Growth on Broad Whitefish (C. nelsonii)

Observation: Norma Ballot was fishing this spring and caught a broad whitefish that had a growth or as she described 'blood clot' on its dorsal fin. Other fish were also caught with a similar condition in Selawik. This is an important issue as river conditions are changing in the Selawik River and we are concerned about the health and safety of our fish. Susan Clark, for Norma Anallaq Ballot.

Alaska Department of Fish and Game Consult: Dr. Ted Meyers, Fish Pathologist writes, "This whitefish has a black growth associated with the dorsal fin- probably a neoplasm (cancer). The black color suggests a melanoma originating from cells (melanophores) normally found in the skin or fin that contains black melanin pigment. The hemorrhaging on the anterior of the fish is likely from trauma, especially if the fish was caught in a net. Take a look at our field guide regarding neoplasms in fish. A diagnosis from only a photo has its limitations. If more affected fish are caught, a fresh/unfrozen fish should be submitted on gel ice to our Anchorage fish pathology lab for a complete examination to more accurately diagnose the lesion." Pathology Laboratory: Phone: (907) 465-3577. Alaska Department of Fish & Game Pathology Section Division of Commercial Fisheries, P.O. Box 25526 Juneau, AK 99802-5526-Ted Meyers

LEO says: according to the ADF&G Field Guide, a number of factors can contribute to cancer in fish including viruses, environmental chemicals, repeated physical trauma, age, sex, genetics, and health of the fish's immune system. Although the growth looks scary it does not pose a human health risk. Cancer like this in fish is usually a rare event effecting only one fish in several thousand. If it is occurring more frequently than the question is whether some kind of environmental condition is harming the fish and whether it poses a risk to people. LEO Network recommends continued monitoring of the fish harvest in Selawik.