Claim: Lake Erie yellow perch threatened by 'climate change', but predation may be the bigger cause

Before you read this story blaming the universal bogeyman ‘climate change’ for the decline in yellow perch, it might be a good idea to listen to what the fishermen and other researchers have to say:

Scientists studying the lake and fishery say there are numerous reasons why. They include changing water quality and clarity and the effects of recent warming trends. Yellow perch are a cool-water species.

Recent study findings, however, also suggest that Lake Erie’s booming white perch population has had more of an impact than previously thought. They prey voraciously on tiny yellow perch.

“The numbers are staggering,” said Stuart Ludsin, an associate professor of evolution, ecology and organismal biology at Ohio State University. Ludsin has been studying the lake and its fishery for 20 years.

“There are between 46 million and 106 million predators in the western basin of Lake Erie. In just 24 hours they can consume between 32 million and 189 million yellow perch larvae. That is an enormous number.

“We don’t have that broken down by how much each eats, but I can tell you that white perch make up 90 percent of the predators. It is the most abundant predator in the lake. Period.”

Walleyes and white bass also prey on larval yellow perch. Even adult yellow perch will “cannibalize” their own young, according to Ludsin, but nothing approaches the volume that white perch eat. His evidence was found in white perch stomachs.

Full story in Michigan Outdoor News: Increasing white perch affecting Erie’s yellows

Also, this EPA report on Yellow Perch in Lake Erie doesn’t mention climate change or global warming at all. They do have this graph, which has an interesting peak in 1979, one of the coldest winters for Lake Erie ever, so it appears that there is some sensitivity to temperature, but it seems more weather than climate related. I agree that temperature is a factor, but this looks to be more of a case of weather, not climate.

yellow-perch[1]And according to the Michigan Outdoor News article, the predators got a kick-start in the 1980’s:

“In the 1980s we had a series of four very warm winters. That allowed the small adult population of white perch to survive and get off several very strong year-classes. The white perch population then exploded,” Ludsin said.

And the EPA article from 2009 says:

There also may be an inverse relationship between the peak walleye abundance periods (late 1980s-early 1990s, and more recently since 2003) with yellow perch abundance. When walleye abundance is very high, it appears that yellow perch abundance declines and probably is due to predation (Thomas 2006).

So it seems predation is the dominate factor, followed by weather, and I’m betting the “climate change” angle was thrown in to grab headlines. Some scientists, like fishermen, know what bait to use to reel in the big ones.

From Ohio State University: Climate change threatens one of Lake Erie’s most popular fish

Short, warm winters spell trouble for young yellow perch


COLUMBUS, Ohio – Research has suggested yellow perch grow more rapidly during the short winters resulting from climate change, but a new study shows warmer water temperatures can lead to the production of less hardy eggs and larvae that have trouble surviving these early stages of life in Lake Erie.

The research also showed that yellow perch don’t adjust spawning to match earlier spring-like temperatures. This poses a problem if the hatchlings’ main food source, zooplankton, does make a temperature-based adjustment because supplies may be low by the time larvae are ready to feed.

“If not enough food is available, the larvae will grow slowly and be vulnerable to predators like invasive white perch,” said Stuart Ludsin, principal investigator of the study and an associate professor of evolution, ecology and organismal biology at The Ohio State University.

On average, eggs produced in long, cold winter conditions in a lab experiment were 30 to 40 percent larger and their hatching success was between two- and four-fold better than the smaller eggs produced under warm, short winter conditions.

The survival problem could help explain why yellow perch numbers in Lake Erie have been low since 2003, and stand at only about half of the average fish population recorded during its heyday in the 1960s and ’70s.

“There are a lot of factors that can help explain why yellow perch numbers are low in Lake Erie. The warmer winter temperature clearly is an important one,” said Ludsin, also co-director of Ohio State’s Aquatic Ecology Laboratory. “For management agencies, there is no easy fix to this problem.”`

The study is published in the journal Nature Communications.

Ludsin first saw a relationship between warmer winters and reductions in the annual abundance of juvenile yellow perch in Lake Erie while working on his dissertation at Ohio State more than 15 years ago. He has spent much of his career working with Lake Erie fishery managers to try to explain why yellow perch numbers have fluctuated so dramatically over the past four decades.

For this study, the researchers combined long-term fisheries assessment data, a lab experiment and fieldwork to gauge the effects of warmer winters on one of Lake Erie’s most popular fish among commercial and recreational anglers.

