Factors Impacting the Mille Lacs Lake Walleye Population

[Vitreus]

My professor invited me to the DNR Roundtable with him on Friday, and I feel obligated to share some of the information here, seeing as how this is where I've gotten some of the best feedback when it comes to fishing advice. I grew up fishing Mille Lacs, caught my first walleye (28" ) on the pond. I hear a lot of speculation about the reasons for the state of the fishery, so I thought I'd provide some data for those of you who care to read. Here are some facts:

1) The walleye population in Mille Lacs lake has been declining since 1999 and it continues to decline. There are now about 1/5 as many male fish and about 1/3 as many female fish. Importantly, the young walleyes (fresh hatched on up to about 12 inches) are experiencing the highest mortality.

2) Water clarity has been increasing since the turn of the century (Secchi is pretty much always >3m at this point)… And it started getting clearer before we had zebra mussels. Most agree that the water clarity increase is a result of better sewage practices. No more fecal fertilizer.

3) Water temperature is increasing. It's increasing everywhere… On Mille Lacs, it's considered the primary culprit for reduced cisco - a staple of the walleye's diet.

4) AIS (spiny water flea, zebra mussels) have gained footing. Studies have shown however, that spiny water fleas are not causing food-web effects that deprive young walleye of food (a gut analysis showed that they are not dying of starvation). And like I said before, zebra mussels can't really be blamed for the Secchi increase, because that trend began before their introduction.

5) Bass, pike, and cormorant populations are going up. They are eating more young walleyes… but, before you start blaming pike (or God forbid muskie, which exist in very low numbers), you should know that adult walleyes eat far more young walleyes than all of these other species…

That brings me back to why. The main reason is probably increased predation (gut analysis of predator fish shows more small walleye consumed which explains why young fish are hit the hardest), but it's not as simple as liberalizing limits on other predators… Because walleyes are the main predator. It is a variety of factors that have come together to contribute to the demise of the Mille Lacs walleye population. First of all, with less ciscos, predators have to resort to other baitfish, and small walleye are now on the menu. Also, with increased water clarity, predators gain an advantage over their prey. At the meeting, someone suggested fertilizing the lake, but this could backfire badly (nasty algae blooms come to mind). And to bring back the ciscos we would need to lower water temps, which would require the reversal of global warming - which is a bit outside the scope of a lake management plan. Really, there's little that can be done, other than reduce bag limits… And to be honest, I do not think that will make a long-term difference. The real problem is not anglers, or netters - it is a changing environment that won't support the same kind of walleye population it used to.

[Hartley]

Once again, Do Nothing Rights FAILED again to admit that they're partially to be blamed. Also, isn't it ironic that many people are catching 10-12" walleye's? The last 2 years we've had late ice outs, and with that the "Tribes" were only able to do minimal netting??? Just my $.02

[maxpower117]

Once again, Do Nothing Rights FAILED again to admit that they're partially to be blamed. Also, isn't it ironic that many people are catching 10-12" walleye's? The last 2 years we've had late ice outs, and with that the "Tribes" were only able to do minimal netting??? Just my $.02

I agree with this but I also believe that if the nets were well managed, we can all have our cake and eat it too.

The DNR seems to have no control over the harvest on this lake and that's their #1 priority.

[FowlSki]

Perch. Baby walleyes are showing up because the perch had a stellar hatch so the big walleyes had something to eat besides baby walleyes.

[Bandersnatch]

Perch. Baby walleyes are showing up because the perch had a stellar hatch so the big walleyes had something to eat besides baby walleyes.

Roger that.

Think slots not nets.

[Getanet]

What's interesting is that perch don't appear to be picking up the slack. The Pioneer Press had an interesting article on the the report yesterday. Here is the section about perch:

Quote:

What puzzles the panel is why yellow perch, a favorite walleye food, hasn't filled the void more.

