Q: I was walleye fishing on a kettle lake between Lake Joseph and Georgian Bay last summer and after we landed a few fish I noticed some kind of flesh-eating disease on the right cheek of one of the fish. Otherwise, it was very healthy looking, but I have never seen this before. Have you? What is it? Is it safe to eat? If I catch one like this again, am I to let it go, or is it a sign of a bigger problem and should be destroyed?
– Matt Klymenko, MacTier
A: OFAH fisheries biologist Adam Weir responds: I touched base with Dr. Véronique LePage, a fish pathologist from the University of Guelph, and the quality of the images did not allow her to confirm or deny the presence of gill copepods/gill lice, but mentioned that the eroded operculum (gill cover) can be due to old or ongoing gill disease.
In Ontario this is most commonly attributed to bacterial gill disease, nodular gill disease, or columnar is, or maybe a result of other things like genetics, trauma, etc. It is possible that this fish was compromised from previous disease, leaving it with a shortened operculum. However, there’s nothing really conclusive from just the image.
To answer your other questions, the fish is most likely safe to eat. If you catch one like this again, and are legally allowed to keep it, refer to the Guide to Eating Ontario Fish for consumption recommendations. The issue is likely not part of a bigger problem, and the fish should not be destroyed. It is illegal to abandon fish or permit the flesh to spoil, if the fish is suitable for human consumption.
Dr. Véronique LePage
Fisheries Pathologist at the University of Guelph
(via Ontario Federation of Anglers and Hunters Fisheries Biologist Adam Weir)
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Originally published in Ontario OUT of DOORS’ 2020 Fishing Annual.