The issue of sea lice and their effects on Pacific Coast wild salmon is an endless source for media and news stories. It is common to come across debates about how harmful they are, whether the farms on the coast are the cause of their increasing numbers, not to mention the ongoing debate about whether open or contained farming cages should be used. After reading many articles, and reviewing some of our previous blog posts, I came to realize that I didn’t really know much about the salmon louse and what it is they actually do to fish. So I thought, maybe there are some other equally uninformed people out there who might want to understand a little more about this celebrity creature at centre stage of some B.C. fisheries’ largest debates. Here is what I learned.
Sea lice are naturally occurring in our ocean waters and are transported with the tides. As they are parasitic, once they encounter a fish they will attach themselves to their skin, fish, or gills and feed off them. Usually, the louse will feed from the blood, skin, and mucous of the host fish. Adult salmon with a natural number of sea lice on them, are generally unharmed by these creatures, as they can’t cause much damage to a larger fish. And commonly the younger fish aren’t targeted like the adults are. It is when an over-population of sea lice occurs that there can be problems in our waters. When this takes place, the juveniles become prey as well. Because they are much smaller, they may not be able to cope, and the damage the sea lice may be fatal. This leads, in turn, to declines in salmon populations.