Yellow perch numbers are high on Mille Lacs, yet it doesn't seem to be curbing walleye cannibalism enough. One guess is that the clearer water has created a "separation" between where walleye like to roam and where perch like to hide: Simply put, maybe the walleye have gone deeper than the perch -- and the proliferation of non-native Eurasian water milfoil weedbeds might be helping perch hide.

To be clear, much of the panel's final report falls somewhere on the spectrum between suspicion and speculation. But there are constellations of evidence suggesting the lake's current state of affairs -- and its current stringent regulations -- aren't a one-off blip that soon will rectify itself with a return to years such as 1992, when anglers could take a record 1.2 million pounds of walleyes.

[northender]

If the netting had not been put into place, the slot limits would not have been put into place per the Mn. DNR--in writing on the record.

What factor, directly, had the most negative impact on the walleye numbers at Mille Lacs? Page 12 of the blue ribbon report suggests management needs to change, validating the extreme slot limits played a huge role in the crash.

No nets == no crash. Netting is the cause. Treaty harvest forced the DNR to change in 1998. No other factor comes close to being a major cause of the crash at Mille Lacs. Treaty harvest is the basis of the whole problem. In so many words, the DNR has said so...based on why they put the devastating slots into place in the late 90's and continue to keep them in place through the present.

And no one knows or will admit to any negative impact the actual nets themselves impact the fish numbers. How can they not play some level of negativity during the spawn? How can gill nets not play a negative role--as they have been banned from game fish harvest for a century?

Slot limits are the main problem as was predicted when they were put into place--now 15 plus years ago.

The nets? One way or another, what you have now would not have happened if they ( the nets) were never put into the Mille Lacs waters.

[northender]

I've stated here before, the "factor" most obvious in regard to the netting impact on walleye numbers itself. Interesting that the blue ribbon boys and all have not spoken to this obvious, based on DNR records, "factor".

When the DNR does a walleye tagging study, they set nets to gather fish to be tagged. On average, over a period of 1-3 years, less than 10 percent of the tagged walleye are caught and sometimes killed by hook and line anglers. (that percentage of dead tagged fish in a year are variable due to slot limits that vary from year to year or lake to lake but would average about 10 percent).

So, based on the fact that tagged walleyes, which are similarly, randomly netted not unlike Treaty Harvest nets, about 90 percent of the Treaty harvest fish each year would NOT be killed the same year by hook and line--the only other major mortality factor. (DNR nets are set in the spring also to gather fish for tagging) That means 90 percent of Treaty harvest fish, which amounts to many 100's of 1000's over the past 15 plus years, would have survived at least one or more springs if not killed by Tribal nets--to spawn, potentially multiple more years than they were allowed to because of Tribal netting. Add that "factor" up over time?

The "experts" say a "dead fish is a dead fish". How can that apply, knowing that a huge percentage of walleyes killed in Tribal nets, would NOT get killed the same year or most likely, for multiple years--if hook and line and natural mortality was the only dead fish "factor" in place?

How can the netting, over a period of years, NOT be an impacting "factor"? Based on actual DNR records of tagged fish that were netted/trapped?

Vitreus? What you say?

[northender]

Vitreus--you and other experts speak about clearer water being an issue and potentially playing a negative role in the YOY survival due to easier predation.

1. Why is there zero history of this "factor", on the record, anywhere in the world--MI.,WI. and Ohio for example) per the zebra mussel studies/history, except Mille Lacs?

2. No doubt, the clearer water adds vegetation. Deeper and more widespread. Per the DNR, for an example, the milfoil in Lake Minnetonka and other places has enhanced the ability for YOY to hide and survive. Since the milfoil hit the scene in these lakes, such as Minnetonka, walleye numbers and other fish species has grown hugely! Why are more weeds in Mille Lacs a bad thing--due to the clearer water? ( clearer water, due to zebra mussels for many years, has created BIGGER numbers of walleyes/creel surveys at Lake Winnebago in WI. for another example--along with huge amounts of more weeds?) Why is clearer water a problem exclusive to Mille Lacs?

You say what Vitreus?

