
Dan S. Sanderson ◽  
Ben F. Koop ◽  
Simon R.M. Jones
Keyword(s):  
Pink Salmon ◽  
Sea Lice ◽  
Oncorhynchus Gorbuscha ◽  
Lepeophtheirus Salmonis ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Size Dependent

scholarly journals First Report of a Sea Louse, Lepeophtheirus salmonis, Infestation on Juvenile Pink Salmon, Oncorhynchus gorbuscha, in Nearshore Habitat

2003 ◽  
Vol 117 (4) ◽  
pp. 634 ◽  
Author(s):  
Alexandra B. Morton ◽  
Rob Williams
Keyword(s):  
Salmo Trutta ◽  
Pink Salmon ◽  
Sea Lice ◽  
Oncorhynchus Gorbuscha ◽  
Lepeophtheirus Salmonis ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Sea Trout ◽  
Close Proximity ◽  
Lethal Limit ◽  
Nearshore Habitat

High infestation rates of the Sea Louse (Lepeophtheirus salmonis) have been reported on juvenile salmonids in Europe since 1989; however, this species has not been reported on juvenile Pacific salmonids until now. Magnitude of Sea Lice infestation was examined in 2001 on juvenile Pink Salmon (Oncorhynchus gorbuscha) migrating through a British Columbia archipelago. On average, the 751 juvenile Pink Salmon sampled weighed 2.25 g (± 0.039 SE), were infected with 11.3 (± 0.41 SE) Sea Lice per fish and 6.1 (± 0.24SE) Sea Lice per gram host weight. Fully 75.0% of fish were infected at loads equivalent to or higher than the lethal limit reported for much larger Sea Trout (Salmo trutta) post-smolts. Abundance (Kruskal-Wallis statistic = 100.95, p<0.0001) and intensity (KW= 70.05, p<0.0001) of lice, and mean number of lice/g host weight (K-W= 112.23, p<0.0001) were significantly higher in juvenile Pink Salmon in close proximity to salmon farms, than in Pink Salmon distant from salmon farms.

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