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3. Lampetra fluviatilis ?

Attached to the back of this poor little Brown is what I believe to be Lampetra fluviatilis.

Falsifly,

Where did you find this blood-sucking parasite? I believe that L. fluviatilis is a European river lamprey. If the unfortunate brownie is from WI, this might be Icthyomyzon unicuspis (the silver lamprey) or I. castaneus (the chestnut lamprey).

Thank you Gonzo,
I’m glad I entered the ? in the title. After a little bit of research, following your lead, it appears that you are quite correct. The two: Ichthyomyzon unicuspis and I. castaneus are so closely related in all respects, other than the common name associated with color, that I first assumed I. unicuspis. However, from the few photographs I was able to pull up on the internet, my photos and recollection streamside, I am in doubt as to which.

According to my log entries this is the third trout taken from the Namekagon since 1995 in which the “blood-sucking parasite” was attached.

I would caution anyone from deducing the seemingly rare occurrence of this event, for one must first catch more than a few fish to apply any significance to occurrence. Ha!

Yeah, the silvery belly made me think this might be unicuspis, but according to distribution information on the WI DNR website, castaneus is probably the more likely species in the Namekagon.

I have caught several trout over the years with those blood-sucking lampreys on their side. I can recall spotting those silvery devils stuck to the side of feeding trout as well. Although it has been sometime since I have seen one in the Namekagon. I was hoping the dams on the St.Croix and lower Namekagon were helping block them from getting into the upper Namekagon any more. I guess I was wrong.

Hi John,

I'm not sure how dams might affect indigenous river-dwelling lampreys other than making the populations disjunct. I suppose it's even possible that dams on the lower river sections might have the effect of depleting populations below the dams simply by depriving them of spawning habitat.

In any case, indigenous lampreys are reported to have little effect on fish populations. Of course, the "gross-out" factor remains. Apparently, fish feed on lamprey eggs and on the larvae as they drift downstream before burrowing in the mud. It's nice to know that the fish get something out of this relationship other than just holes rasped in their sides by these wretched vampires. Kinda makes me wonder if "ammocoete" imitations might be worth a try at the right time of year on the Namekagon....(?)

It seemed like there were a lot more lamprey around in the mid-80s. The past few years I can't recall seeing many and I thought I had read some where about dams, lamprey traps, or something that were helping stop the migration of lampreys up the St.Croix, but I could be wrong.

BTW, the lampreys on the Namekagon seem like dwarfs compared to the eels I saw on the Delaware River. :)

I work for Sea Lamprey control out of Marquette, MI and I showed one of my co-workers that more experience with native lamprey's these pictures and he IDed this lamprey as a Chestnut lamprey (Icthyomyzon castaneus ). He said he could just make out the modeling toward the tail that he has seen in the chestnut. He also says this river eventually flows into the Mississippi River and chestnuts are fairly common in this system.

Toga,
Thank you for the response.

Nice

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Just above, another blood-sucking parasite? A spammer?