scholarly journals Salmon lice evasion, susceptibility, retention, and development differ amongst host salmonid species

2017 ◽  
Vol 75 (3) ◽  
pp. 1071-1079 ◽  
Author(s):  
Samantha Bui ◽  
Elina Halttunen ◽  
Agnes M Mohn ◽  
Tone Vågseth ◽  
Frode Oppedal

Abstract With different ecological characteristics amongst salmonid species, their response to parasitic infestation is likely to vary according to their spatial and temporal overlap with the parasite. This study investigated the host–parasite interactions amongst three species of salmonids and the ectoparasitic salmon louse, Lepeophtheirus salmonis. To determine any variation in infestation parameters amongst salmonids, single population groups of Atlantic salmon (Salmo salar), chinook salmon (Onchorhynchus tshawytscha), and previously-infested and naïve sea trout (Salmo trutta) were exposed to a controlled infestation challenge. We found that chinook salmon and both sea trout groups were more susceptible to acquiring lice than Atlantic salmon. Behavioural responses during infestation were more pronounced in Atlantic and chinook salmon. Parasite development was similar in lice attached to Atlantic salmon and sea trout, but hindered on chinook salmon. At 16 days post-infestation, chinook salmon had reduced lice loads to the same level as Atlantic salmon, whilst sea trout retained their lice. These results demonstrate differences in interactions with L. salmonis amongst these species, and highlight the vulnerability of sea trout to infestation.

2003 ◽  
Vol 60 (5) ◽  
pp. 1139-1148 ◽  
Author(s):  
K.A Glover ◽  
Ø Skaala ◽  
F Nilsen ◽  
R Olsen ◽  
A.J Teale ◽  
...  

Abstract Three Norwegian sea trout (Salmo trutta L.) stocks and a farmed Atlantic salmon (Salmo salar L.) stock were challenged with salmon lice (Lepeophtheirus salmonis (Krøyer, 1837)), in a “common garden” experiment. Sea trout from the River Guddal exhibited a significantly lower level of infection, as measured by louse abundance and louse density, than other stocks. In addition, salmon lice developed significantly more slowly on the Guddal stock than on the other stocks. Salmon louse abundance and density were similar for the Rivers Fortun and Sima stocks of sea trout, and abundance of lice, though not density, was highest for farmed Atlantic salmon. Within stocks, there were no differences in infection levels of salmon louse between mature and immature fish, between sexes, or between anal-fin-clipped and non-clipped salmon. Differences in infection level among the sea trout stocks may, it is suggested, reflect genetic differences.


2015 ◽  
Vol 7 (2) ◽  
pp. 91-113 ◽  
Author(s):  
EB Thorstad ◽  
CD Todd ◽  
I Uglem ◽  
PA Bjørn ◽  
PG Gargan ◽  
...  

1998 ◽  
Vol 76 (5) ◽  
pp. 970-977 ◽  
Author(s):  
Pål Arne Bjørn ◽  
Bengt Finstad

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.


Parasitology ◽  
1999 ◽  
Vol 119 (1) ◽  
pp. 41-51 ◽  
Author(s):  
O. TULLY ◽  
P. GARGAN ◽  
W. R. POOLE ◽  
K. F. WHELAN

Infestations of post-smolt sea trout (Salmo trutta L.) by the salmon louse (Lepeophtheirus salmonis Krøyer) were characterized in 42 estuaries over a 5 year period in Ireland. Spatial variation in infestation was more significant than temporal trends and existed at 3 levels; between regions (regions >100 km of coastline), between bays within regions (bays <50 km in length) and between estuaries within bays (distance between estuaries <10 km). The observed spatial structure in infestations inferred that production of the infective larvae varied between regions and bays and that there was limited movement of fish and infective larvae between regions and bays. In addition the different levels of infestation recorded between estuaries in the same bay indicated short spatial scale variability in parasite transmission. Significantly higher infestations occurred in bays that contained lice-infested farmed salmon. Lice-infested wild spring salmon, which were present in estuaries of some systems, did not have a significant positive impact on infestations.


2017 ◽  
Vol 74 (9) ◽  
pp. 2354-2363 ◽  
Author(s):  
Knut Wiik Vollset ◽  
Elina Halttunen ◽  
Bengt Finstad ◽  
Ørjan Karlsen ◽  
Pål Arne Bjørn ◽  
...  

Abstract Impacts of sea lice (Lepeophtheirus salmonis or Caligus spp.) on wild salmonids is currently one of the most important issues facing management of fish farms in salmon producing countries in the northern hemisphere. Surveillance of sea lice on wild Atlantic salmon (Salmo salar) is often hampered by the ability to catch enough migrating post-smolts. Therefore, sea lice abundance on anadromous trout (Salmo trutta) is often used to infer sea lice abundance on migrating salmon post-smolt. However, the assumption that there is a relationship between the abundance of lice on salmon and trout has never been tested. Here we use a dataset of sea lice on salmon post-smolt and sea trout that have been caught simultaneously in trawl hauls, to evaluate the correlation in abundance of sea lice between the two species using various statistical models. We demonstrate that trout generally has higher abundances of sea lice than salmon. Average lice per gram fish on sea trout (log transformed) predicted the abundance of lice on salmon best. Negative binomial models of lice counts were preferable to using trout lice counts as direct estimates of salmon lice abundance, and they had better predictive ability than logit models of high (vs. low) lice counts. Including the size of the salmon increased the predictive ability of the model, but these data are not generally available. The effect of salmon weight may have been a direct effect of body size, or an indirect effect of time spent in marine waters. Finally, we predict lower salmon lice counts on migrating salmon with our selected binomial model than with the current method of using trout lice counts as a direct estimator on salmon lice counts, and demonstrate that management advice would change considerably depending on the chosen method.


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