Yellow perch live on the bottom of Lake Erie, where water temperatures are about 40 degrees Fahrenheit (4 degrees Celsius) during the winter, said lead author Troy Farmer, a postdoctoral fellow at Auburn University who completed this work as a graduate student at Ohio State.

The scientists collected wild yellow perch from the lake with the help of state and federal biologists. In the lab, the scientists exposed different groups of fish to historic cold winter conditions or to warmer temperatures that have been recorded in more recent years.

Farmer said a long winter in the lab featured 107 days of water temperatures below 42 degrees Fahrenheit (5 degrees Celsius), which represented the average winter duration over the past 25 years. Under short winter conditions in the lab, the temperature remained under 42 degrees Fahrenheit for only 52 days, mimicking the length of the winter recorded in 1999.

“Our temperature treatments represented environmentally relevant conditions that are already being experienced by fish populations in Lake Erie,” Farmer said.

Females exposed to warm, short winter conditions produced just as many eggs as their counterparts experiencing a long winter, but egg quality differed: They were smaller and didn’t hatch as well, and eggs that did hatch produced unusually small larvae.

Yellow perch also don’t show signs of adapting to warmer temperatures by fully adjusting when they spawn, Ludsin said. In both the lab and the field, the researchers observed that females continued to spawn in the historically typical months of April and May even when air temperatures reached the 80s in March in 2012.

“In lots of cold-blooded species, we find that as spring occurs earlier, the timing of reproduction will also move forward,” Ludsin said. “Walleye are a great example. In the record short winter of 2012, walleye moved their spawning period up by several weeks. With yellow perch, we didn’t see that.”

The supply of zooplankton that yellow perch larvae eat can peak early along with warm weather. If food is scarce at the time eggs hatch, larvae will grow slowly and remain vulnerable to invasive white perch, a key predator in Lake Erie.

“If we didn’t have that predator in the lake, the larvae that actually hatch after a warm winter might be able to survive just fine. But having short winters lead to low-quality larvae is a big disadvantage because of the risk of getting eaten,” Ludsin said.

The research doesn’t explain the biological mechanisms behind these reproduction problems for yellow perch.

“Yellow perch might have an inability to adjust their spawning to take advantage of those warm temperatures when they occur,” he said. “Is there something hard-wired in them, like some physiological limitation, or an effect of temperature on hormones? We just don’t know.

“It could be that we’ll have to wait for adaptation to occur because there is no obvious quick fix. And, other ongoing stressors like nutrient pollution that causes low-oxygen zones and harmful algal blooms in Lake Erie don’t help the situation,” Ludsin said.

Ludsin also is principal investigator on a state-funded study looking at potential human health concerns associated with eating yellow perch and walleye caught from areas of Lake Erie affected by harmful algal blooms.


The yellow perch study was funded by the Federal Aid in Sport Fish Restoration Program, administered jointly by the U.S. Fish and Wildlife Service and the Ohio Division of Wildlife, the Great Lakes Fishery Commission’s Fishery Research Program, a Norman S. Baldwin Scholarship from the International Association for Great Lakes Research and a Presidential Fellowship from Ohio State.

The Ohio State research team also included co-authors Elizabeth Marschall, chair of evolution, ecology and organismal biology and co-adviser with Ludsin on Farmer’s graduate work, and Konrad Dabrowski of the School of Environment and Natural Resources.

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July 15, 2015 2:18 pm

Everything bad is because of climate change. It makes finding the cause of undesired changes easy.
The true climate deniers are those who believe the climate is now how it always has been, always should be, and any change from that must be bad and must be caused by people. If people weren’t here, there’d be no climate change, and yellow perch would be happy, and the lamb would lie down with the lion, and…

Reply to  Richard
July 15, 2015 3:28 pm

Richard: “The true climate deniers are those who believe the climate is now how it always has been”
And claim it will remain so as long as they can keep putting up taxes and restricting personal freedom…

July 15, 2015 2:25 pm

Since Lake Erie was declared a dead Lake several decades ago, and yet there are still fish living it today numbering in the millions, what is all the fuss about?

M Courtney
July 15, 2015 2:33 pm

Prey/Predator relationships are complex and show chaotic behaviour: Ecology101.
So it’s easier to assume a linear response to temperature as the dominant factor.
Easier, simpler and, of course, wrong..

