Contents

May 2021
Vol 7, Issue 22

About The Cover

Cover image expansion

ONLINE COVER Aquaculture, along with large-scale agriculture, has been known to spark the emergence of novel diseases, which may be transmitted to nearby wildlife populations. However, even though viral pathogens such as piscine orthoreovirus-1 (PRV-1) present a threat to endangered wild salmon populations, the role of aquaculture in the spread of the virus to wild fish populations has remained unclear. To better understand how aquaculture may have facilitated the spread of the virus to wild salmon in the Northeast Pacific, Mordecai et al. combined all publicly available genomic sequences of PRV-1, dating back to 1988 and including 86 newly sequenced genomes from Northeast Pacific populations. Through phylogenetic analyses, the researchers found that PRV-1 may have spread from Atlantic aquafarms to those in the Pacific, which in turn spread the virus to wild salmon populations. The findings suggest that a lineage of the virus in the Northeast Pacific diverged from the same lineage in the Atlantic Ocean in 1989, predating the first report of disease from the virus in 2002. This indicates that PRV-1 was introduced to the Northeast Pacific around the same time salmon farms in the region imported Atlantic salmon eggs from Europe. [CREDIT: YVA MOMATIUK AND JOHN EASTCOTT]