Open gates and Walleye

Recently IDO member gbfan10 posted a question about the effect of open gates at Lock and Dam 3 on Walleye population to the board. (see link below)

Gates at dam open Pool 4

He also got in touch with me via e-mail to ask a similar question and wanted to post my response. I told him I would put together a post containing figures that explained the concepts a bit better than my e-mail response and would post it for him.

Thanks for the interest in the river gbfan10, hopefully the attached pdf addresses your question.

As always feel free to contact me if you have any questions.

Nick

Attachments:

1. Open-Dam-Effects-on-Pool-4-Walleye-Population.pdf

Good read, thank you!

Thank you for posting the Information!!

Mwal

Great read, learned a lot. Thanks for your work!

Excellent pdf! I like seeing data like this laid out so clearly and explained this well. Thanks

Great read Thanks
Mike

Thanks for your well laid out presentation Nick.

I applaud your willingness to take the time to put this together and post this!

I do have a question now that I’ve read through the PDF a couple of times.

Last fall we had a very short fall bite compared to years past. It seemed to end in December when the rollers were raised. I understand that we’re talking about catch rates here and there’s many factors like angler experience and fishing memories in play here.

My question is about non spring flooding and the gates being open. Wouldn’t the walleyes/sauger move up stream into the next pool far easier when the rollers are opened and the flow is between 36k and 45k cfs?

After I read the report my first thought was—- we are losing more walleye to Pool 3 by the fish that go up the Vermillion and into Pool 3 than any that make it through the dam. Walleye like certain types of grass to breed and the backwater areas of the Vermillion are probably the best breeding location after the reworking of the Wisconsin shoreline by the dam. Once a fish gets up the Vermillion, Pool 3 is not great challenge to get to and the current is MUCH less than running the dam. Of course, many a tournament has been won by guys fishing the drop back spots on the Vermillion after the spawn when the fish head back to Pool 4 and the lake.

Here’s some more light reading for you BK. A report on asian carp swimming speeds since we are talking about open gates and velocities.

Attachments:

1. ansrp12-3-Asian-Carp-Swimming-Velocity.pdf

Someone else just completed ACarp Swimming Velocity testing. Interesting read…now off to convert cm/s to cf/s.

There is additional information on this topic in the link included in the post below.

https://www.in-depthoutdoors.com/community/forums/topic/river-species-information/

Taken from Nick’s link above…

Extensive creel and netting surveys conducted by the Minnesota Department of Natural Resources was
summarized by Thorn (1984). Thorn found that walleye abundance 15 years after opening a continuous
season was similar to walleye abundance when the fishery had a season closure. He found the spring fishery
produced 16.4% of the pressure and 17.3% of the walleye harvest.

Thorn noted that May and June actually
accounted for much of the yearly harvest (43.3%). No trend was detected in the average weight of the
harvested walleye, ranging from 1.43–1.76 pounds, over the 15 years (Thorn 1984).
During the late 1980s, management objectives for the UMR walleye fishery focused on Maximum Sustained
Yield (MSY) and an increase in the quality of the walleye harvested. Walleye populations were modeled in
several UMR pools and were used to predict changes to the walleye fishery under a length limit restrictions.

Very good read!!

Now I have to read the rest of it!

I know, I know. Old info. But I’m willing to bet not much has changed.