Unusual cysts in grayling

Observation by Crystal Frank Welker:

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

LEO Network Says:

Thanks Crystal for your observation. We are sharing with the Alaska Department of Fish and Game, Fish Pathology team. They may be able to help us determine what these area.

Comment from Jayde Ferguson:

These do look like parasites cysts, probably larval tapeworms. Here's a link to the chapter in our booklet that provides more information and for the fish and human health concerns. I've also included a line to a similar resource from Yukon as that's a nearby area where these have been observed in the past too.

https://www.adfg.alaska.gov/static/species/disease/pdfs/fishdiseases/diphyllobothrium.pdf

https://yukon.ca/sites/yukon.ca/files/env/env-yukon-fish-health-handbook.pdf pg. 30-33

Comment from Noah Tsigonis:

“The CDC recommends cooking fish to 145°F for 5 minutes or freezing fish at -4°F for 7 days to kill worm parasites. It is important to note that most home freezers are only set to 0°F and DO NOT meet the CDC freezing recommendations. Because of the variability of temperatures within home freezers and the usual lack of a temperature readout, we do not recommend home freezing as a reliable method of killing the parasite. Take care when smoking or cooking fish to ensure the entire fish reaches 145°F for at least 5 minutes. Light smoking or drying are NOT adequate to kill the parasite.

If you see this or any other odd phenomenon, please reach out to the LEO network. For members in the TCC region, please also contact OEH@tananachiefs.org”