Fish are shrinking

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It does.

Fish in the BWCA are definitely shrinking (or, more accurately, average size is decreasing and/or size distribution has changed w/ fewer big fish). Still enough big ones out there to make it fun, exciting, and challenging, but average overall size (especially of pike and lake trout) has decreased a lot. Walleyes, too, especially on the easily accessed lakes near entry points.

Probably an unavoidable element of (relatively) easy access wilderness fishing, but there are still lots of big ones out there, especially a few portages in.

On the plus size, the smallmouth and largemouth seem to be doing very well indeed. I've been especially (pleasantly) surprised by the number of tanker largies I've seen in recent years.

Most fish in the BWCA grow very slow in the infertile water and yes lake trout especially just inside the BWCA have gotten much smaller, and walleye in like the Kawishiwi river are extremely over fished. I wish because it is a wilderness area smaller limits and special regs to maintain quality but still allow a fish diner.
Smallmouth species have spread throughout the BWCA these last two decades and usually most are catch and release.
Black Crappie numbers in Basswood have exploded in size and number this last 10 years. Comparable to anywhere in the state. A real sleeper and unknown to most people up there.

There is a common misconception, typically with anglers who fish near populated areas, and where waters are naturally or artificially more fertile, that the BWCAW is all pristine, lightly fished lakes and streams.
Some native trout lakes only produce a half pound of fish per acre per year, so even light angler harvest can impact the fishery.

Think about lakes like Polly, Ensign, Brule, and Disappontment that have most of their campsites occupied all summer, and a steady harvest of fish almost daily. It adds up. Even big lakes like Basswood are probably impacted by harvest---at least in terms of size structure.

Obviously, every lake is different, and some lakes can sustain relatively heavy harvest (especially for smallmouth bass), but fishing pressure is definitely impacting the area's fish size and numbers---and this is reflected by the fact that fisheries are healthier, and fishing generally better, in Quetico than in the BWCAW.

A century ago, they would have been nearly identical.

I agree with Pinetree that the BWCAW should have a different set of regulations aimed at maintaining more natural distribution of fish sizes and excellent opportunities for large fish.

I wish bass were never introduced to these waters. I much prefer the native species.

I have not read that article. But as to fishing getting smaller from overfishing, my understanding is that wildlife management like MN DNR puts limits on the number and size of fish harvests and regulate depending on how healthy the population is. If there is overharvesting, they will drop the creel limit and institute slot limits. If there are too many fish in a lake, fish can get smaller due to less food to go around. If the bass size is getting larger and walleye’s are getting smaller, maybe they should increase bag limits on bass. I have no problems eating smallmouth, my friends and I find them delicious. We specifically target smallies and have a fish fry twice a week when we’re up there. A walleye thrown in is a treat, but my friends swear they can’t tell the difference. Wish we could take more home, especially if they’re stunting walleye population. But pike eat smallies, so they shouldn’t be affected by smallie numbers; indeed, if smallies are more abundant, pike should be getting larger since they eat them too. So, what’s the reason fish are shrinking in the BWCA? Is it truly overfishing? Then DNR should do something about it, change the regulations. I was just in Basswood 2 years ago and caught the largest numbers and sizes of smallies in the 8 times I’ve been there. Almost all catch and release except two 15 inchers per person to eat that night. Threw all egg laden females back. Are you saying they’re shrinking in all lakes in the BW or just the ones that are more easily accessed?

Pinetree: I wish because it is a wilderness area smaller limits and special regs to maintain quality but still allow a fish diner.

Do that many people bring fish home from their trip? I just dont know how cutting daily limits would impact it that much? I could keep 6 walleyes a day but I cant eat 6 walleyes a day.

Here is the article if you cant view it.

There’s something fishy going on in the water. Across Earth’s oceans, fish are shrinking — and no one can agree why.

It’s happening with salmon near the Arctic Circle and skate in the Atlantic. Nearly three-fourths of marine fish populations sampled worldwide have seen their average body size dwindle between 1960 and 2020, according to a recent analysis.

