Lake Erie Discussion Board

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The Great Lakes support numerous fishes of ecological, economic, and cultural importance. How will Great Lakes fish communities respond to projected changes in temperature and precipitation?
This webinar will provide information about:
 - Expected impacts of climate change on Great Lakes fish communities
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Agenda
   Welcome and Introduction
Jill Jentes Banicki, Ohio Sea Grant
 
   Climate Change on Great Lakes Fishes
Stu Ludsin, Assistant Professor, Department of Evolution, Ecology, and Organismal Biology, Ohio State University
 
   Question/Answer
Participants will have the opportunity to ask questions via a live chat after the presentation.
 
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Interesting stuff, David.  Thanks for the updates.  Unfortunately in today's agenda-driven atmosphere, there is going to be a lot of propaganda spread around about any issue.  A few questions for you, if you could expound on the information:

What I'm gathering from your posts and articles is that there still is, in fact, a technological issue with keeping up to the NY standards.  While the salt-water vessels may have equipment that is close, it's still being worked out.  Is this correct?  You also state that fresh-water shipping vessels have not made similar preparations, so they are not as close.  But then you note that these laws are only to effect shipping entering the St. Lawrence Seaway from the Atlantic Ocean.  If this is the case, then why is the lack of ballast water treatment systems on the fresh-water vessels an issue with respect to this story?  Obviously it's an issue for inter-lakes transfer, but that is a bit of a separate issue from this particular story.  Do you have any numbers that show how many of the Great Lakes fresh-water vessels have the most up to date ballast water treatment technology, if any?  This would be interesting to see.  Also, I wonder how expensive the technology is, any idea? 

From where does the time-line in your last message come?  Why does is stretch out 9 years when the article you link only talks about an extension through 2013? 

Thanks again for your contributions. 

Hi Bob,

There certainly is some historical evidence that links ice cover with successful walleye spawning events.  However, as you note, there are other important factors and they are all interconnected.  With that in mind, the presence of ice cover probably doesn't directly lead to a successful spawn as much as it may influence some other factors such as temperature and food availability for the larval walleye.  Because these factors are interconnected, it's hard to definitively rank them in order of importance.

The overall health of the spawning habitat is key, because a healthy habitat can help to buffer other factors such as weather events.  Weather events themselves can impact larval fish by increasing runoff, and along with it turbidity and phosphorus.  These may then effect feeding behaviors and food availability as the larval walleyes start out by feeding on zooplankton.  Timing is important.  Even if there is plenty of zooplankton, it has to be available at the right time.  Currents can have a huge impact, because they can either sweep the larval fish in to the protected, productive shallows or the open, much less productive deeper waters.  Wind direction and speed after the hatch will also influence how protected the larval fish will be.  The health and condition of the spawners themselves is important.  High growth rates of adult fish one season seems to lead to a better hatch success the following spring. 

And yes, there is definitely active research in this area.  Much of the information above is supported by ongoing studies by the ODNR-Division of Wildlife, the Ohio State University Aquatic Ecology Laboratory, the University of Toledo Lake Erie Center, and others.  Studies are ongoing exploring the genetics and success of distinct walleye spawning stocks within Lake Erie, movements and migration patterns, and response to improvements of spawning habitat, among others.  It's a very complex issue, and a key focus of fisheries management on Lake Erie.

edit:  a couple of links to similar threads on this site
http://ohioseagrant.osu.edu/discuss/index.php?topic=1075.0
http://ohioseagrant.osu.edu/discuss/index.php/topic,225.html

Update:

I just spoke with the Sandusky Fisheries Research Unit, and the data from the fall trawls are still being analyzed.  Again, when we hear something we'll post it. 

Fred,
One of the reasons for the "better than expected" figure is that the 2007 year class seems to be stronger than initially estimated.  The 2009 Walleye Task Group report estimated the 2007 year class to be 8.3 million fish, but that has been adjusted to 11.782 million age-2 walleye in 2009.  This translates to 8.319 million age-3 (2007 year class) walleyes in 2010, which represents 42% of the population.  For those interested in much more detail, check out the Walleye Task Group reports   There is a brief executive summary, as well as an exhaustive report for 2010. 

Covert,
For forage fish reports that John referenced, see the GLFC Forage Task Group reports.  These reports are from the Great Lakes Fisheries Commission Lake Erie Committee, on which ODNR-Division of Wildlife serves.  According to the executive summary for 2010, Western Basin forage abundance increased in 2009 while Central basin forage abundance decreased.  Again, you can find much more detail if you follow the link. 

Hi Blidwils73,

I've actually heard stories from a couple fishermen that swear they saw or heard walleyes feeding on top, but certainly not like white bass do.  The white bass are biologically built and wired for that kind of fast action cooperative feeding, and that just isn't typical walleye behavior.  Even the stories I have heard about walleyes on the surface didn't involve corralling behavior:  One involved seeing a couple eating mayflies on top in the summer, and another was about hearing them splash in shallow water at night.  The latter would be possible this time of year, as the fall night bite can sometimes be very productive with crankbaits very close to shore.  While anything is possible, I'd say it's pretty unlikely for you to observe this behavior. 

Hi Bob!

It's always tough to try and diagnose something from a just a physical description, so I can't tell you with 100% certainty what they're seeing.  However, it's likely just a common bacterial infection.  The bacteria that cause these types of infections or rashes are always in the water, but the infection occurs when the fish is stressed for some reason which then causes it to be more susceptible to disease.  You'll see the spots a lot of times in the spring when the fish swims up against weeds and rocks during spawning, or when a fish gets caught and released and the slime layer gets rubbed off in the process.  Likewise, this could occur if a fish had been in contact with a net and then released.  I spoke with our friend Kevin Kayle at the Fairport Harbor Fish Research Unit and he noted that autumn turnover of the lake has begun within the past couple of weeks, which is a major source of stress for the fish.  This explanation seems the most likely, as the timing of the stressor matches up with the observations of the rashes on the perch. 

It is extremely doubtful that it is VHS, as VHS is a cool water disease.  The water temperature out there currently is high enough that the virus just doesn't replicate under those conditions. 

Thanks for the question, and good luck out there!