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Lake Michigan is warming. New report says that could mean trouble for game fish Sep 18, 2018 2:55 pm #21284

  • little bill
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Right on Ben. I am in my seventies and every lake i have fished has changed. Same way with hunting. I can remember when there were no geese and deer in indiana and salmon was something you could only get at the grocery store. Adaptibility is required of any species to survive.

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Lake Michigan is warming. New report says that could mean trouble for game fish Sep 18, 2018 9:17 pm #21287

  • scoffer
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I’m newer to this fishery, but I’ve been fascinated by it since the first time I fished it 5 or 6 years ago aboard a buddy’s boat. Bought my own boat because of it... I take in any information I come across as fast as I can because I want to learn more about it. I love it, and I don’t want to see it go away.

I try to weigh every piece of information I read and see if there is any bias or agenda.

That said, I know what the lake was like 20 years ago going to the beach as a kid / adolescent. Green, stinky, alewife die offs littering the beach... nothing like what it is now.

I think academics, biologists, scientific experts in climate change, and the DNR (who many of the staff fall in to one or more of the preceding titles) should be regarded as the expert in these topics. From my reading so far, they do not have an agenda other than trying to slow or reverse the negative changes that have occurred in the Lake Michigan ecosystem.

Seems to me though that there are some groups out there willing to undermine science, deny or downplay climate change, and twist statistics to accommodate their perspective on how this fishery should be managed.

I’d be interested to see if MSU disputes anything in this dumbed down for the public report, or the raw data.

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Lake Michigan is warming. New report says that could mean trouble for game fish Sep 18, 2018 9:25 pm #21288

  • Dirty
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This is definitely a topic worthy of alot of discussion. Thank you Ben for the additional detail. Here are some thoughts and questions I have:

1) To me, the article seemed like a reason to write a scare piece about "global warming". No "specific " resources were really referenced whatsoever except for a "Purdue Report" which was not linked directly. It was written like an opinion piece, simple as that. I am speaking directly to the media article and not the actual research report.

2) I agree, warming temps are bad for our specific fishery for some target species. This cannot be argued whatsoever.

3) Has there ever been a correlating water warm up in the past that can be compared to now? I have not seen one, but assume there may have been. What were the implications? What happened after? Since the overall yearly climate is erratic, this may be a tough correlation and admittedly may not exist....but it may. What do we know?

4) "water temperatures are projected to increase about 5°F to 6°F above the historical average (Kao et al. 2015) ". What is this projected increase? Are we almost already there? Are we just starting? What is this historical average that is referenced? A few hundred years? 50 years? A cherry picked low point and high point? A median? All my searching I cannot find a chart showing this, but I am guessing it is somewhere just out of my reach.

5) It was noted that heavier ice cover is good for whitefish and perch, but I do believe I have seen data that heavier ice cover is bad for baitfish / alewives which would be detrimental to the salmonid population. Correct me if I am wrong, I am going from recollection which may or may not be accurate. Are we overall half optimistic and half pessimistic here? Are Whitefish on a rebound? Also we have had some of the better perch recruitment's recently correct? These I believe we after some of the colder winters? Is that correct?

6) I think we can all agree, the constant change in LM is inevitable.

7) If you look at the linked chicago mean temp graph www.climatestations.com/wp-content/uploads/2018/02/chiannt.gif that is up and down. If you look at it from 1905 to date, I think you can suggest that the air temp is flat to slightly declining overall. This is the eye test only I will admit. Would have to have the actual data to do a plot. If this is the case, is the lake warming due to clarity and sunlight reaching greater depths due to the mussels primarily? Or do we still think its air temp dependent? What are the thoughts among the DNR etc.?

I bring up these points / questions because I think its deeply worth discussing. I have not the information to agree or disagree but would like to learn more, in detail. I do however take exception to the original newspaper article. And yes it is written for the layman to understand, however articles like that are often written to garner attention to a political agenda as well, hence my skepticism.

I think many have skepticism primarily because not enough information or data is shared. At least not easily publicly accessible and in detail. Its 2018 and nobody trusts a journalist. We do (and should) trust the scientists and real published data.

In god we trust, all others bring data. I have not seen enough data. I am glad you are here Ben - please keep the information coming and keep us extremely well educated and informed. We need more MORE REAL DETAIL. Glad you are hear to assist!

One more note to conclude - please keep in mind that many / most of us have full time jobs and families. Trying to research all of this is often next to impossible. We do not experience it daily and real information is hard to find - so we are definitely counting on some of you experts to inform us and look forward to that.
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Lake Michigan is warming. New report says that could mean trouble for game fish Sep 19, 2018 11:57 am #21290

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Thanks for the discussion Jeff. Apologize if my initial post came off as grumpy... I'm pretty passionate about the fishery and I think these things are critically important to the future management of our fishery and worthy of discussion, so just dismissing them out of hand gets me a bit fired up. To your last point about not having time to research all the stuff and having professionals... that is what makes it even more frustrating to see a lack of trust in experts. I'll admit up front I am not a climate modeler or expert in abiotic factors. I'm a fish manager. I don't always have the answers and I try to be up front when I'm not a subject expert. But the folks that are doing the climate models and fish production are very, very smart people when it comes to that and I think it's important to take what they say seriously and in good faith. Even those experts acknowledge in their papers and reports that there are many, many uncertainties relating to how climate change will affect biological, chemical, and physical habitat of systems as large as the great lakes. There is so much we don't know about current conditions that stacking future change on top of that makes it very hard to know what comes in the future.

