Short-term temporal variation in inshore/offshore feeding and trophic niche of Atlantic salmon Salmo salar off West Greenland

2019 ◽  
Vol 610 ◽  
pp. 191-203 ◽  
Author(s):  
HJ Dixon ◽  
JB Dempson ◽  
M Power
2021 ◽  
Vol 9 (4) ◽  
pp. 703
Author(s):  
Deborah Vargas ◽  
Eva Vallejos-Vidal ◽  
Sebastián Reyes-Cerpa ◽  
Aarón Oyarzún-Arrau ◽  
Claudio Acuña-Castillo ◽  
...  

Piscirickettsia salmonis, the etiological agent of the Salmon Rickettsial Septicemia (SRS), is one the most serious health problems for the Chilean salmon industry. Typical antimicrobial strategies used against P. salmonis include antibiotics and vaccines, but these applications have largely failed. A few years ago, the first attenuated-live vaccine against SRS (ALPHA JECT LiVac® SRS vaccine) was released to the market. However, there is no data about the agents involved in the activation of the immune response induced under field conditions. Therefore, in this study we evaluated the expression profile of a set of gene markers related to innate and adaptive immunity in the context of a cellular response in Atlantic salmon (Salmo salar) reared under productive farm conditions and immunized with a live-attenuated vaccine against P. salmonis. We analyzed the expression at zero, 5-, 15- and 45-days post-vaccination (dpv). Our results reveal that the administration of the attenuated live SRS LiVac vaccine induces a short-term upregulation of the cellular-mediated immune response at 5 dpv modulated by the upregulation of ifnα, ifnγ, and the cd4 and cd8α T cell surface markers. In addition, we also registered the upregulation of il-10 and tgfβ. Altogether, the results suggest that a balanced activation of the immune response took place only at early times post-vaccination (5 dpv). The scope of this short-term upregulation of the cellular-mediated immune response against a natural outbreak in fish subjected to productive farm conditions deserves further research.


2015 ◽  
Vol 72 (7) ◽  
pp. 2139-2148 ◽  
Author(s):  
Vanessa Minke-Martin ◽  
J. Brian Dempson ◽  
Timothy F. Sheehan ◽  
Michael Power

Abstract Otolith-derived estimates of mean marine temperatures used by West Greenland 1SW Atlantic salmon (Salmo salar) of North American origin were determined for fish collected in 2009 and 2010. Otolith material corresponding to the second summer at sea was subsampled, via micro-milling, and analysed by mass spectrometry to produce stable oxygen isotope (δ18O) values from which temperature use estimates were obtained from a salmonid-based fractionation equation. Mean temperature estimates did not differ significantly by period (early vs. late summer), or capture year. The mean and variation estimates were also consistent with temperature use values previously published in the literature or derived from the limited number of data storage tags that have been retrieved for Atlantic salmon, with 80% of all individuals occupying temperatures in the 3.9–9.7°C range. Among-individual differences in temperature use did not correlate with measured otolith growth zone widths. Given the temporal, spatial and methodological variation associated with the derivation of marine temperature use estimates for Atlantic salmon, the data were interpreted to define a range of preferred temperatures within which among-individual differences in growth were driven by the interaction of feeding and temperature use, possibly as a result of the opportunistic feeding behaviour known to predominate among Atlantic salmon.


2005 ◽  
Vol 62 (4) ◽  
pp. 808-817 ◽  
Author(s):  
J.L. Thorley ◽  
D.M.R. Eatherley ◽  
A.B. Stephen ◽  
I. Simpson ◽  
J.C. MacLean ◽  
...  

Abstract The potential utility of rod catch and automatic fish counter data as measures of Atlantic salmon (Salmo salar) abundance in Scottish rivers was assessed. The trend (long-term) and residual (short-term) variation in the net annual count for 12 counters were compared with the trend and residual variation in either the annual or spring (February–May) rod catch, as appropriate, for the fisheries district in which the counter is located. Trends were fitted using a cubic smoothing spline and compared using reference bands. In eight of the 12 short-term comparisons, the residuals were significantly correlated. The four incongruent short-term comparisons involved the shortest time-series (≤12 years) or lowest rod catches. In eight of the 12 long-term comparisons, the trends fell within the reference bands in 50% or more of the years. Rod catch and counter data both contain useful information about Atlantic salmon abundance, albeit on different temporal and spatial scales, which should be integrated into assessment schemes.


1988 ◽  
Vol 45 (8) ◽  
pp. 1330-1339 ◽  
Author(s):  
D. M. Blouw ◽  
S. D. Saxon ◽  
E. M. P. Chadwick

The assumption is generally made in stock identification studies that variation within stocks is not confounded with variation among them. To evaluate whether this assumption is tenable we test the null hypothesis of temporal stability in five key meristic traits of a single stock of Atlantic salmon (Salmo salar). We used smolts collected over a 10-yr period in the downstream migrations from one small river system. Individuals were tagged when captured and preserved, so we can estimate variability within, as well as among, runs. The meristic traits are remarkably homogenous within runs and cohorts. However, the null hypothesis of stability over time among runs and cohorts is strongly rejected for each trait. We conclude that temporal variation is both extensive and persistent. There is limited covariation among the traits, but they are largely independent of scores of environmental variables and of variation in the biological attributes of the stock. Because among-group variability is meaningful only in context of within-group variation, and because the within-group variation is large, our results have serious implications for sampling design in stock identification studies.


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