Overfishing and human-caused climate change are decreasing the size of adult fish, threatening the food supply of more than 3 billion people who rely on seafood as a significant source of protein.

As fish get smaller, there is less meat to cook per catch. So scientists are working to piece together why exactly fish respond to rising ocean temperatures by getting smaller.

“This is a pretty fundamental question,” said Lisa Komoroske, a conservation biologist at the University of Massachusetts at Amherst. “But we still don’t understand why.”


“How is it that we’ve known about this for so long but we don’t understand mechanisms?” she added.

The incredible shrinking fish
One undisputed reason so much marine life is getting smaller is fishing. Recreational anglers and commercial fishers alike like to catch large fish. That quest for the big ones leaves the small fries behind.

Rick Stuart-Smith, a marine biologist at the University of Tasmania in Australia, has surveyed coral reefs around the world. He said he can tell if a protected area has suffered from illegal fishing by the small size and sometimes even the shyness of the fish he sees while diving.

In truly protected areas “you’ll even see big fish in less than ideal habitats,” he said.



But there are plenty of marine species that face little fishing pressure that are still shrinking. To investigate why, Komoroske and her colleague, Joshua Lonthair, decided to grow their own fish.


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The pair started their experiment on sardines in California until the pandemic closed the lab in 2020. “We get a call that the facility is shutting down at midnight,” Lonthair said. “I’m in the lab actually taking my final measurements on those fish for our first set of measurements.”

The pair restarted their work in Massachusetts with about 400 brook trout reared for up to eight months in tanks. The scientists kept some of the fish in waters set at 59 degrees Fahrenheit while others at 68 degrees Fahrenheit. All were fed the same diet.

By the end of the experiment, the difference was stark. The trout raised in warmer waters were on average less than half the size as the other fish.

“You look at the fish, it’s so obvious,” Komoroske said. “Not that you don’t need statistics, but they’re clearly different sizes.” In the ocean, the phenomenon is so widespread it has a name: the temperature-size rule.

Putting theory to the test
For years, the leading theory for why fish grow to smaller adult sizes in warmer waters had to do with their gills.


Fish, unlike humans, cannot regulate their body temperature well. So when the water temperature goes up, so too does the oxygen they require. But, some scientists thought, the limited surface area of fish gills couldn’t keep up with the extra demand of a bigger body, leading fish to cut their growth short.

“That is the crucial point,” said Daniel Pauly, a marine biologist at the University of British Columbia who developed what today is called gill oxygen limitation theory. “Gills don’t go as fast as volume.” Climate change wasn’t on his mind at all when he began developing the theory in the 1970s when studying tiny tropical fish.

But more recently, when Komoroske and Lonthair dissected the brook trout, they found the gills of the fish raised in warm water were more than large enough to meet the animals’ energy needs, according to a study published earlier this year. In the case of the brook trout, the leading theory for why fish were shrinking appeared to be wrong.


A wild brook trout. (iStock)
“It doesn’t matter which species we do it on,” Lonthair said. “If it’s a global theory that the gills are going to limit growth, it shouldn’t matter if it’s a brook trout or a sardine or any other species.”


But Pauly said there is a different way of interpreting the data on the metabolic rate that shows gills do limit growth, and that other studies of the gills of other fish support his theory, too. He added that other scientists attempting to refute his long-standing theory are trying to “harpoon a big whale.”

Komoroske said her team is not trying to “pick fights” with their research. “This is how science is supposed to work,” she said.

‘It’s a problem’
Figuring out exactly why fish shrink in warmer waters is key for helping managers prevent overfishing in the warming open ocean and for helping aquaculturists choose the right fish to farm.

“We’re blinded to fixing problems if we don’t understand what’s causing them in the first place,” said Timothy Clark, a professor at Deakin University in Australia who has conducted similar experiments on fish and temperature.

Other explanations are that fish have evolved to stay small to survive hot spells, or that some other body system besides gills is limiting oxygen uptake and growth.


