Are viruses keeping sea lice at bay in wild salmon?

July 6, 2023
Sea lice on a juvenile salmon. Hakai Institute.

Read the UBC Science article: Are viruses keeping sea lice at bay in wild salmon?

More than 30 previously unknown RNA viruses have been identified in sea lice, parasitic copepods (small crustaceans) that have been implicated in the decline of wild salmon populations and causing problems to the fish aquaculture industry worldwide.

This research, recently published in PLOS Pathogens, was carried out by Dr. Tianyi Chang, Dr. Brian Hunt, Dr. Curtis Suttle from the Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia and Dr. Junya Hirai from the Atmosphere and Ocean Research Institute, University of Tokyo.

The researchers obtained and analyzed RNA data from sea lice removed from out-migrating juvenile salmon collected in the waters surrounding the Discovery Islands and Broughton Archipelago on the northeastern side of Vancouver Island, as well as from farmed salmon in Chile.

The paper sheds greater light on the types of viruses being carried by sea lice, and how the viruses and host are interacting. “We found many more types of viruses than are known in sea lice or their distant relatives; the lice are mounting an immune defense response to many of these viruses indicating that they are replicating,” says Dr. Curtis Suttle, senior author of the paper. “In a natural system, viruses may prevent explosions in sea-lice populations by rapidly replicating when densities become high.”

Read/Listen to the Cortes Currents interview with Dr. Curtis Suttle: The viruses infecting sea lice

Read the paper: Divergent RNA viruses infecting sea lice, major ectoparasites of fish