Deformed Whitefish (C. nelsonii)

Observation: In front of St. Mary's AC Store, an (otherwise) nice looking white fish (Coregonus nelsonii) that had a bulged out eye ball on one side of head and on the other it has some type of growth around the cheekbone. Would like to know the cause of these observed abnormalities to the fish as this is an important subsistence food source that a part of our diet.

Alaska Department of Fish and Game Consult: Dr. Ted Meyers, State Fish Pathologist writes, "I see the exophthalmia (popeye)," Meyers explains, "but there is no photo showing the growth on the other side of the head. Popeye is generally caused by osmoregulatory problems with ion balance that can be caused by several issues including infection, trauma and neoplasia (cancer). Supersaturation of oxygen or nitrogen gas in the water column can also cause bulging of the eyeballs."

Resource:

• Tammy Davis, Project Leader, Invasive Species Program, ADF&G, provides a "How to Report an Invasive Species" website.

LEO says: Seeing an occasional fish appearing like this is probably not unusual, although certainly worth posting as a LEO observation. If however, you observe several fish with the same condition, we would begin to question if there is some kind of illness or environmental cause that would require investigation.