Salmon at Katmai National Park in Alaska. (iStock)
Whatever the reason, the shrinking-fish phenomenon could refashion ecosystems. “In marine and other aquatic ecosystems, size determines whether you are a prey or predator,” said Asta Audzijonyte at the University of Tasmania, who also studies fish size.


Smaller fish can produce fewer eggs, potentially altering ecosystems as ocean temperatures rise. For those who depend on the sea for their livelihoods, all those smaller fillets fetch a lower price.

“It’s a problem for the fishery,” said Art Bloom, a salmon fisherman in Alaska’s Bristol Bay with more than three decades of experience. “They don’t present as well in the supermarket.” During his career, he has had to switch from using nets with 5¼ inch openings to ones with 4¾ inch openings as the salmon he caught got smaller.

But there are signs of ecosystem health. Inês Martins, an ecologist at the University of York in England who found that nearly three-fourths of marine fish were dwindling in size, said many of those same species are increasing in abundance even as average body sizes goes down.

“There’s always a few winners and losers,” she said.

This article is part of Animalia, a column exploring the strange and fascinating world of animals and the ways in which we appreciate, imperil and depend on them.

Do that many people bring fish home from their trip? I just dont know how cutting daily limits would impact it that much? I could keep 6 walleyes a day but I cant eat 6 walleyes a day. "

You can’t keep 6 walleyes a day, you can only have 6 in your possession at any time. 4 in the freezer and 2 in your possession or any combination of those numbers. Creel limit of 6.

basswoodlakefan: "Do that many people bring fish home from their trip? I just don't know how cutting daily limits would impact it that much? I could keep 6 walleyes a day but I can't eat 6 walleyes a day. "

You can’t keep 6 walleyes a day, you can only have 6 in your possession at any time. 4 in the freezer and 2 in your possession or any combination of those numbers. Creel limit of 6. "

I understand the difference between daily and possession. You could keep 6 walleyes a day if you ate them that day. Which is why I brought up a daily limit. How many people are eating 6 walleyes a day? Or save fillets for the next day?

cwallace: "

basswoodlakefan: "Do that many people bring fish home from their trip? I just don't know how cutting daily limits would impact it that much? I could keep 6 walleyes a day but I can't eat 6 walleyes a day. "

You can’t keep 6 walleyes a day, you can only have 6 in your possession at any time. 4 in the freezer and 2 in your possession or any combination of those numbers. Creel limit of 6. "

I understand the difference between daily and possession. You could keep 6 walleyes a day if you ate them that day. Which is why I brought up a daily limit. How many people are eating 6 walleyes a day? Or save fillets for the next day?"


Maybe the MN DNR has that info

The article references the brook trout study - the warmer group, was right at the upper limit of where they die. Makes sense they were smaller. The fish were stressed, at temps that are near death for them. It would be interesting to see if there's a statistically significant difference if they only increased the temp by 2 degrees.

I mean - at that point why not increase the temp to boiling - look they didn't grow at all. The fact that they brough it to near the upper limit for where brook trout can survive, kind of negates the study for me. I think they needed five groups, one near the lower limit, so just above freezing, one at ideal, a group 2 degrees below, a group 2 degrees above and the group near the upper limit. So in the case of the salmon fishery they reference, is it it a few degree warmer temp or over-fishing? Is there an area, where the temp was previously near thier lower limit of prefered water temp and is now thriving?

I would also be interested to see how a few degree increase in temps affects warmer water species? I mean LMB grow alot larger in southern states.

One other thought - nearly all state record fish continue to be broken. Larger and larger fish continue to be caught. There's a few older records out there, but mostly they're being broken.

Speckled:

One other thought - nearly all state record fish continue to be broken. Larger and larger fish continue to be caught. There's a few older records out there, but mostly they're being broken."

