Pink Salmon (Oncorhynchus gorbuscha) with White Nodes/Lumps

Observation by Carol Fletcher:

These pink salmon have white nodes/lumps in their bodies throughout the meat.

Comments from LEO Editors:

We forwarded Carol's observation to Ted Meyers, State Fish Pathologist with the Alaska Department of Fish and Game (ADF&G).

Ted Meyers writes:

These white cysts are likely Henneguya but they are somewhat larger than the usual pea or tapioca size lesion. Cysts in general are better diagnosed by breaking them open--if a white, milky fluid oozes out (parasite spores), then it is likely Henneguya. However, the larger nodules could also be containing tapeworm cysts, instead, a plerocercoid larva that would be visible only if the cysts were opened.

Carol Fletcher responds:

Thank you so much! These fish, there were 4 of them, were caught in Tolstoy Bay (Prince of Wales Island) yesterday. I will pass this info on to the people who harvested them.

Comments from LEO Editors:

According to the ADF&G guide on Diseases of Wild and Cultured Fishes in Alaska, Henneguya is a parasite found in anadromous, marine, and freshwater fish species worldwide. The good news is that it's well-tolerated by infected fish and it doesn't have a negative impact on human health.

This guide also tells us that there are 3 species of larval Tapeworms commonly found in Alaskan salmon (Diphyllobothrium ditremum, dendriticum, and nihonkaiense), and an additional 3 found in other fish species in the state. As long as larval numbers are low, the host fish should be fine; however, juvenile fish are less tolerant and more likely to die from severe infestations.

Apparently, parasitic worms, like tapeworms, aren't new to Alaska. However, our ability to test and identify them has improved. Additionally, the increase of fish importation has allowed for the introduction of a specific species, Diphyllobothrium nihonkaiense. Source: KTUU article on tapeworms in Alaska.

The Alaska Department of Health and Social Services (DHSS) webpage on infectious parasitic worms provides great information on the various types found in the state based on species and on the hosts that they infect, required reporting, and additional resources for the general public and healthcare professionals. Their fact sheet on Diphyllobothrium informs on how those specific tapeworms are spread, symptoms of infection, treatment, and prevention. DHSS warns against eating raw or undercooked fish unless properly frozen (putting on ice for shipment is not sufficient); otherwise, it should be cooked thoroughly. See the fact sheet for guidelines on proper freezing and cooking times and temperatures. Sarah Ingram