[DTro]

During the Roundtable this year the direct question was asked to Paul V. (who was representing the Blue Ribbon Panel), “how does the tribal netting factor into the equation?”. He simply stated, “there is no significant impact on the overall fishery due the tribal harvest”. Its not a harvest problem. The problem is keeping the fish alive the first few years.

[Getanet]

From what I've read, you have to already have your mind made up that the nets are the main cause of problems in order to draw that conclusion from the report.

[northender]

As my words say, I am NOT saying, the netting harvest by itself is or has been the basis of the problem.

I agree with blue ribbon panel that how the lake is managed and has been managed the past 15 years is the main problem--that has created the predation issues on YOY walleyes.

The fact is though, per the DNR fisheries guys in Aitkin, the ONLY reason they have done what they have done ( slot limits etc.) is to accommodate the Treaty harvest/related court ordered harvest quota's ( that were never mandated in the past). End the netting and the DNR can manage the lake as they had for countless years --trouble free--before the Treat harvest was forced on to the scene. No netting and the blue ribbon guys would have had nothing to study...let alone anything that now needs changing. The netting is the basis for all the problems/changes--per the DNR records--but they will not say it I so many words these days.

But there is no logic, PHD. or not, to back up the theory that the netting has no negative effect. My previous post on Tribal netting/harvesting spawning walleyes, using the tagging studies as a relative basis for my theory, is hard to dispute if you are the DNR--PHD or not. Or anyone with any open minded common sense.

"Harvesting congregated vulnerable spawning walleyes", per the DNR, is not allowed in Minnesota. It is "not good conservation". Bad everywhere but Mille Lacs? Close lakes to harvest in some late springs--but net Mille Lacs the same period of time? Do the math and tell me it has no "significant" negative effect over a period of years--using Tribal harvest numbers in my previous post above.

Simply, as they are schooled to say each spring at a conference at Camp Ripley, the DNR reps will not say the truth on the record. (off the record the Aitkin fisheries guys talk differently) They get schooled each spring on how to speak about the Mille Lacs issues!

[northender]

During the Roundtable this year the direct question was asked to Paul V. (who was representing the Blue Ribbon Panel), “how does the tribal netting factor into the equation?”. He simply stated, “there is no significant impact on the overall fishery due the tribal harvest”. Its not a harvest problem. The problem is keeping the fish alive the first few years.

Of course, Paul V. was the not asked, most likely, if the huge amount of big walleyes was/is the main reason ( the report indirectly says that) the YOY don't survive these days, what was the basis for the past 15 plus years to create the huge amount of predation/big walleye numbers? Would he then say, if asked, "Treaty Harvest pushed us into those slot limits to stay under the unprecedented mandated poundage quota--that was put into place exclusively to accommodate the Tribal netting"? I doubt he would even attempt to answer the question in that form and from that direction...let alone admit to that truth/reality lol

[Getanet]

As my words say, I am NOT saying, the netting harvest by itself is or has been the basis of the problem.

[northender]

I say, per your quote of my words--"no nets--no cause". THAT is exactly what reality is. If the netting had not been put into the scenario at Mille Lacs, the DNR management of the lake would not have changed--according to the DNR records. PERIOD! No netting--no ill-advised slot limits ( per the blue ribbon report that was a mistake and cause) No nets--no predation issues caused by the slot limits...YOY survive as they had been for countless years. Need I say more so you understand my words?

Take away Treaty harvest scenario from the past 15 years and nothing would have changed--per the DNR! That and only that is basis for the crash. And was predicted to be so 15 years ago by the same DNR that manages the lake today--on the record.

[H2O Milfoil]

I don't think anyone would say the netting has "no negative effect." Removing the walleyes by any method is going to have some negative effect.

GetaNet: I agree to an extent. I am old and I was taught by my grandfathers that it is not healthy to a fishery to harvest fish during their spawn. They used restraint and helped craft the rules we live by today. I have seen damage done even to panfish being over-harvested during their spawn.