This might be due to habitat restoration (like with lake sturgeon), strict size and kill limits (muskies), and changed ecosystems (like how zebra mussels and warmer temperatures have damaged a once-fantastic walleye fishery on Mille Lacs Lake, while benefitting muskies and smallmouth bass).

basswoodlakefan: "Do that many people bring fish home from their trip? I just dont know how cutting daily limits would impact it that much? I could keep 6 walleyes a day but I cant eat 6 walleyes a day. "

True. But three anglers taking two fish each has the same impact as one angler taking his 6 fish limit. The fact remains that a LOT of anglers fish the BWCAW when compared to how infertile the lakes are. And most foks probably are far more effective than they were a generation ago, as electronics make those mid-lake reefs and suspended fish visible.

The introduction and spread of smallmouth bass have definitely impacted the food chain on many lakes, impacting both walleyes an lake trout the most. Walleyes introduced into lake trout waters in the eastern BWCAW where they were not native likely degraded or eliminated lakers from some lakes.

I'd like to see a year-round, no limit fishing season for smallmouth bass in the BWCAW and a mandatory catch and kill for them on those lakes where lake trout and smallmouth are the only gamefish. The mandatory kill rule is often applied to invasive brook trout on cutthroat trout waters out west, so it's not a draconian thing.

arctic: "

basswoodlakefan: "Do that many people bring fish home from their trip? I just dont know how cutting daily limits would impact it that much? I could keep 6 walleyes a day but I cant eat 6 walleyes a day. "

True. But three anglers taking two fish each has the same impact as one angler taking his 6 fish limit.

So, if we cut the limit to two walleyes per person, does that change anything with 3 guys taking 6 vs 1 guy taking 2? Lol. I am not sure what's a reasonable number of fish for someone to have for a shore lunch. Or size for that matter. I can't remember the year but essentially, the DNR said dropping the limit to 4 would have no impact on the fisheries as a whole, if they (anglers) wanted real change it would have to go to 2 and nobody wanted that.

Also, it was brought up again at the roundtable a few months ago about going to a statewide 4 fish daily limit, with 8 in possession. Don't be surprised to see this on the floor in 2025-2026. Recent survey is basically split 30/30/30 for those in favor, those in not and those who don't care.

arctic: "

Speckled:


One other thought - nearly all state record fish continue to be broken. Larger and larger fish continue to be caught. There's a few older records out there, but mostly they're being broken."

This might be due to habitat restoration (like with lake sturgeon), strict size and kill limits (muskies), and changed ecosystems (like how zebra mussels and warmer temperatures have damaged a once-fantastic walleye fishery on Mille Lacs Lake, while benefitting muskies and smallmouth bass).


"

When was the last time you fished Mille Lacs?

Global warming is affecting lakes and like cisco and burbot in MILLE LACS. But the lake still has a very good-excellent population of walleye. Current regs are present because of biopolitics between the tribes and Mn DNR Fisheries. Most all of the present MN DNR Fisheries retired and still working will tell you the lake could easily have a 4 fish limit. Some have and given different duties or fired or reprimanded. Science takes a back seat on the lake. They do have so much good data on the lake, but not used objected by the tribe.

That said most lakes in Minnesota are overfished.

Yes smallmouth have ruined many stream trout lakes, the State abandoned stocking them. How they got into these lakes?

arctic:

True. But three anglers taking two fish each has the same impact as one angler taking his 6 fish limit. The fact remains that a LOT of anglers fish the BWCAW when compared to how infertile the lakes are. And most foks probably are far more effective than they were a generation ago, as electronics make those mid-lake reefs and suspended fish visible.

"

This to me is huge - maybe not in the BWCA so much, but definitely in our local lakes. The technology has tipped the scales to the point of being unfair and ethically questionable. With side imaging features it is so much easier to find fish these days

People argue, "well you still have to get them to bite" but the constant pressure definitely takes its toll. I have seen videos of people just cruising around looking for the trophy fish. Easy to see how fish populations and sizes can get nailed so easily now.

Wish the DNR would regulate electronics to put the sport back into it.

Pinetree: "Global warming is affecting lakes and like cisco and burbot in MILLE LACS. But the lake still has a very good-excellent population of walleye. Current regs are present because of biopolitics between the tribes and Mn DNR Fisheries. Most all of the present MN DNR Fisheries retired and still working will tell you the lake could easily have a 4 fish limit. Some have and given different duties or fired or reprimanded. Science takes a back seat on the lake. They do have so much good data on the lake, but not used objected by the tribe.


