Gill Lice

Hi Len,

Thanks for the updates you send. My fall field projects are underway, and I’m looking forward to see how the trout populations we monitor have held up with the hot and dry summer. I’m expecting to see lower water levels (we collect hourly water level data on a number of streams) and possibly correspondingly lower abundances and sizes of trout.

I want to bring to your attention our new effort to collect data from anglers on gill lice presence/absence in Wisconsin trout streams. We recently were awarded a DNR Citizen-Based Monitoring grant to set up a website to collect angler observations. The “we” is me, Sue Marcquenski, Matt Kreuger and Laura MacFarland (River Alliance of Wisconsin) and Kim McCarthy (Trout Unlimited). The website is hosted by TU and is now up and running:

http://wisconsintu.org/gilllice

I don’t think there is a link yet to the gill lice page from the wisconsintu.org home page, but there should be soon. For now you have to use the above direct link.

If you have any personal observations, feel free to either enter them online or send them directly to me. I’m currently monitoring gill lice infection rates in a number of trout populations, and any information we get from anglers may help in expanding our research.

Feel free to pass along the information on our new effort to collect angler observations on gill lice. There will be an article in the upcoming issue of Wisconsin Trout as well, and we’ll re-publicize the project before the start of the 2013 trout season.

Thanks,

Matt

Matthew G. Mitro, Ph.D.
Coldwater Fisheries Research Scientist
Wisconsin DNR, Fisheries and Aquatic Sciences Research Section
Science Operations Center, 2801 Progress Rd.
Madison, WI 53716
608-221-6366 phone
608-221-6353 fax
[email protected]

email to Matt Mitro TODAY:

I am wondering about stocking brook trout in streams with know Gill Lice infections?

Would it not only make sense to NOT put healthy brook trout in infected streams?

Any stocking should be done in streams with NO reported infections?

Maybe brown trout should be stocked again?

Len Harris

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Matt’s response

Len,

These are all important questions. I don’t think we have the data yet, however, to adequately answer all of these questions right now.

Host density (brook trout in this case) is a significant factor in whether or not gill lice become epizootic (infection rates rising to epidemic proportions). But it is likely not the only factor. We are trying to figure out what those other factors are.

Brown trout co-occurring with brook trout may be an important factor. One hypothesis is that brown trout may be effecting locally-high densities in brook trout. That is, brown trout may be pushing brook trout into locally-higher densities than may have occurred otherwise had brown trout not been present. If that is the case, then that would be one more reason not to stock brown trout on top of brook trout if we desire to keep brook trout in the stream.

The questions you raise are another reason why we need to compile data on gill lice presence and absence. Until we have those data, we cannot adequately implement such a stocking strategy.

Matt

http://dnr.wi.gov/news/Weekly/?id=368#art3