Reply to  M Courtney
July 16, 2015 3:50 am

Agreed. This research seems to have been well planned and orchestrated. No wrong conclusion jumping. Science in action.

Craig Moore
July 15, 2015 2:34 pm

Walleye love to eat yellow perch like a T-Rex going after a tied down goat on that island somewhere. Erie has some monster walleye.

Alan Robertson
Reply to  Craig Moore
July 15, 2015 3:32 pm

It took a lot of Yellow Perch to make those big Walleye cheeks.

Craig Moore
Reply to  Alan Robertson
July 15, 2015 4:40 pm
Neil Jordan
Reply to  Craig Moore
July 15, 2015 3:40 pm

You might be referring to the “Tethered Goat” cartoon by Josh, in a WUWT post at least a year ago. The goat had a resemblance to a certain hockey stick purveyor. There was a Truthosaurus Rex in the background.

Craig Moore
Reply to  Neil Jordan
July 15, 2015 4:45 pm

When the T-Rex approached that goat screamed like Al Gore at a coal convention.

July 15, 2015 2:40 pm

“The research doesn’t explain the biological mechanisms behind these reproduction problems for yellow perch.”
Actually the research doesn’t explain anything, it adds a little more data that, if interpreted correctly, may or may not aid in a better understanding of the general nature of stuff.

Reply to  DonM
July 15, 2015 2:42 pm

Actually the research doesn’t explain anything AT ALL, …

July 15, 2015 2:41 pm

Short, warm winters on lake Erie? Not lately!

Reply to  Dawtgtomis
July 15, 2015 2:50 pm

As I can recall the last two winters I was able to ride a snowmobile from port Clinton to put in bay. As for perch I haven’t had any problems catching them only fish not biting are catfish. Plain and simple lake Erie isn’t dead it’s thriving. As is superior,Michigan,Huron. This climate change scam needs to stop!

Reply to  Dawtgtomis
July 15, 2015 2:54 pm

Ice, ice, baby!

Reply to  Dawtgtomis
July 17, 2015 11:52 pm

I don’t know about your fresh water fish, but rainbow trout only spawn in winter months, and we can’t fish then in waters that contain trout. But I would think if Lake Erie is iced up, not enough CO2 is being released from the water. Lots of reasons why fish numbers decline. But if others are surviving, then ????? If it was pollution etc., all fish species and fish food would be affected. Maybe the salinity has altered?

Gunga Din
July 15, 2015 2:48 pm

Maybe I missed it but I didn’t see any mention of zebra mussels.

Craig Moore
Reply to  Gunga Din
July 15, 2015 2:55 pm

The zebra mussels were savagely attacked by the Freshwater Lionfish.

Tom J
Reply to  Craig Moore
July 15, 2015 3:20 pm

Actually, I think it was the piranhas.

Craig Moore
Reply to  Craig Moore
July 15, 2015 3:40 pm

Tom, Pacu have been caught in Erie. Pacu are know as the “ball cutter.” Hopefully, there are enough perch around to keep them occupied.

Gunga Din
Reply to  Gunga Din
July 15, 2015 3:30 pm

Here’s a bit more about them and Lake Eire.
My point (whether a valid point or not) is that the invasive zebra (and quagga) mussel has effected the clarity of the water in Lake Eire. The temperature of the water isn’t the only factor and I didn’t see them mentioned.
PS I went fishing on Lake Eire back in the mid to late 80’s. We caught quite a few white perch. We thought at the time they were white bass.

Brian Jones
Reply to  Gunga Din
July 15, 2015 5:36 pm

Zebra mussels have cleared the plankton out of the St Lawrence essentially devastating the perch fishing.

July 15, 2015 2:50 pm

This is just more Heifer Dust. People today blame CO2 and “global warming” the way people used to blame “witches” for everything under the sun they did not like. Bad marriage? It was a witch down the road! These days, if your wife does not want to do the nasty —->>> Global Warming! Fish die off? —->>> Global Warming! IRS problems? —->>> Global Warming!

Reply to  markstoval
July 15, 2015 3:10 pm

I dispute your assertion that global warming is responsible for the loss of a wife’s sex drive. There are many, many anecdotal reports implicating wedding cake as the primary culprit.

Tom J
Reply to  SMC
July 15, 2015 3:22 pm

That’s worthy of a Doctoral dissertation.

