In our zoo medicine class, we learned about the fishing industry and many of its unsustainable and environmentally damaging practices. The problem that stands out most to me is what salmon have been going through in recent decades, whether the populations are those near Chile or Canada. Inappropriate open-ocean salmon farming practices have led to a steep decrease in wild salmon populations worldwide.
Infectious Salmon Anemia (ISA) is caused by a virulent strain of an orthomyxovirus of the genus Aquaorthomyxovirus that is related to influenza viruses. ISA, first described in Norwegian fisheries in 1984, has decimated Atlantic salmon (Salmo salar) populations in many countries that engage in commerce in the Atlantic Ocean. There is a concern for Pacific salmon populations! The fish are infected via virus entry through the gills, skin, or pectoral fins, leading to epithelial lesions and, later on in the disease progression, endothelial cells. Clinical signs include hemorrhage from the eyes and skin, pale gills, and ascites. The invasive spread of pathogens such as ISA virus through its accumulation in waters in which salmon populations reside is in large part due to large shipping vessels. Ships, unfortunately, serve a role in spreading ISA and other waterborne diseases such as cholera. A study out of Scotland documented a correlation between coastal well boat traffic in shipping live fish or visiting harvesting sites and outbreaks of ISA. The origin of the virus could be infected ballast water from processing plants or harvest stations.
I’m a big fan of eating salmon but have been rethinking my choice of favorite fish as of late.