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.

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.

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.

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.

Sea lice infection of juvenile pink salmon (Oncorhynchus gorbuscha): effects on swimming performance and postexercise ion balance

2011 ◽  
Vol 68 (2) ◽  
pp. 241-249 ◽  
Author(s):  
L. Nendick ◽  
M. Sackville ◽  
S. Tang ◽  
C. J. Brauner ◽  
A. P. Farrell
Keyword(s):  
Swimming Performance ◽  
Life Stage ◽  
Pink Salmon ◽  
Infection Intensity ◽  
Sea Lice ◽  
Whole Body ◽  
Oncorhynchus Gorbuscha ◽  
Swimming Velocity ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Average Body Mass

Sea lice ( Lepeophtheirus salmonis ) infection negatively affected swimming performance and postswim body ion concentrations of juvenile pink salmon ( Oncorhynchus gorbuscha ) at a 0.34 g average body mass but not at 1.1 g. Maximum swimming velocity (Umax) was measured on over 350 individual pink salmon (0.2–3.0 g), two-thirds of which had a sea lice infection varying in intensity (one to three sea lice per fish) and life stage (chalimus 1 to preadult). For fish averaging 0.34 g (caught in a nearby river free of sea lice and transferred to seawater before being experimentally infected), the significant reduction in Umax was dependent on sea lice life stage, not intensity, and Umax decreased only after the chalimus 2 life stage. Experimental infections also significantly elevated postswim whole body concentrations of sodium (by 23%–28%) and chloride (by 22%–32%), but independent of sea lice developmental stage or infection intensity. For fish averaging 1.1 g (captured in seawater with existing sea lice), the presence of sea lice had no significant effect on either Umax or postswim whole body ions. Thus, a single L. salmonis impacted swimming performance and postswim whole body ions of only the smallest pink salmon and with a sea louse stage of chalimus 3 or greater.

scholarly journals Prevalence, abundance, and distribution of Lepeoptheirus salmonis (Krøyer, 1837) and Caligus elongatus (Nordmann, 1832) on wild sea trout Salmo trutta L.

2008 ◽  
Vol 65 (2) ◽  
pp. 171-173 ◽  
Author(s):  
K. Urquhart ◽  
C. C. Pert ◽  
R. Kilburn ◽  
R. J. Fryer ◽  
I. R. Bricknell
Keyword(s):  
Salmo Trutta ◽  
East Coast ◽  
Sea Lice ◽  
Lepeophtheirus Salmonis ◽  
Marine Science ◽  
Sea Trout ◽  
Anterior Dorsal ◽  
Abundance And Distribution

Abstract Urquhart, K., Pert, C. C., Kilburn, R., Fryer, R. J., and Bricknell, I. R. 2008. Prevalence, abundance, and distribution of Lepeoptheirus salmonis (Krøyer, 1837) and Caligus elongatus (Nordmann, 1832) on wild sea trout Salmo trutta L. – ICES Journal of Marine Science, 65: 171–173. Lepeophtheirus salmonis (Krøyer, 1837) and Caligus elongatus (Nordmann, 1832) were found on 100% and 90%, respectively, of 30 wild sea trout from the east coast of Scotland. Mean abundances of the same two sea lice were 7.8 and 7.7, respectively. The distribution of the two species of sea louse differed, however, with a greater proportion of L. salmonis in the posterior and anterior dorsal regions, and a greater proportion of C. elongatus in the caudal and posterior ventral regions.

scholarly journals Response of the Sea Louse Lepeophtheirus salmonis Infestation Levels on Juvenile Wild Pink, Oncorhynchus gorbuscha, and Chum, O. keta, Salmon to Arrival of Parasitized Wild Adult Pink Salmon

2006 ◽  
Vol 120 (2) ◽  
pp. 199
Author(s):  
Alexandra Morton ◽  
Rob Williams
Keyword(s):  
Chum Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Primary Source ◽  
Sea Lice ◽  
Oncorhynchus Gorbuscha ◽  
Oncorhynchus Keta ◽  
Lepeophtheirus Salmonis ◽  
Louse Infestation ◽  
Age Cohorts

Recent recurring infestations of Sea Lice, Lepeophtheirus salmonis, on juvenile Pacific salmon (Oncorhynchus spp.) and subsequent annual declines of these stocks have made it imperative to identify the source of Sea Lice. While several studies now identify farm salmon populations as sources of Sea Louse larvae, it is unclear to what extent wild salmonid hosts also contribute Sea Lice. We measured Sea Louse numbers on adult Pink Salmon (Oncorhynchus gorbuscha) migrating inshore. We also measured Sea Louse numbers on wild juvenile Pink and Chum salmon (Oncorhynchus keta) migrating to sea before the adults returned, and as the two age cohorts mingled. Adult Pink Salmon carried an average of 9.89 (SE 0.90) gravid lice per fish, and thus were capable of infecting the adjacent juveniles. Salinity and temperature remained favourable to Sea Louse reproduction throughout the study. However, all accepted measures of Sea Louse infestation failed to show significant increase on the juvenile salmon, either in overall abundance of Sea Lice or of the initial infective-stage juvenile lice, while the adult wild salmon were present in the study area. This study suggests that even during periods of peak interaction, wild adult salmon are not the primary source of the recent and unprecedented infestations of Sea Lice on juvenile Pacific Pink and Chum salmon in the inshore waters of British Columbia.

Growth and ionoregulatory ontogeny of wild and hatchery-raised juvenile pink salmon (Oncorhynchus gorbuscha)

2009 ◽  
Vol 87 (3) ◽  
pp. 221-228 ◽  
Author(s):  
A. Grant ◽  
M. Gardner ◽  
L. Nendick ◽  
M. Sackville ◽  
A. P. Farrell ◽  
...  
Keyword(s):  
Specific Growth ◽  
Pink Salmon ◽  
Sea Lice ◽  
Whole Body ◽  
Oncorhynchus Gorbuscha ◽  
Life History Stage ◽  
Initial Exposure ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Future Studies ◽  
Specific Growth Rates

Juvenile pink salmon ( Oncorhynchus gorbuscha (Walbaum, 1792)) enter seawater (SW) shortly following emergence. Little is known about growth and development during this life-history stage when sensitivity to sea louse exposure may be high, an issue that is of current concern in British Columbia. We tested the hypothesis that growth and ionoregulatory development were similar in hatchery-raised (Quinsam) and wild (Glendale and One’s Point) juvenile pink salmon (measured over 22 weeks) following SW entry. Fish body mass increased from 0.20 ± 0.01 to 6.47 ± 0.37 g, with mean specific growth rates of 2.74% to 3.05% body mass·day–1 among the three groups. In all three groups, gill Na+–K+-ATPase (NKA) activity peaked at 12 µmol ADP·mg protein–1·h–1 following 8 weeks post-transfer to SW. Whole body Na+ and Cl– concentrations, which again did not differ among groups, were highest upon initial exposure to SW (~70 mmol·kg wet mass–1) and declined over time as gill NKA activity increased, indicating that the hypo-osmoregulatory capacity was not fully developed following emergence and initial entry into SW. Thus, consistent with our hypothesis, few differences were observed between hatchery-raised and wild juvenile pink salmon reared under laboratory conditions. These baseline data may be important for future studies in determining the effects of sea lice on wild juvenile pink salmon.

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