Reply to  SMC
July 15, 2015 3:31 pm

Don’t get married in Vegas while drunk. Simple.
Oh, it is the hot desert that does this, too! 🙂

Reply to  SMC
July 15, 2015 5:28 pm

Please provide funding and I will develope a model to prove the effect of wedding cake on the female libido.

Just an engineer
Reply to  SMC
July 16, 2015 5:52 am

Here is one along those lines,
I didn’t say “Married women are smarter!”. I said, “Married women no more!”

Gunga Din
Reply to  markstoval
July 15, 2015 3:35 pm

Fish die off? —->>> Global Warming!

The number of skeptics increase?—->>> Global Warming!

July 15, 2015 3:04 pm

From a certain cockeyed perch, everything looks “threatened” by climate change.

July 15, 2015 3:16 pm

The past few Ohio winters have been brutally cold-I live in NE Ohio,and do commercial snow removal in winter,both parking lots,and get out of the truck and shovel sidewalks,stairs,loading docks,etc. it’s been extremely cold,for months the past few winters-in about 5 years,yellow perch populations will be booming again.
These people are smoking crack,and/or taking LSD,peyote,psilocybin mushrooms-or they’re just brain-dead.
The two biggest problems for yellow perch populations are zebra mussels,and invasive white perch.
People need to start killing every white perch they catch-or cat food companies need to start buying them from fishermen.
Get rid of the white perch-yellow perch rebound.
Yellow perch populations have fluctuated wildly since the lake was cleaned up enough for fish to return to all of it.
Then the zebra mussels came,water got really clear-and fish populations began to suffer,as zebra mussels eat the same thing yellow perch and walleye eat-zooplankton.
Has nothing whatsoever to do with “climate change”.

Reply to  gamegetterII
July 16, 2015 9:20 am

Good summation, GamegetterII! +1
I’ll follow up with some quotes below.

Reply to  gamegetterII
July 16, 2015 9:26 am

I’m glad to see there are a lot of people from NE Ohio here!

Paul Coppin
July 15, 2015 3:16 pm

Erie is a complex eutrophicating lake. Ascribing anything to “climate change”, even if you could, would be daunting task. Shallow, highly susceptible to runoff, clarity issues, algal blooms, pollution, Predation may well be a dynamic factor, but there are many others. Climate change isn’t one of them.

Reply to  Paul Coppin
July 16, 2015 5:19 pm

The only clarity issue is the water is far too clear due to zebra mussel infestation.
The zebra mussels are in all the NE Ohio inland reservoirs as well.
Agreed climate change has nothing to do with swings in yellow perch populations.

July 15, 2015 3:19 pm

They do keep carping about the same old thing, don’t they??

Tom J
Reply to  ShrNfr
July 15, 2015 3:24 pm

Are carp disappearing in Lake Erie too?

Gunga Din
Reply to  Tom J
July 15, 2015 4:22 pm

Carp are also an invasive species but they’ve been around so long we forget. Same for smallmouth bass west of the…I forget. (Back in the days of wood-burning steam engines fingerlings were carried west and stocked out of water buckets.)
Those who want to return America back to it’s “natural” state (When they say that, they usually only mean before Columbus.) are going to have their hands full killing off all the critters whose range is “different” now than it was then.

July 15, 2015 3:26 pm

Sort like the contemplated listing of the Sage Grouse as endangered. There is a whole new ecology in place of the one in which the Grouse was the representative species. It includes now Pheasant, Chukkar, and Hungarian Partridge as new denizens of the same niche filled historically by the grouse.

Reply to  fossilsage
July 16, 2015 5:22 pm

You forgot the most important reason for sage grouse decline-introduction of wild turkeys.

July 15, 2015 3:27 pm

Perch, walleye, yum!

Reply to  katherine009
July 15, 2015 3:48 pm

(sound of beer can opening with frying in background)

July 15, 2015 3:29 pm

The bumblebees, butterflies and polar bears are killing the fishies.

Reply to  emsnews
July 15, 2015 5:26 pm

You forgot the “Oh My!” There should be an “Oh My!” In there somewhere.

Reply to  SMC
July 15, 2015 9:00 pm

A sob is mandatory also.

James Allison
July 15, 2015 3:39 pm

Perching on the edge of extinction -self groan, quickly switches off computer..

