Low-level pathogen transmission from wild to farmed salmonids in a flow-through fish farm

Abstract While the potential effects of pathogens spread from farmed fish to wild populations have frequently been studied, evidence for the transmission of parasites from wild to farmed fish is scarce. In the present study, we evaluated natural bacterial and parasitic infections in brown trout (Salmo trutta m. fario) collected from the Černá Opava river (Czech Republic) as a potential source of infections for rainbow trout (Oncorhynchus mykiss) reared in a flow-through farm system fed by the same river. The prevalence of bacterial and protozoan infections in farmed fish was comparable, or higher, than for riverine fish. Despite this, none of the infected farmed fish showed any signs of severe diseases. Substantial differences in metazoan parasite infections were observed between wild and farmed fish regarding monogeneans, adult trematodes, nematodes, the myxozoan Tetracapsuloides bryosalmonae found in riverine fish only, and larval eye-fluke trematodes sporadically found in farmed fish. The different distribution of metazoan parasites between brown and rainbow trout most probably reflects the availability of infected intermediate hosts in the two habitats. Despite the river being the main water source for the farm, there was no significant threat of parasite infection to the farmed fish from naturally infected riverine fish.

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Sensory quality and consumers’ acceptance towards wild and farmed brown-trout (Salmo trutta) and farmed rainbow-trout (Oncorhynchus mykiss)

BRAZILIAN JOURNAL OF FOOD TECHNOLOGY ◽

10.1590/1981-6723.10419 ◽

2020 ◽

Vol 23 ◽

Author(s):

Ana Maria Antão-Geraldes ◽

Sílvia Rafael Hungulo ◽

Etelvina Pereira ◽

Amílcar Teixeira ◽

Alfredo Teixeira ◽

...

Keyword(s):

Rainbow Trout ◽

Brown Trout ◽

Salmo Trutta ◽

Sensory Quality ◽

Farmed Fish ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Consumer Panel ◽

Brown Trout Salmo Trutta ◽

Sensory Qualities ◽

Degree Of Acceptance

Abstract The present study aims to compare the sensory qualities and the degree of acceptance of wild/farmed brown-trout (Salmo trutta) and the farmed rainbow-trout (Onchorynchus mykiss) by a consumer panel. Acceptability regarding attributes appearance, taste, texture, and global appreciation were evaluated on 20 wild brown-trout, 20 farmed brown-trout and 20 farmed rainbow trout by a consumers’ panel formed by 74 elements. Although the panel of consumers equally well accepted all samples, the rainbow trout had classifications slightly higher in all sensory attributes. This tendency was confirmed by internal preference maps performed for each studied attribute. Consumers’ slightly higher preference for farmed fish might indicate that farmed trout could be an alternative to wild brown trout.

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Recirculation versus flow-through rainbow trout laboratory Flavobacterium columnare challenge

Diseases of Aquatic Organisms ◽

10.3354/dao03487 ◽

2020 ◽

Vol 139 ◽

pp. 213-221

Author(s):

C Birkett ◽

R Lipscomb ◽

T Moreland ◽

T Leeds ◽

JP Evenhuis

Keyword(s):

