“Pathogen exchange is almost inevitable”

Outside the controlled environment of the cultivation centers, salmonids consider free life, a category that covers native, naturalized, asshole and escaped fish.

Unlike culture salmonids, little is still known about viral infections that affect wild populations, which generates an important lagoon in the understanding of ecological effects derived from the interaction between aquaculture and natural ecosystems.

For this reason, a group of Chilean scientists published a study where they conducted a bibliographic review that summarizes information about viruses that infect free life salmon, with the ultimate goal of better understanding the threat they represent both for native fish populations and cultivation fish.

Specifically for the case of Chile, the review mentions that IPNV has been detected almost in all naturalized and escaped salmon, including the SALMON Species of the Atlantic, Salmon Coho, Rainbow Trucharis and common trout.

The above based on a study conducted by the IFOP between 2010 and 2021, where almost 42,000 samples of free life salmon and native fish were analyzed, showing prevalence rates of the IPNV of 2.23% in the Altic Salmon, 2.23% in Coho Salmon, 11.17% in rainbow trout and 24.02% in the common trout.

In the same way, the study mentions that PRV has been detected in archíris trout and naturalized coho salmon, as well as in Atlantic salmon, rainbow trout and escaped coho salmon.

Bidirectional transmission

Dr. David Tapia, a researcher at the University of Chile and the Millennium Invasal nucleus, and who is also one of the authors of the study, tells Salmonxpert that among the main findings of the review stand out that, at global level, there are more reports of viral infections in native wild salmon, followed by escaped crop salmon, where the most reported species would be Salmo salar, Oncorhynchus does not y S. tructand the most common viruses are IHNV, PRV, IPNV and ISAV.

“Literature shows a bidirectional transmission between cultivation salmon and free life populations, which emphasizes the need for monitoring and preventive measures,” explains Dr. Tapia.

“Indeed, free life diseases can represent a threat to salmoniculture. Since both groups share the same environment (for example, the water column), the exchange of pathogens is almost inevitable. Cultivation fish can contract viruses from wild populations, and, in turn, infected fish that escape can act as vectors and propagate pathogens,” adds pathogens, “adds pathogens,” adds pathogens, “adds pathogens,” adds pathogens, “adds pathogens, expert.

However, with respect to the transmission of pathogens from cultivation salmon to native fish, the scientist points out that there are few studies in Chile. As an example, it raises the cases of Piscirickettsia salmonis y Caligus rogercresseyiwhere bacteria has been reported in native species such as Eleginops maclovinus (Robalo), Odontesthes regia (sea pejerrey), SEBASTES CAPSISIS y Australis salilotaand the parasite has been detected in O. Regia y E. maclovinus.

Cases similar to other salmoniculture pathogens such as IPNV, Flavobacterium psychrophilum y Renibacterium salmoninarumwhich have also been reported in native species.

Although this information was not included in the review since it was focused on viral diseases, the expert of the University of Chile states that specifically viral diseases “represent an important threat to salmonids, both cultivation and wild, and the intensive conditions of aquaculture facilities create a crop broth conducive to the appearance and spread of these pathogens. The consequences of the consequences of the transmission of viral diseases between viral disease Cultivation and wild highlight the urgent need to improve management strategies, preventive measures and surveillance activities. ”

Read the abstract del estudio titulado “Viral Pathogens in Free-Living Salmonids: Aquaculture and Ecosystem Implications”, aquí.