"Grayling guts with unknown pearl like cyst or tapeworm. Never seen this before in our grayling."

From the images shared, these appear to be Philemona, a freshwater parasite. Philomena is a food quality concern but is Not considered a human health concern. With proper preparation, the salmon is safe to eat.

The parasite Kudoa is causing trouble for the fishing industry in the southern hemisphere. By chance, researchers found the scary parasite in coastal cod from the Helgeland coast.