[David Anderson]

Well I contend that while yes, the total harvest via nets can be figured in and justified the real problem is the post spawn harvest prevents the greatest amount of YOY biomass to be produced. Sure, the claims that the problem isn't with how many walleyes are hatching yet they instantly become food for everything including their parents. If all of the fish were allowed to spawn rather than removing them full of eggs and milt, it could very well provide that extra buffer that would eventually become what is needed to feed the remaining fish without impacting the minimum YOY to maintain a healthy population. Yes, a dead fish is a dead fish but certainly the dead fish with eggs in it is a double wammy, especially when we are all talking about what's eating the small walleyes.

[Getanet]

GetaNet: I agree to an extent. I am old and I was taught by my grandfathers that it is not healthy to a fishery to harvest fish during their spawn. They used restraint and helped craft the rules we live by today. I have seen damage done even to panfish being over-harvested during their spawn.

I agree with you to a large extent. But we're not talking about unregulated harvest during the spawn on Mille Lacs. The netters have a quota that is monitored fairly closely and once its reached the nets come out. The quota for hook-and-line angling is far greater - and those fish that we take from the lake from mid-May through the end of February aren't going to spawn in the spring either.

[northender]

I agree with you to a large extent. But we're not talking about unregulated harvest during the spawn on Mille Lacs. The netters have a quota that is monitored fairly closely and once its reached the nets come out. The quota for hook-and-line angling is far greater - and those fish that we take from the lake from mid-May through the end of February aren't going to spawn in the spring either

[northender]

I agree with you to a large extent. But we're not talking about unregulated harvest during the spawn on Mille Lacs. The netters have a quota that is monitored fairly closely and once its reached the nets come out. The quota for hook-and-line angling is far greater - and those fish that we take from the lake from mid-May through the end of February aren't going to spawn in the spring either.

[SaintPaulPaul]

Read the report with open eyes and you will see a logical connection between factors affecting the lake. Say what you will about the Treaty's ramifications of 15 years ago and mull it over and over in your head and you will begin to believe that that is the only cause. But also look at what else has happened in the last 15 years: Increase in global(water) temp, introduction of invasives (water flea, milfoil, zebra mussels), a huge spike in Northern pike numbers, more efficient methods of fishing (cams, flashers, gps), etc, etc. Obviously, these factors are compounding one another, leading to a declining fishery. There now exists the possibility of the lake NEVER returning to the "glory days"...and even in the "glory days" when I did fish Mille Lacs (longer than 15 years ago) the resort and land owners were blaming the netting for every single aberration in walleye numbers. One word that will become very helpful in the future? ADAPT.

[Bandersnatch]

When the estimated hooking mortality alone is above the quota netted, and then compounded by the rod and reel take, I find it nothing short of ridiculously hypocritical for people that still fish the lake for Walleye to be pointing the finger at anyone but themselves.

You will not convince me otherwise.

[northender]

When the estimated hooking mortality alone is above the quota netted, and then compounded by the rod and reel take, I find it nothing short of ridiculously hypocritical for people that still fish the lake for Walleye to be pointing the finger at anyone but themselves.

You will not convince me otherwise.

Sad but true in a sense. Anglers fished within the DNR rules created to accommodate Treaty harvest. Using your theory, anglers should have stopped fishing walleyes on the lake to accommodate the treaty harvest and therefore not playing a role in crashing the walleye numbers.

Just what sense/reasoning/basis does that now or should that have happened the past 15 plus years?

Should the anglers themselves be blamed or the rules they were forced to play within--exclusively put in place due to the added Treaty harvest aspect? ( confirmed by the blue ribbon report)

[northender]

Read the report with open eyes and you will see a logical connection between factors affecting the lake. Say what you will about the Treaty's ramifications of 15 years ago and mill it over and over in your head and you will begin to believe that that is the only cause. But also look at what else has happened in the last 15 years: Increase in global(water) temp, introduction of invasives (water flea, milfoil, zebra mussels), a huge spike in Northern pike numbers, more efficient methods of fishing (cams, flashers, gps), etc, etc. Obviously, these factors are compounding one another, leading to a declining fishery. There now exists the possibility of the lake NEVER returning to the glory days...and even in the glory days when I did fish Mille Lacs (longer than 15 years ago) the resort and land owners were blaming the netting for every single aberration in walleye numbers. One word that will become very helpful in the future? ADAPT.