James Bull
Reply to  James Allison
July 15, 2015 11:39 pm

Thank you for my morning laugh just what I needed to get the day going.
James Bull

July 15, 2015 3:41 pm

The biggest threat to man these days, is government-induced climaphobia. It makes the entire world seem like it’s burning up! LOL!!!

Steve from Rockwood
July 15, 2015 3:42 pm

Fried perch, celery bread and a couple of draught beers at the Erie Beach Hotel, Port Dover. Haven’t been there since the 1980s but they were complaining about low fish stocks then too.

July 15, 2015 4:05 pm

Mmmm, Lake Michigan fishies, whitefish for the tourists, but Lawyer-burbots for me! In the Forties, a half-million pounds of burbot livers were purchased in a year by Rowell Labs. Now Lawyers are reserved for the cognoscenti.

July 15, 2015 4:41 pm

how did they get that the lake is getting warmer?….did their computer or old text book tell them??

Reply to  Latitude
July 16, 2015 9:17 am

They have a model……

Reply to  oeman50
July 16, 2015 9:23 am

Actually there’s a better explanation. The world is getting warmer (refer to NOAA data), the number of yellow perch is going down, Viola! Science says that the warming must be causing it. You don’t have to prove the water is warmer, you just have to beeeelieeeeeve……
Do I have to put a /sarc, here?

John F. Hultquist
July 15, 2015 4:44 pm

From 2013; with photo of caught fish:
“…plumes of sediment from the Maumee River are important …”
– To hide the little yellows from the nasty whites.
After 2 very cold winters someone must be out there counting fishes.

July 15, 2015 7:01 pm

I haven’t read all the comments, so maybe this was already mentioned.
I have to ask: Didn’t we just have a couple of cold winters where Lake Erie was nearly completely ice-covered? Certainly, it seems to me the entire Great Lakes had more than usual ice-cover the past couple of years, so much so that it even turned off the lake-snow machine for a few weeks. If yellow perch require colder water to thrive, the last year or so should have been good ones for them.

Mark from the Midwest
Reply to  mjmsprt40
July 15, 2015 7:24 pm

Yes, very cold, and very high ice cover. Temperatures at the 45th Parallel average 7 degrees below normal for JFM of 2013. We also went from very low water levels in the upper lakes to very high and very cold water in the upper lakes. That cold water is currently headed down the Detroit River and into Lake Erie at a record rate. I’m sure that by this time next year the fish story will be completely different, but it will also be blamed on global warming

Reply to  Mark from the Midwest
July 15, 2015 8:38 pm

I saw -20F 20 miles south of the lake , and friends saw -23F 50 miles south of the lake over winter.
My Dad drove over the ice from Sandusky to the Islands in the late 50’s.

Reply to  Mark from the Midwest
July 15, 2015 8:41 pm

And it’s in the 50’s out tonight, 15 – 20F below normal.

Reply to  Mark from the Midwest
July 16, 2015 5:55 am

“And it’s in the 50’s out tonight, 15 – 20F below normal.”
Ha, that’s called weather. Now if it was above normal, that’s climate change!

Reply to  Paul
July 16, 2015 7:03 am

Ha, that’s called weather. Now if it was above normal, that’s climate change!

It’s the universal climate change caused cooling, the warm west coast pushed the Jet Stream north out west, which pushes it south over the great lakes, which gives us a summer of Canadian cool air.
It’s also why the temp series show more warming, the midwests temps are abnormal, and are adjusted with west coast temps. 🙂
But, these are the temps I remember in the 60’s.

July 15, 2015 8:35 pm

Perch go back about 38,000,000,000 years when earth was in a hot house stage. Females can lay up to 40,000 eggs that are poisonous to other fish. Perch ain’t going anywhere. Just like all other species they cycle up and down in conjunction with the predator species.

Reply to  Pathway
July 15, 2015 9:22 pm

Wow, I didn’t realize perch were here before the Big Bang. That’s some impressive fish.

July 15, 2015 10:59 pm

Who can you believe – a guy with a full frying pan or a guy with a computer model?

Grey Lensman
July 15, 2015 11:03 pm

The water was dirty. Now they complain that it is clear and fish thrive. Do these “people” really have no basic comprehension?

