Bacterial infections of Chinook salmon, <i>Oncorhynchus tshawytscha</i> (Walbaum), returning to gamete collecting weirs in Michigan

Microparasites play an important role in the demography, ecology and evolution of Pacific salmonids. As salmon stocks continue to decline and the impacts of global climate change on fish populations become apparent, a greater understanding of microparasites in wild salmon populations is warranted. We used high-throughput, quantitative PCR (HT-qRT-PCR) to rapidly screen 82 adult Chinook salmon from five geographically or genetically distinct groups (mostly returning to tributaries of the Fraser River) for 45 microparasite taxa. We detected 20 microparasite species, four of which have not previously been documented in Chinook salmon, and four of which have not been previously detected in any salmonids in the Fraser River. Comparisons of microparasite load to blood plasma variables revealed some positive associations between Flavobacterium psychrophilum, Cryptobia salmositica and Ceratonova shasta and physiological indices suggestive of morbidity. We include a comparison of our findings for each microparasite taxa with previous knowledge of its distribution in British Columbia.

Section: Bacteriamentioning

confidence: 99%

A survey of microparasites present in adult migrating Chinook salmon (Oncorhynchus tshawytscha) in south‐western British Columbia determined by high‐throughput quantitative polymerase chain reaction

Bass

Hinch

Teffer

et al. 2017

“…For example, immunosuppression by R. salmoninarum in chinook salmon ( Oncorhynchus tshawytsch a) is thought to facilitate infections with pathogenic motile Aeromonas spp. (Loch, Scribner, Tempelman, Whelan, & Faisal, ). Atlantic salmon previously infected with L. salmonis have also shown increased susceptibility to Loma salmonae (Mustafa et al, ) .…”

Section: Discussionmentioning

confidence: 99%

Impact of co‐infection with Lepeophtheirus salmonis and Moritella viscosa on inflammatory and immune responses of Atlantic salmon (Salmo salar)

Carvalho

Whyte

Braden³

et al. 2020

This study was conducted to determine the effects of a co‐infection with Moritella viscosa at different exposure levels of sea lice Lepeophtheirus salmonis in Atlantic salmon (Salmo salar). M. viscosa (1.14 × 106 cfu/ml) was introduced to all experimental tanks at 10 days post‐lice infection (dpLs). Mean lice counts decreased over time in both the medium lice co‐infection (31.5 ± 19.0 at 7 dpLs; 16.9 ± 9.3 at 46 dpLs) and high lice co‐infection (62.0 ± 10.8 at 7 dpLs; 37.6 ± 11.3 at 46 dpLs). There were significantly higher mortalities and more severe skin lesions in the high lice co‐infected group compared to medium lice co‐infected group or M. viscosa‐only infection. Quantitative gene expression analysis detected a significant upregulation of genes in skin from the high lice co‐infection group consistent with severe inflammation (il‐8, mmp‐9, hep, saa). Skin lesions retrieved throughout the study were positive for M. viscosa growth, but these were rarely located in regions associated with lice. These results suggest that while M. viscosa infection itself may induce skin lesion development in salmon, co‐infection with high numbers of lice can enhance this impact and significantly reduce the ability of these lesions to resolve, resulting in increased mortality.

“…salmonicida infections in Great Lakes Chinook salmon (Loch et al . ; Diamanka et al . ) and may be related to the fact that gravid females invest more energy towards gamete production than do males (Brett ).…”

Section: Discussionmentioning

confidence: 99%

Isolation and characterization of Flavobacterium columnare strains infecting fishes inhabiting the Laurentian Great Lakes basin

Faisal

Diamanka

Loch

et al. 2016

Self Cite

Flavobacterium columnare, the aetiological agent of columnaris disease, causes significant losses in fish worldwide. In this study, the prevalence of F. columnare infection was assessed in representative Great Lakes fish species. Over 2000 wild, feral and hatchery-propagated salmonids, percids, centrarchids, esocids and cyprinids were examined for systemic F. columnare infections. Logistic regression analyses showed that the prevalence of F. columnare infection varied temporally and by the sex of the fish, whereby females had significantly higher prevalence of infection. A total of 305 isolates of F. columnare were recovered. Amplification of the near complete 16S rRNA gene from 34 representative isolates and subsequent restriction fragment length polymorphism analyses demonstrated that all belonged to F. columnare genomovar I. Phylogenetic analysis of near complete 16S rRNA gene sequences also placed the isolates in genomovar I, but revealed some intragenomovar heterogeneity. Together, these results suggest that F. columnare genomovar I is widespread in the Great Lakes Basin, where its presence may lead to mortality.