*Walleye numbers in other Midwestern lakes, warming to the same levels at the same pace, show nothing like Mille Lacs problems.

* invasive creatures were not in the lake for at least ten years during the time the walleyes numbers showed huge declines per the DNR graphs. ( the blue ribbon reports says they ( invasive creatures) did not play a role in the demise of the walleye numbers)

* DNR studies continue to show the modern day methods only spread the catch out but does not increase the overall harvest numbers. Even legislative studies have been forced onto the scene, dating back to the early 70's with graphs /sonars, and in recent years with the camera aspect, show no increase in overall harvest numbers--only spreading out the catch rates among anglers--taking away the "90 percent of the fish are caught 10 percent of the fishermen" scenario from many years ago.

* why would netting NOT being blamed? It is the exclusive reason the lake was and is being managed differently the past 15 plus years vs. the previous numerous decades.

* yes--open eyes/open minds are key here. Only the facts/records should play a key role in reaching conclusions.

[Getanet]

* yes--open eyes/open minds are key here. Only the facts/records should play a key role in reaching conclusions.

You can't be serious. The report lists a number of factors impacting Mille Lacs that have nothing to do with netting, and you've singled out the netting to be not just a contributing factor - but the biggest factor.

[northender]

You can't be serious. The report lists a number of factors impacting Mille Lacs that have nothing to do with netting, and you've singled out the netting to be not just a contributing factor - but the biggest factor.

[bustumup]

Let's try this a different way. Because of Treaty, slot restrictions are put on walleye to slow the harvest to stay in quota. Slot is put on size fish that are least populated, therefore nobody can catch a keepable fish (there are not many in lake to catch). Those walleye grow larger & are still protected, pretty soon the lake is overrun with large fish that cannot be harvested & they consume way more forage which throws the lake into imbalanced state. Way too many large fish (not only walleye) that are eating all the YOY & not allowing them to reach a keepable size.

TREATY--->QUOTA--->SLOT--->TOO MANY LARGE FISH--->YOY GET CHOWED.

LAKE IS IMBALANCED & WILL STAY THAT WAY, ONLY THING DNR WILL DO IS CLOSE IT TO SPORT ANGLERS & LEAVE IT FOR TRIBES TO CONTINUE NETTING & SPEARING. See ya bye!

[DTro]

Here's the one factor to that equation that is missing. The overwhelming majority of of a walleyes diet is perch and tulibee.

If those 2 species were unavailable, then its probably a good possibility they turned to the small walleyes. Keep in mind the diet study didn't show that.

If all that is true though , then it wasn't the netting that caused the ultimate crash, but rather the mismanagement of the lake.

[Bandersnatch]

From the horses mouth

“And yet the population has been reproducing at high levels throughout this period and into the present,” Venturelli said. “The young just aren’t making it through. This is likely the result of walleye predation, and to a lesser degree, recent predation by pike and cormorants.”

Possible explanations for higher predation include fewer tullibee for larger walleye to feed on, improved water clarity and quality since the Clean Water Act of the 1970s and the possible effects of invasive species."

[Getanet]

Here's the one factor to that equation that is missing. The overwhelming majority of of a walleyes diet is perch and tulibee.

If those 2 species were unavailable, then its probably a good possibility they turned to the small walleyes. Keep in mind the diet study didn't show that.

If all that is true though , then it wasn't the netting that caused the ultimate crash, but rather the mismanagement of the lake.

Can you expand on that DTRO? From what I've read the lack of tulibees are from warmer water temps. I've also read a lot of reports on this site and HSO that people are seeing plenty of perch on their cameras.

If both or either of those things are true, how do we reverse those trends?