I sent this photo to Dave V and asked him if this Gill Lice was a serious threat. This was his response: 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 [email protected] I have another email out to Dave asking if the gill lice can be transferred by an angler to another stream on gear/net/waders. Will update when he responds.