Gill Lice?

[spinner1]

what do all of you know about gill lice?

I have heard bows and brooks can get them and it can decimate the entire population.

Does anyone know anything about them?

[aged_sage]

I know just enough about them to get myself into trouble, but will share my limited knowledge and then posit an answer to your fundamental question. They are blood suckers, which in and of itself says to me, at least, that they aren't good for the fish. I think it would be safe to say that under certain circumstances, they could become so prevalent on the gills of a fish that they could cause death of an individual fish. By extension, it is conceivable that they could become so abundant as to to cause a decline in a fish population.

A close analogy is the occurrence of mosquitoes in such vast numbers in a coastal county in Texas not too many years ago that they actually sucked enough blood from both cows and horses as to result in the death of a large number of cows and a few horses.

In both instances, it would not be expected to be a common occurrence, but is it possible? Yes. Did the gill louse infestation reach such proportions that they decimated a population? I cannot say with certainty. A definitive answer might be found by Googling the subject.

aged sage

[spinner1]

An email back from the local fish manager

Len,

It is unlikely gill lice will destroy all of the brookies in **** Creek although I have seen infestations that were heavy enough (**** Creek, Monroe Co.) to interfere with the fish's respiration leaving them vulnerable if dissolved oxygen levels are reduced. The infestations seem to worsen when fish are stressed (low water levels or high water temps) but may totally disappear when conditions are good. We are aware of the problem and will continue to monitor but there is little that can be done (the only good way to remove gill lice from fish is with a formalin dip).

Dave

David Vetrano
Fisheries Supervisor
3550 Mormon Coulee Rd.
La Crosse WI, 54601
608-785-9009
David.Vetrano@dnr.state.wi.us

[spinner1]

I have another email out to him about if the infestation can be carried on your gear to another stream.

[aged_sage]

In the biological world, all things are possible! However, I seriously doubt that they would survive for more than just a few hours at most if they got on your gear. Also, it is unlikely that they would get on your gear to begin with. The challenges that any individuals so transported and arrive in a viable state would be faced with in their attempt to find a new host would be formidable. Although possible, the odds would be greatly against this happening. My personal experience with gill lice has been in marine/estuarine situations where the vastness of the environment pretty much precludes such concerns.

Under your scenario, I totally agree with what your state fisheries biologist said.

aged sage

[spinner1]

thanks aged sage

A local fish manager gave me the same exact response?
Are you a retired fish manager?

[spinner1]

Len,

Anglers should get in the habit of disinfecting their waders, shoes and landing nets that touched stream water or fish before they move from one stream to another to prevent transfer of a variety of diseases and parasites. We use a 1% bleach solution to rinse off our waders and electrofishing gear before we move from stream to stream when we are doing fish surveys (a small spray bottle works well for waders). If you're not going to fish for awhile, letting your gear dry completely can also be effective (most aquatic parasites cannot tolerate dessication).

Dave

David Vetrano
Fisheries Supervisor
3550 Mormon Coulee Rd.
La Crosse WI, 54601
608-785-9009
David.Vetrano@dnr.state.wi.us


Gill Lice ONLY effect tigers/brookies/bows from wisconsin. Did not ask about non-wisconsin species.

[aged_sage]

spinner:

I have advanced degrees in marine zoology, and have worked briefly as a marine fisheries biologist; but have tried to keep my fingers "on the pulse" of things aquatic since my youth. Yes, I am also retired; and I highly recommend it!

aged sage

PS: David is right on with his comments about disinfection of gear. My only additional comment is that diatoms (rock snot) are apparently not always adversely affected by even 10% bleach! But then they are not parasites either.