July 16, 2015 3:16 am

Many predators, including man…
Mike Durkalec is an aquatic biologist with Cleveland Metro Parks. He ticks off other issues worrying him and fellow fishermen along the Rocky River.
“Some of those would include runoff of phosphorous in particular from agricultural areas, it has caused harmful algae blooms,” says Durkalec. “Non-native species is another one. One big one that affects this particular fishery is the sea lamprey, a non-native species of parasitic fish that does have an effect on the sport fish that these anglers are pursuing.”
Trout Unlimited says annually, an estimated 450,000 people fish the Ohio waters of Lake Erie.

July 16, 2015 8:15 am

White perch came up through the canals. They used to be known as white bass when I was a kid. In Lake Champlain they appeared about 20 yrs ago. Now lake trout, which spawn heavily in this lake, never get past the fry stage. Yellow perch are still very strong in this lake, but we don’t gill net them here the way they do, or did when I lived there, on Lake Erie.
I have fishfinder images of schools of them that look like a whale. One time I stopped the boat after seeing a school about 40 ft down that was 15 feet thick and we fished for them with a three fly rig and brought up over a hundred of them three at a time til we got bored. We drifted about a half mile at a time and never got off the school. Fortunately you can eat them, but they don’t taste as good as yellow perch. And yellow perch are *not* a cool water fish, they are considered garbage fish in warmer waters because of parasites, but they can grown there fine.

Reply to  TJA
July 16, 2015 9:29 am

The only lakes where yellow perch are considered ‘undesirable’ are lakes where they’re overpopulated and severely stunted. Any lake where you can catch decent sized yellow perch they’re considered highly delectable and very desired.
I’ve lived up and down the East coast and am currently living in a ‘warm water’ state.
White perch are also very delectable, very much similar to their cousins the white bass and striped bass. White bass and white perch are two different species that can interbreed with fertile hybrids; unlike most white bass x striped bass crosses which are sterile.
Both white and yellow perch make for excellent fried fish dinners.

Reply to  TJA
July 16, 2015 5:30 pm

White perch and white bass are two totally different fish.

July 16, 2015 8:37 am

Perched on the brink.

July 16, 2015 11:07 am

Following up on GamegetterII’s and dp’s comments above:
Yellow perch are a schooling fish during much of the year and targeting the larger adults means finding the school those fish are in, often out in deep open water; making it tough fishing for the shore bound angler.
Fisherpeople learned long ago that yellow perch gathering for spawning was one of the best times for shore bound anglers and requires fishing during spring thaw near or under the edge of the ice and in the same area till shortly after ice-out. Ice edge fishing is one of the first indications that yellow perch spawn during certain temperature conditions, an early spring vs late spring doesn’t matter to the fish.
From the ‘Outdoor News research announcement’;

“…Walleyes and white bass also prey on larval yellow perch. Even adult yellow perch will “cannibalize” their own young, according to Ludsin, but nothing approaches the volume that white perch eat. His evidence was found in white perch stomachs.
Ohio fisheries officials have said they didn’t consider predation as a factor initially because they found no yellow perch in white perch stomachs. Ludsin said larval yellow perch are tiny and digest quickly. It took doing DNA analysis on the stomach contents to confirm their presence…”

Hallelujah! They found yellow perch dna in the white perch’s stomach! Oddly there wasn’t any sign of yellow perch, so immediately the researchers ruled out all possibilities but the preferred bias.
What if!? The yellow perch dna came from the digestive tracts of white perch consumed small fish that do prey on yellow perch larvae and minnows. Just because the researchers found something does not indicate in any way how that material got there, assumptions only pander to their bias.

“…“In the 1980s we had a series of four very warm winters. That allowed the small adult population of white perch to survive and get off several very strong year-classes. The white perch population then exploded,” Ludsin said.
Recent warming trends, he added, continue to favor the white perch population…”

From “NAS – Nonindigenous Aquatic Species”:

“…Native Range: Atlantic Slope drainages from St. Lawrence-Lake Ontario drainage, Quebec, south to Pee Dee River, South Carolina (Page and Burr 1991). Populations in Lake Ontario drainage probably became established following construction of the Erie Canal…”

From their preferred native range, I seriously doubt that white perch ‘favor’ warm water.
Looks like another false assumption by the researchers.

“…Despite the improvements in water clarity during past decades, the western basin of the lake is again becoming more eutrophic. Steady infusions of manure and chemical fertilizer from farms and other sources like lawn fertilizers and leaking septic systems have created a dead zone in Lake Erie where toxic algae blooms sap the water of oxygen, creating a dead zone where fish die…”

A very odd assumption and statement by the researchers regarding a topic they did not investigate.
What is very odd, several of the online references to Lake Erie reference how much cleaner the water of the lake is. Some attributed the clean water to the influence of EPA, most attributed the cleaner waters to the invasive ‘zebra mussel’.

