Gill Lice: What & Where

I have always been a curious individual. Sometimes this trait instigates issues, a good part of the time I never find what I am looking, and every so often it teaches me a vast amount about an uncommonly interesting subject. Below are some pictures with accompanying information that I hope will promote discussion.

Gill Lice is an aquatic parasite that, in the adult stage, is apparent in the form of small, whitish tubular growths throughout the gills and mouth of infected fish. There are different species of gill lice and resultingly have different species of host. Gill Lice—is it awful? Should we be worried? The short answer: it depends on the species under attack and where in the United States one is located. Apparently, Great Lakes Steelhead (Lake-run Rainbow Trout for those that feel particularly sensitive to the Commonwealth’s use of ‘steelhead’) do just fine with Gill Lice. Brook Trout cannot endure with Gill Lice & in addition to serious concern surrounding climate change, Pennsylvania’s State Fish now has to battle a near-invisible enemy. There is a plan in action for trying to contain Gill Lice in Pennsylvania. There are a few PowerPoints and articles available on the department website. I have read what is available and I akin their attempts to our department of agriculture’s attempts to stop the Emerald Ash Borer or even the Woolly Adelgid—ultimately unsuccessful. All in all, they have documented Gill Lice in nearly every Erie County Steelhead stream.

If any of readers have further questions regarding the protocol for handling fish with confirmed Gill Lice, please feel free to enquire by calling the PA fish and Boat Fish Health Unit at (814) 353-2223.

For those curious, such as myself, you can still consume a Steelhead with Gill Lice and it is the same health advisory provided by the P.F.B.C.— “Trout stocked from Pennsylvania Fish and Boat Commission state fish hatcheries are subject to the blanket one-meal-per-week consumption advisory that applies to recreationally caught sport fish in Pennsylvania (Commonwealth of Pennsylvania Public Health Advisory 2021 Fish Consumption).”  

Below are pictures of two Steelhead Trout that suffered from Gill Lice. Both fish were legally harvested, smoked, and consumed.

Note the tan nodules near the tongue, on the roof, and down the throat. Those are Gill Lice.

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