That said most lakes in Minnesota are overfished.


Yes smallmouth have ruined many stream trout lakes, the State abandoned stocking them. How they got into these lakes?"

SPOT ON.

RatherbeDuffing: "


Wish the DNR would regulate electronics to put the sport back into it. "

Where do you draw the line? People have been arguing about electronics since they came out?

cwallace: "

RatherbeDuffing: "



Wish the DNR would regulate electronics to put the sport back into it. "

Where do you draw the line? People have been arguing about electronics since they came out?


"

I don’t know, but I don’t have much hope that there will be regulation with the amount of money on the line for retailers.

Argo: "I wish bass were never introduced to these waters. I much prefer the native species."

Walleyes aren’t native to most of the BWCA either.

GunflintTrailAngler: "

Argo: "I wish bass were never introduced to these waters. I much prefer the native species."

Walleyes aren’t native to most of the BWCA either."

Good point.
I talked with the head of Quetico a few years ago.
He said water temps have really affected lake trout populations on marginal lake trout lakes.

RatherbeDuffing: "

arctic:


True. But three anglers taking two fish each has the same impact as one angler taking his 6 fish limit. The fact remains that a LOT of anglers fish the BWCAW when compared to how infertile the lakes are. And most foks probably are far more effective than they were a generation ago, as electronics make those mid-lake reefs and suspended fish visible.


"

This to me is huge - maybe not in the BWCA so much, but definitely in our local lakes. The technology has tipped the scales to the point of being unfair and ethically questionable. With side imaging features it is so much easier to find fish these days


People argue, "well you still have to get them to bite" but the constant pressure definitely takes its toll. I have seen videos of people just cruising around looking for the trophy fish. Easy to see how fish populations and sizes can get nailed so easily now.


Wish the DNR would regulate electronics to put the sport back into it. "

They tried once to regulate electronics in the 1970's, there is so much pressure by manufactures and certain groups of fishermen, the DNR never could pull it off. Maybe special regs for electronics in the BWCA would fly. Legislature and Govenor would have to push it thru.

Yes side view radar-locators will destroy fish populations in many lakes. Many who have them don't even fish until they run all over a lake and locate their quarry. They are so sophisticated.

Al Linder IN Fishermen use to say its all about Location-Location-Location when fishing. That is most of the battle in catching fish.

timf1981: "

GunflintTrailAngler: "

Argo: "I wish bass were never introduced to these waters. I much prefer the native species."

Walleyes aren’t native to most of the BWCA either."

Good point.
I talked with the head of Quetico a few years ago.
He said water temps have really affected lake trout populations on marginal lake trout lakes."

Yes many of the smaller shallower lake trout lakes will be hit hardest. Also as lakes warm, fish like smallmouth bass will survive better and compete for forage and eat lake trout.

Any chance plastics could reduce average size of saltwater fish? Guessing it wouldn't be a factor in freshwater and BWCA fish. But there seems to be plenty of plastic in the ocean, meaning saltwater fish would consume at least some plastic regularly, right? Plastic consumption in humans in recent years has been proven to reduce average size in reproductive organs and (if memory serves me correctly) overall growth.

I don't think growth rate has slowed in fish in the BWCA,except in cases where maybe smallmouth are consuming food that maybe walleye or lake trout ate.
Biggest problem is overfishing.
I have an old report of Creel census on Mountain and West Pike Lake dating back into the 1950's. West Pike Lake trout fishing was awesome. BUT THE DECLINE BEGAN, resorts back then motored across Clearwater Lake and stored boats od West Pike, the amount of lake trout taken was unbelievable in an untapped resource at that time. A 20-inch lake trout is 10-20 years old. Very slow growing. Well, West Pike size and number is smaller now.
Clearwater Lake in the 1950's-60's I had a photo of an individual in one day in the winter who caught and kept 3 trout 16- 20 ponds. These real big fish are like 30 years old, you can't replace them.