“…Ludsin’s studies show that young yellow perch survival dramatically increases when wet spring seasons result in high-volume discharges from the Maumee River at Toledo, Ohio. The turbid plume that extends far out into the lake becomes a refuge for yellow perch. There are fewer predators in the plume, and those that are there are eating fewer perch than those outside the plume. Because of the diminished water clarity, yellow perch larvae are harder to find. …”

Well, there is a ‘duh’ finding.
What is very disturbing is the discussion regarding one river, Maumee river in Toledo, Ohio. What about all of the other rivers around Lake Erie? No mention about other rivers leaves us with the disturbing thought that this research was very narrow and very locale restricted; but there appears to be little restriction regarding attribution to all of Lake Erie.

“…“That is the only time we get a strong perch year-class,” Ludsin said. “The young of the year survive and recruit to age two and support the fishery for many years to come.”
The last big yellow perch year-class was produced in 2003, Ludsin said. It still supports the fishery and makes up 75 percent of the catch. A strong year-class, he said, is a game changer…”

From “Great Lakes Perch Boom” article posted April, 2014 (as mentioned by dp, above)

“…Lake Erie: There’s no equal among its Laurentian peers when it comes to producing large numbers of perch. Jumbos in the 13- to 15-inch range are less prevalent here, however. These prolific waters offer 100-perch days with regularity. A Seafood Watch report notes that 85 percent of the Great Lakes’ commercially caught perch come from Lake Erie (8 to 10 million pounds annually), with about 8 percent from Lake Ontario, 6 percent from Lake Huron, and 1 percent from Lake Michigan’s Green Bay.
With strong year-classes in 2005, 2006, and 2008, Erie shows no sign of slowing. Above-average recruitment in recent years is producing large catches of fish averaging 8 to 10 inches…”

In the same article are some notes regarding factors leading to ‘reduced’ yellow perch recruitment affecting yellow perch populations. A major impact to yellow perch larvae;

“…Even in years with good spawns, few young-of-the-year (age-0) perch survive to their second year or beyond to join the catchable population. Lack of food in the form of zooplankton for age-0 perch appears to be a leading cause of poor recruitment. Much of the blame is directed at the exploding populations of zebra and quagga mussels. These water-filterers compete with age-0 perch for zooplankton…”

Another noted impact that curtailing had beneficial results;

“…According to a study published in the Journal of Great Lakes Research, cormorants may have consumed nearly half of the age-0 perch in portions of the lake, along with significant numbers of age-2 and age-3 perch.
A project by the New York State Department of Environmental Conversation and the Ontario Ministry of Natural Resources, to oil cormorant eggs and destroy nests, has lessened cormorant predation on age-0 perch, allowing establishment of a strong 2005 year-class…”

Ludsin finishes his announcement with;

“…Cold winters, like this one, also can help. They result in more viable yellow perch eggs being laid and hatched. Spring rains also make a difference.
“Snow melt we have seen has no predictive effect on perch,” Ludsin said. “The Maumee River is affected more by precipitation. If we have a big rain event this spring, if it is a very wet spring, that could be productive.”

Notice that ‘viable’ adjective? A description that is intended to convey a meaning of ‘less viable’ eggs at other times, yet there was no investigation into egg viability, nor is there supporting ‘lack of egg viability’ true research brought into the article.
Again there is that sole locality point reference indication just how limited the research truly was.
No mention of the various state DNR departments around the Great Lakes that have online information regarding the current health of the yellow perch fishery.
Lots of unproven or unverified assumptions makes this research another less than definitive confirmation bias piece of cr@p.

Gunga Din
Reply to  ATheoK
July 16, 2015 3:36 pm

This is the most current thing I could find quickly for Ohio.
You’d think the limit would be lower based on the paper.

July 16, 2015 12:14 pm

Historic Lake Erie water temperature, °F, max/normal/min for July 16 between 1927-2012: 76/71/64.
Optimum temperature range for Yellow Perch: 66–75°F.
Current Lake Erie temperature: 68°F.
There are factors other than predation that could have an effect, but I don’t think climate change is responsible for agricultural runoff and the failure of Detroit’s sewage treatment system.

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