Rainbow Trout ◽

Environmental Parameters ◽

Cumulative Effects ◽

Flavobacterium Columnare ◽

Replacement Rate ◽

Bacterial Concentration ◽

Water Replacement ◽

Dose Concentration ◽

Flow Through ◽

And Control

Flavobacterium columnare immersion challenges are affected by water-related environmental parameters and thus are difficult to reproduce. Whereas these challenges are typically conducted using flow-through systems, use of a recirculating challenge system to control environmental parameters may improve reproducibility. We compared mortality, bacterial concentration, and environmental parameters between flow-through and recirculating immersion challenge systems under laboratory conditions using 20 rainbow trout families. Despite identical dose concentration (1:75 dilution), duration of challenge, lot of fish, and temperature, average mortality in the recirculating system (42%) was lower (p < 0.01) compared to the flow-through system (77%), and there was low correlation (r = 0.24) of family mortality. Mean days to death (3.25 vs. 2.99 d) and aquaria-to-aquaria variation (9.6 vs. 10.4%) in the recirculating and flow-through systems, respectively, did not differ (p ≥ 0.30). Despite 10-fold lower water replacement rate in the recirculating (0.4 exchanges h-1) compared to flow-through system (4 exchanges h-1), differences in bacterial concentration between the 2 systems were modest (≤0.6 orders of magnitude) and inconsistent throughout the 21 d challenge. Compared to the flow-through system, dissolved oxygen during the 1 h exposure and pH were greater (p ≤ 0.02), and calcium and hardness were lower (p ≤ 0.03), in the recirculating system. Although this study was not designed to test effects of specific environmental parameters on mortality, it demonstrates that the cumulative effects of these parameters result in poor reproducibility. A recirculating immersion challenge model may be warranted to empirically identify and control environmental parameters affecting mortality and thus may serve as a more repeatable laboratory challenge model.

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Emergence of Discocotyle sagittata (Monogenea: Polyopisthocotylea) in rainbow trout ( Oncorhynchus mykiss ) and brown trout ( Salmo trutta ) in an Austrian aquarium

Journal of Fish Diseases ◽

10.1111/jfd.13470 ◽

2021 ◽

Author(s):

Eva Lewisch ◽

Hans‐Peter Führer ◽

Bita Shahi‐Barogh ◽

Josef Harl ◽

Mansour El‐Matbouli

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Brown Trout ◽

Salmo Trutta ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Brown Trout Salmo Trutta

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Intra-variability of some biochemical parameters and serum electrolytes in rainbow trout (Walbaum, 1792) bred using a flow-through system

Heliyon ◽

10.1016/j.heliyon.2021.e06361 ◽

2021 ◽

Vol 7 (2) ◽

pp. e06361

Author(s):

Francesco Fazio ◽

Concetta Saoca ◽

Gioele Capillo ◽

Carmelo Iaria ◽

Michele Panzera ◽

...

Keyword(s):

Rainbow Trout ◽

Biochemical Parameters ◽

Serum Electrolytes ◽

Flow Through

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Multi-Approach Assessment for Stress Evaluation in Rainbow Trout Females, Oncorhynchus mykiss (Walbaum, 1792) from Three Different Farms during the Summer Season

Animals ◽

10.3390/ani11061810 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1810

Author(s):

Paul Uiuiu ◽

Călin Lațiu ◽

Tudor Păpuc ◽

Cristina Craioveanu ◽

Andrada Ihuț ◽

...

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Biochemical Parameters ◽

Principal Component ◽

Environmental Parameters ◽

Blood Parameters ◽

Summer Season ◽

Farmed Fish ◽

Blood Profile ◽

Blood Biochemical

Blood biochemistry parameters are valuable tools for monitoring fish health. Their baseline values are still undefined for a multitude of farmed fish species. In this study, changes in the blood profile of rainbow trout females (Oncorhynchus mykiss) from three farms were investigated using different biomarkers during the summer season. In the given context, the main water physicochemical parameters were investigated and twelve biochemical parameters were measured from blood samples of rainbow trout reared in the Fiad, Șoimul de Jos, and Strâmba farms. We selected these farms because the genetic background of the rainbow trout is the same, with all studied specimens coming from the Fiad farm, which has an incubation station. Forty-five samples were collected monthly (May to August) throughout summer to observe the changes in the blood profile of rainbow trout. Principal component analysis showed a clear separation both among the studied farms and months. Furthermore, significant correlations (p < 0.05) between the majority of the biochemical parameters were found, indicating that the environmental parameters can influence several blood parameters at the same time. The present study provides several useful norms for assessing the welfare of rainbow trout, indicating that the relationships among different parameters are important factors in interpreting the blood biochemical profiles.

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