I will say tho Knife Lake, the lake trout fishing is better now than in was 55 years ago. Why?
The winter fishing by snowmobile in the 1960-70 era with 100's of people decimated the lake trout population there. Since snowmobiles were banned, the fishery has improved greatly.
The potential is still there if managed right and fisher people do their job on how and what they keep. Yes, eat a few more northern pike or smallmouth instead of trout.

Your whole post is spot on, Pinetree.

My friend and college roommate is from the Range, and his step-dad, and many others, would snowmobile into Knife in the morning, catch a limit of trout, ride home, and return in the afternoon for another limit. It was like saying f**k you to the DNR and forest service. Weekends saw a LOT of anglers on the lake, and the pressure really damaged the resource. But after snowmobiles were banned the fishery really recovered over the next 10-20 years, so Knife is back to being a productive trout lake.

There is a Smallmouth Bass Explosion taking place here in North Western Ontario in WMU#6 while there is a Black Crappie Explosion taking place in WMU,s #4 & 5 with a smaller Largemouth Bass Explosion taking place in WMU# 4 & 5. Although clearly stated in The Ontario Fishing Regs on page 14 under General Prohibitions that it is a illegal. It is the only way this sharp rise in these species populations could be happening as fish can't get to most areas where this is occurring . Introductions are probably the result of Cottage owners or Outfitters who have the most to gain and not the general population week end warrior...

Caministigoyan: "There is a Smallmouth Bass Explosion taking place here in North Western Ontario in WMU#6 while there is a Black Crappie Explosion taking place in WMU,s #4 & 5 with a smaller Largemouth Bass Explosion taking place in WMU# 4 & 5. Although clearly stated in The Ontario Fishing Regs on page 14 under General Prohibitions that it is a illegal. It is the only way this sharp rise in these species populations could be happening as fish can't get to most areas where this is occurring . Introductions are probably the result of Cottage owners or Outfitters who have the most to gain and not the general population week end warrior... "

For sure. There has been a lot of "bucket biology" going on over the years. The smallmouth bass invasion in the Quetico-Superior was started by resorts in the 1930s to offer late summer angling opportunities when walleyes tend to be harder to catch. And walleyes introduced into lake trout waters has actually eliminated trout from a number of lakes over the years.

Vincent "Vince" Armstrong " The Fuel/Lube Truck Driver" May 2, 1958 - Oct 22, 2017 of Atikokan , Ontario used to be our Fish Fry Guy on Mouse Time 'On the weekends' when the cats were away at the Bucket Welding shop @ LDI Mine he did a lot of Walleye fish fries but he would not share his Black Crappie he said they were too good for us or so he said.. Vince used to fish down Flanders Road towards Lac La Croix FN for Black Crappie, Large Mouth Bass and Blue Gill. Vince was also a member of the Atikokan Walleye Hatchery which has helped out that area considerably. I googled Grand Portage Native Fish Hatchery which raises Coaster Brook Trout and Walleye perhaps they may be of help in the stocking of Walleye and Black Crappie in the BWCA in Cook County Minnesota.

Last two years up in Ontario we had epic fish. They were one after another. We had a hard time getting fish that were in the slot limit. They were simply too big. This is on a huge lake about 100 miles north of the BWCA.

Don’t complain if you don’t eat smallmouth.Its looked down upon to kill smallmouth because of the huge catch and release mantra among bass anglers while walleye are just looked at as meals.Smallmouth are better then walleye when caught out of clean water like the B-Dub.I make a point to eat a smallmouth out of clean wilderness lakes while canoeing because they are DELICIOUS!!!!!! The meat is beautiful and more flavorful then walleye.

Sturgeon Lake?... It's about 65 miles long and about 100 miles north of the BWCA. Fishincanada Episode 555 covered Lumber Jack Lodge and the Walleye rehabilitation project taken on by the Ignace MNR @ Bell Creek with the help of The Atikokan Walleye Hatchery. Lots of the older crew members & equipment at LDI Mine came from Mattabi Mine and the other old mines on Sturgeon Lake north of Ignace, Ontario.