Your questions, which are great:

1) I think it's always very difficult to write about science for the general public without simplifying it, and that's even if you aren't trying to sell papers. That's why it's really important to go read the actual reports and talk to the experts behind the report, rather than just reading the newspaper article. Trust me, natural resource professionals are often frustrated by the end product of a newspaper article or a radio or TV spot. Most people don't care about complexity and nuance, and all the important details are often left out by the time things show up in public. It's extra work, but to be an informed citizen, unfortunately it does take a little more than reading a headline or an article, or reposting a facebook meme at the low end of the spectrum.

3) Yes... the weather is erratic and there are large variations in the short term. Lake Michigan is especially complicated because of thermal stratification and upwellings, which add another layer of complexity when it comes to historical temperature measurements. I don't know what widespread and verified data on things such as ice cover and average lakewide surface temperature exist prior to the "modern" era of science and management, (say 1960s onward) to be honest. It probably exists as a model somewhere given air temperature records, which are much more widespread and go back much, much much further. NOAA is likely the best place for that, and you can see most of their comprehensive data goes back to the 60s and 70s www.glerl.noaa.gov/data/ice/#historical. Surface temperature data back to 1995 is available here coastwatch.glerl.noaa.gov/statistic/

Many things that are critically important to evaluating thermal habitat (i.e. temperature profiles) have very little historical data, since the technology and funding for buoys like the Michigan City Sea Grant buoy with temperature strings did not exist prior to a decade or so ago. Satellite remote sensing of surface temperatures is also a fairly recent technology that is widespread now.

4) Kao's paper states it is using 1964-1993 as a baseline, and comparing to the projections for the 2040s-2070s. Surface temps have been increasing about 1 degree per decade since the 60s I believe, according to various literature cited. So we're a couple degrees warmer (on average) compared to the 60s-early 90s average. The actual raw data/charts are hard to find in studies examining the effect of temperature on fish, because they are typically in a model somewhere, and they are a data input, not an output. I put the GLERL data from 1995-2017 into Excel and the trendline for average Lake Michigan yearly surface temperature (averaged across every single day) has increased about a 1.5 degrees since 1995. The trendline slope is about .07 degrees per year, or 0.7 degrees per decade since 1995.



5) Yes, half optimistic and half pessimistic might be a good way to put it. Changes don't occur in a vacuum, and what is good for one species might not be good for others. Wisconsin for example has measured an increase in largemouth bass in many of their northern lakes, which they believe is a result in warmer water temperature and vegetation growth, and a decrease in walleye. Good for bass anglers, not so much for walleye anglers. There has been some research that shows weak correlations of ice cover and alewife, and reduced overwinter mortality in warmer winters... but the biggest determinant (historically) for alewife yearclass strength was the chinook yearclass strength of the same cohort. IE the more baby kings = fewer baby alewives. Warmer temperatures and increased precipitation and runoff in the lake could mean more primary productivity available for alewife, which would be good... but could also mean that metabolisms of predators is higher due to the increased temps, leading to increased consumption demand, which might or might not offset any potential increase in productivity.

In terms of recruitment, that's where much of the uncertainty comes in. For example, just from an abiotic standpoint (ice cover, water temp, winds etc) it might be expected that whitefish recruitment should increase decades in the future. This paper thinks so: www.researchgate.net/publication/2678983...chigan_and_Superior_. However... biotic factors also play a huge role. We're seeing declining whitefish recruitment in the northern part of the lake, and there is an effort starting to try to figure out why. It's likely tied to changes in the food web cascading from the bottom up (mussels). Sea lamprey mortality has been shown to increase as water temperatures warm, and lampreys in Lake Superior have gotten bigger and more fecund (reproductively viable) as water temps have warmed. So that could be an issue as well.

Another factor apart from average yearly water temp is the specific timing of warm ups in the spring and cool-downs in the fall. Some species are critically linked to plankton bloom, such as perch. Some research shows that the timing of perch larval hatch coinciding (or not) with the plankton bloom is crucial for recruitment. Even a week or two in either direction can miss the bulk of the plankton bloom, which is one reason why perch recruitment can be boom or bust. The 2015 spawn (after a cold winter) likely hit that bloom just right, and all those larval perch got on food right away. Research has shown egg quality tends to be higher for perch during colder winters too

