Lake Pepin/Pool 4 Update from Walleye Searchers Meeting

Hello all,

Sorry for the delay getting the presentation out this year. We decided to split it into two sections this time. Attached here you will find a PDF containing the quick Lake Pepin/Pool 4 update I provided at the February 5th, 2018 Walleye Searchers Meeting in Rochester as well as the answers to some of the questions I received prior to the presentation.

I also presented some information related to MN DNRs efforts with the WI DNR and now the IA DNR as well to carry out a review of border water regulations. We have been working on that portion of the presentation, and I hope to have it posted to IDO by the end of the week. It hopefully contain a bit more information than the one presented on the 5th, but we didn’t want to hold the update portion of the presentation any longer.

As always feel free to contact me directly with any questions.

Thanks for your interest,

Nick

Attachments:

1. 

   Walleye-Searcher-2018-Presentation-w-notes-sheet.pdf
   

Because the notes sheet version of the presentations sometimes make it difficult to see the individual slides I am attaching another version that uses a feature of adobe that is new to me.

This attached file contains exactly the same information as the one above, but the slides will show up as a full (landscape oriented page). To see the speaking notes and explanations I include with each slide you should look for a small text balloon (like in a comic strip) in the upper left hand corner of each page. Hovering a mouse over this or tapping it on a smartphone or tablet should open a popup window over the slide containing the notes.

If folks have trouble with this feature please let me know and I will go back to using the other format exclusively.

Nick

Attachments:

1. 

   Walleye-Searcher-2018-Presentation-w-notes-layer.pdf
   

Thanks Nick!

BOFFFF = Big Old Fat Fecund Female Fish
I dont know why but that made me chuckle..

Thanks for sharing the report Nick, there is some surprising findings in there

gonecribbin wrote:

BOFFFF = Big Old Fat Fecund Female Fish
I dont know why but that made me chuckle..

I did as well when I was reading it.

Great stuff. Thank you for sharing.

My Conclusions from the Report & Time on P4:

-walleye and sauger samplings don’t show any drastic changes (up or down) in numbers for recent year classes
-consistently high water in April & through May = a good thing
-higher shad #’s can make for more difficult fishing, but that’s the reason P4 fish aren’t scrawny (compare a 24″ fish from Mille Lacs to one from P4; the river fish could nearly eat the other)
-pike samplings support what I see (tons of 20-30″ fish caught in the last year)

I enjoy reading these reports and seeing how they compare to what I saw last year on P4. Is the lack of a representation of the 2016 class a concern for future years? Will the lack of fish in that class lead to changes in the regs or because it is just one year can it work itself out? Also, I’m curious if anyone knows why the Sauger class in 2016 was much better than the Walleye class? or did I read that wrong.

Not trying to cause any regulation controversy I’m just curious if I am understanding this correctly and like to learn. Can the average angler like myself use this information to keep a more targeted class of fish and help the future of P4?

The poor year class will likely be noticeable in the size structure of Walleye anglers encounter for the next few years. Each year there will be a size class that is harder to catch (this year probably 10″-12″, next spring probably 13″-15″ fish). As the fish age growth between sexes and other year classes bordering the 2016 year class will likely make it harder to detect.

A single year class would not trigger any regulations, but that being said we are proposing a review of the border water regulations that we hope will begin later this spring (opportunities for public comment will be announced by press release and I will try to post them here as well).

We are still only one year into the evaluation of the 2016 year class so numbers may change a bit as more data comes in, but the difference between the 2016 Walleye and Sauger production may be related to their preferred spawning habitats on Pool 4. A previous study found that Walleye seem to prefer flooded terrestrial vegetation for spawning and therefore need the higher spring water levels I referred to in the presentation. Sauger on the other hand tended to use main channel border areas, that are unlikely to become dewatered during a dip in the hydrograph like we saw in April of 2016.

With regard to targeting a certain class of fish…
I view this information largely as a way to help anglers understand what to expect, and what might be driving trends we as scientists and managers see in the data. The reality is that while you could use this information to select fish to harvest from particularly abundant groups, the very abundance of those sizes make them proportionately more likely to be caught and harvested in many cases.

Thanks for the questions

Nick

The second half of the presentation dealing with regulations on the MN/WI border waters has been posted here:

Border Water Review

Thank You for putting this up did they ever find out why the Shad die off?

There was no definitive determination of a cause for the Gizzard Shad die off. As I have mentioned before during a typical winter most of the young of year Gizzard Shad die in the Pool 4 system. They are not well adapted to cold water, and if you use a camera while ice fishing (especially in some of the boat harbors) during mid to late winter it is not uncommon to see the bottom littered with dead shad. One of the likely contributing factors may have been an early ice out followed by another cold snap. That added amount of stress may have been the straw that broke the camel’s back.

We often see outbreaks of various infections in fish during particularly stressful periods (heat, cold, spawn, low oxygen, etc). Just like people when a fish is stressed its immune system is more likely to let infections through, and when that stress is related to things like the ones I mentioned above there is often a crowding element (fighting for a small area with enough oxygen for instance) that leads to rapid spread of whatever takes hold.

When you say Walleyes in Pepin prefer vegetation Is that thru out the whole watershed as the southern end has more rock structure. Is the vegetation part because there is not enough rock gravel spawning areas?

When looking at the Lake part of Pepin being it is mostly sand are there very many areas in the main lake that the Walleye do spawn? Would you know if the Walleyes in the lower part of the lake migrate down the Lake say to the Chippewa river to spawn or backwater areas around Nelson and such?
Just pumping you for more information really have to say Thank You for taking the time to answer questions.

Thanks for the questions Tom. I sent you a PM addressing some of them, but much of the specific information we have on spawning locations and movement of Walleye for Lake Pepin and Pool 4 comes from a MN DNR Investigational Report done in the late 90s. I have included a link to the MN DNRs investigational report page, and to the specific Investigational Report (#481) below.

http://www.dnr.state.mn.us/publications/fisheries/investigational_reports.html

http://files.dnr.state.mn.us/publications/fisheries/investigational_reports/481.pdf