I have fished the area around Sturgeon Lake and it was the best fishing I have experienced in my lifetime. There was no shortage of large fish in those lakes. Lost count of the 20-25" walleye we caught. None over 30 but a few 28s & 29s.

I don't think I fish the BW enough to say that I have noticed a big difference in the size of fish over the last 20+ years but I don't doubt there are less now than when I started. I also spend a lot of time fishing put and take lakes and last year was the best quality fishing I have experienced in those lakes.

I do believe something needs to change with the limits. There is more fishing pressure than ever before and people are more skilled and knowledgeable not to mention the technology changes over the years.

In 1966 my family used to fish @ Hume Station just above the Kakabeka Falls the limit on Walleye was 6 per day and there was no fishing licence in Ontario until 1976. The amount of fishing pressure and the increase in the technology of the fishing equipment has changed that reality now I would have to travel to the Little Jackfish River past Armstrong Station, Ontario which has a 2 fish daily limit to see that kind of Walleye action which doesn't get me too interested with the price of gas. I make do closer to town but the fishing gets better every 50 miles from Thunder Bay as there is a large population of Walleye Angler's here probably over 90% of the Anglers here fish primarily Walleye. Some of the Resorts around here have used the Atikokan Walleye Hatchery to boost their Walleye populations as their client's want Walleye and a Resort on a lake with few Walleye doesn't attract many visitors and affects their bottom line $$$...

I'm not an expert, but have studied fish biology. There are probably multiple reasons for smaller fish, but there is zero doubt that they are smaller than they used to be in many BW lakes. I don't doubt that rising temps could be a factor for some species, especially Lakers and some forage species, but I doubt a 2 degree temp increase in 50 years is the entire reason. I believe it is mostly fishing pressure, as it seems the evidence points to that. Take Knife lake for example, it is a shell of it's former self for Lakers, but I know of several hard to get to Quetico lakes that have Lakers to at least 20# with many over 10# and are crawling with Smallmouth, Pike and Walleye. Knife, seeing high fishing pressure, seems to continue its decline. Even though there is a lot of catch and release fishing, a fair number of these fish still do not survive, especially Lakers. If Lakers are kept out of the water for more than a minute, laid down on the floor of the canoe, or caught when temp is high, mortality has been shown to be high whether they swim off or not. Large pike have a high mortality rate as most people are not equipped to deal with them and they are a very fragile fish. The reason all this matters is that these larger predators are extremely important for several reasons. Both pike and Lakers are very cannibalistic so large ones are what keep their own population under control. Too many smaller top predator species mean that these fish stunt as they are all competing for the same size food as walleye and small mouth and everyone gets stuck in a low growth cycle. It is ultra critical to protect the largest fish to avoid this. There are many other factors at play, but the evidence is undeniable that in these shield lakes, the ones with the most fishing pressure are seeing the greatest change in fish quality and health. I have seen a noticeable change in the 20 years I have been tripping up there. I'm not sure what the answer is, but please treat large fish of ALL species with care, and NEVER assume that killing a large pike is not doing serious damage to the walleye or laker fishery because that would be unlikely from every study done on the subject. If you drag a large pike to shore or let it thrash on the floor it is unlikely to survive. You get large fish when there is enough of the desired prey size for them to grow, and this is difficult when there are too many fish of the same size feeding on the exact same thing, especially in these very low fertility waters.

mgraber,

I fully agree with your views on fishing pressure and the mortality of poorly handled, released fish. I would argue though that Knife Lake was probably at a low point in the 1980s after years of heavy winter lake trout angling via snowmobile. I heard stories from my college roommate's dad (an Iron Ranger) about folks riding up to Knife in the morning to catch a limit of trout, taking them back to town , and then returning for another limit in the afternoon.

I mushed into Knife to fish and winter camp with a buddy for many years up until a few years ago, and we generally had very good trout fishing.