Here's an exerpt from a paper talking about climate effects on fish recruitment

climate-induced warming can alter the timing of
spawning. For example, Lyons et al. (2015) documented earlier spawning in Lake Michigan yellow
perch in response to an earlier spring onset, with spawning advancing by 1.8 d to 6.8 d per decade since the 1980s.
Similarly, Farmer et al. (2015) and May( 2015) documented earlier spawning for Lake Erie
yellow perch and walleye, respectively, following warm winters with an early spring onset relative to
cold winters with a delayed spring onset. Lyons et al.(2015) also provided evidence to indicate that Lake
Michigan lake trout spawned later during the fall during the past several decades, which matches
theoretical expectations associated with a longer fall growing season (i.e., delayed winter onset)

Most notably, a climate-driven alteration of the spawning time can lead to mismatches between newly hatched
larvae and their planktonic prey (Durant et al.2007; Thackeray et al. 2010, 2013). This mechanism was
posed as a possible reason for consistent failed yellow perch year-classes in Lake Erie following short, warm
winters, in addition to the negative effects of a short winter duration on egg size and hatching success
(Farmer et al.2015). Specifically, Farmer et al. (2015)
showed that, although yellow perch spawn earlier after
a warm winter (and early spring onset), the shift was
somewhat constrained (advanced by about 1 week)
relative to the shift in the thermal regime (advanced by
about 3 weeks). In turn, following a short, warm
winter, yellow perch larvae may hatch too late after the
peak in zooplankton production to allow for sufficient
feeding to promote recruitment to the juvenile stage


In plain english, following warm winters, perch spawned about 1 week earlier than normal, despite water temperatures being advanced by about 3 weeks. That 2 week mismatch could be crucial

However.... note that warming surface waters could lead to earlier thermocline formation (stratification) which is useful not only for fishing in terms of finding fish, but it acts as a barrier to wall off mussels from filtering the upper water column, where phytoplankton are creating the base of the pelagic food chain. It's very possible that mussel impact could be mitigated a bit by warming water. Although the caveat with their metabolism increasing applies here too.

Spring is a period when the larvae of many
ecologically and economically important obligate
zooplanktivore fishes are in high abundance (Ludsin et al.
2014). Because thermal stratification is expected
to start earlier and last longer in large lake ecosystems,
including the Laurentian Great Lakes (Kling et al.
2003), the ability of quagga mussel grazing to suppress
phytoplankton production during spring would be
expected to decline. In turn, zooplankton availability
to larval fish during the spring could increase, through
bottom-up effects (Bunnell et al.2014).



7) I think one of the hardest thing about increasing temps is that the eye test is really not that useful, since we're talking about small to modest increases over a long time period, and there is a lot of variability. This is one of those cases like you referenced when you have to trust the professionals that have extensive data sets and know how to interpret them. Here's a good overview of the Great Lakes region glisa.umich.edu/climate/temperature. The great lakes are by and large increasing in temperature faster than the air temp increases, because of the albedo effect I mentioned in my first post. With warming air temps and warming lake temps, there is less ice cover. Ice and snow cover reflect sun energy. With less ice and snow to reflect sun energy, the lakes absorb more of that energy, and warm up quicker in the spring and as a result cool down slower in the fall. Leading to less ice, and a positive feedback loop


Incidentally, there's lots of stuff from MSU that basically says all the same general things as this Purdue study. I'm not sure where that perception there is conflicting information is coming from...? Yu-chun Kao is at Michigan State, and that is referenced in the Purdue study. The 5 to 6 degree increase in summer surface temps in Lake Michigan is coming from Michigan State paper.

Here's another paper out of MSU talking about great lakes water temps increasing, for example
www.researchgate.net/publication/2441852...etween_1968_and_2002
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Lake Michigan is warming. New report says that could mean trouble for game fish Sep 19, 2018 1:18 pm #21291

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One more note to conclude - please keep in mind that many / most of us have full time jobs and families. Trying to research all of this is often next to impossible. We do not experience it daily and real information is hard to find - so we are definitely counting on some of you experts to inform us and look forward to that.


100% agreed, which is why I don't understand how folks can just dismiss expert opinions and research. Challenging them is great if there is conflicting evidence that can be presented. Dismissing them completely and saying they have no idea what they're talking about without presenting a counter point or contradicting evidence / statistics is asinine.

I don't see that very much on this forum. Facebook on the other hand, there's a lot of it...
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Lake Michigan is warming. New report says that could mean trouble for game fish Sep 19, 2018 8:08 pm #21299

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Good stuff Ben. Thanks for taking the time to post all of that.
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Lake Michigan is warming. New report says that could mean trouble for game fish Sep 19, 2018 9:24 pm #21306

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Do any of these studies take into account the periodic shift in the Earth's tilt do to wobble and the trail the Earth takes on its eliptical path around the Sun? I would think that it could have as much of an impact on the environment as, say hydrocarbons. I would think also these effects would be rather long term but sooner or later will change when the next shift occurs. What I am thinking or implying is that the temps can go the other way too.
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Lake Michigan is warming. New report says that could mean trouble for game fish Sep 19, 2018 9:52 pm #21307

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I believe the shifts you are speaking of take a very long time.. AKA 100,000 year problem.

earthobservatory.nasa.gov/Features/Milan...h/milankovitch_2.php

en.wikipedia.org/wiki/100,000-year_problem

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