Impact of abiotic factors and husbandry on saprolegniosis in salmonid farms

Perla Tedesco*, Marcia Saraiva, Jose Vladimir Sandoval-Sierra, Mickael Teixeira Alves, Roberta Galuppi, Javier Dieguez-Uribeondo, Pieter van West, Alastair Cook, Paulette Posen, Birgit Oidtmann, Marialetizia Fioravanti

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Oomycetes of the genus Saprolegnia are widespread in freshwater environment and are among the main pathogens causing economic losses in salmonid aquaculture. Infections by mycotic agents in fish farming are generally considered to result from chronic stress and poor fish condition associated with water quality problems, adverse environmental conditions, frequent/rough/incorrect handling, concurrent infections, physiological changes associated with reproduction and immunocompromised animals. To identify risk factors for Saprolegnia infections in trout and Atlantic salmon farming, longitudinal studies were carried out in different Italian, Spanish, and Scottish fish farms. Prevalence of saprolegniosis and fish mortality were monitored over time and statistically analysed with respect to husbandry and environmental factors. Overall, statistical results by production cycle (trout vs salmon farming) and by country indicate that the prevalence of Saprolegnia may be influenced by peculiarities of the culture system and farming environment. Nevertheless, a specific set of parameters, including lower water temperature, and handling procedures increased Saprolegnia prevalence in all the considered farms. Particularly, in trout farms Saprolegnia infections represented an important contribution to mortality, and prevalence was influenced by water temperature and pH, and by fish density within the tanks. Similarly, temperature and water quality were the main factors influencing the prevalence of Saprolegnia in Atlantic salmon farms. Moreover, molecular analyses confirmed the role of S. parasitica as the main pathogenic oomycete in trout and salmon farming in the considered countries. The identification of risk factors for introduction and increase of Saprolegnia infection in fish farms will allow the correct design of biosecurity and pathogen control strategies.

Original languageEnglish
Article number738679
Number of pages10
Early online date4 Aug 2022
Publication statusPublished - 15 Dec 2022

Bibliographical note

Funding Information:
This work was financially supported by the EU H2020 [ H2020-SFS-10a-2014 (ParaFishControl, grant agreement No. 634429) (PT, MS, RG, JD-U, PvW, BO & MF)], the BBSRC [ BB/P020224/1 (MS & PvW) & BB/M026566/1 (MS & PvW)] and the University of Aberdeen (MS & PvW). The authors would like to thank all the fish farmers/staff and colleagues who collaborated in the fieldwork and provided valuable information for the study.

Publisher Copyright:
© 2022 The Authors

Data Availability Statement

Research data are shared as supplementary material


  • Aquaculture
  • Atlantic salmon
  • Risk factors
  • Saprolegnia
  • Saprolegniosis
  • Trout


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