I've long thought the BWCAW should have a separate set of angling regulations---more in line with NW Ontario---due to the low fertility of Canadian Shield lakes and relatively high fishing pressure on many lakes.
Maybe a two walleye limit, one lake trout, and a 22-36 inch protected slot on pike. Some pike lakes have a high potential for producing trophies, and should me managed for such. Keep smallmouth bass at 6 and enact a mandatory catch and kill policy for smallmouth on certain, infertile trout lakes with a simple, invertebrate-based food web (some western states require catch and kill for certain aggressive species on select trout waters).

I'd probably close the lake trout season from mid-July to the end of August to protect them from the high mortality on trout jigged up and hauled through and released into warm surface waters.

Arctic, I stand partially corrected on knife lake, that is some interesting information. I still believe that Knife has seen a decline from fishing pressure but am glad it is still producing decent fish. There are many other examples, not that you are arguing that fact. I would vote for your more restrictive limits, except I would like to see no kill of large pike(like over 30# or so). I doubt killing smallmouth on any lake would help much, but it couldn't hurt on the ones where they do the most damage. I do love smallmouth but they do not belong everywhere. I wouldn't mind seeing a no kill of large walleye either( 24" maybe)? There are some of the larger more fertile lakes in Quetico where it appears that the smallmouth are doing no harm and possibly even helping, but these are fertile(for shield lakes) and extremely varied in habitat so the different species are not so forced in to the same environment. We are probably making enemies by talking about restrictions. lol

Very true about making enemies. I do like the idea of a no-kill reg for large pike and walleyes. Lake trout too. BWCAW fishing really should be on par with Quetico, but as you pointed out, it's the fishing pressure that makes them different.

Nearly every problem in the BWCAW---be it crowding, campsite avaiability, fisheries decline---are the result of poor managment decisions based on politics.

Maybe have some trophy LT lakes.
Catch and release only and/or no fishing July1-sept 1.

I'd bet the amount of fishing pressure per acre on the easily accessed BWCA lakes exceeds most lakes in the state and rivals the "big names" like Leech, Winnie, Mille Lacs, etc. It's a lot harder to catch fish from a canoe than in a big boat, especially on big water, but day in and day out, lakes like Agnes, Brule, Disappointment, etc. see a TON of pressure.

And a lot of the fish go into the fry pan; some groups I know eat fish every chance they can.

Speaking of Knife Lake, have you guys seen the photos from the old days (like w/ Dorothy Molter) of HUGE trout and pike? I get that they didn't take pictures of every fish, so the sample skews towards large fish, but man, there used to be some tankers in there. I know there are some still in there, but when's the last time you saw a photo of a giant lake trout taken out of Knife? The "big" ones these days would be bait for the ones from a generation or three ago. Just my .02.

carmike: "I'd bet the amount of fishing pressure per acre on the easily accessed BWCA lakes exceeds most lakes in the state and rivals the "big names" like Leech, Winnie, Mille Lacs, etc. It's a lot harder to catch fish from a canoe than in a big boat, especially on big water, but day in and day out, lakes like Agnes, Brule, Disappointment, etc. see a TON of pressure.


And a lot of the fish go into the fry pan; some groups I know eat fish every chance they can.


Speaking of Knife Lake, have you guys seen the photos from the old days (like w/ Dorothy Molter) of HUGE trout and pike? I get that they didn't take pictures of every fish, so the sample skews towards large fish, but man, there used to be some tankers in there. I know there are some still in there, but when's the last time you saw a photo of a giant lake trout taken out of Knife? The "big" ones these days would be bait for the ones from a generation or three ago. Just my .02. "

I disagree. In the winter the 350 acre lake I live by has probably close to 50 permanent houses on it and I know a few retired guys that fish it almost every single day in the winter. This just isn't happening on lakes entirely in the BWCA. Some of the close entry trout lakes do get hit hard but walleye receive almost zero pressure in the winter.
I'm not going to be convinced that a lake like Agnes is receiving more pressure year round than the lake by my house unless there is some data to show it. In fact if you base it on acreage I don't think it's even close.