TOPIC:

Do you believe the surface temps being reported for the south end? The bulk of lake Michigan is still around 39-40 degrees at the surface according to the satellites.

If we don't get down lower, will this affect whether the coho move in close to shore in the spring? 

I doubt those are accurate temps. Cloud cover really messes with them. There's ice floating around on parts of the lake right now.

tgftp.nws.noaa.gov/data/forecasts/marine..._shore/lm/lmz046.txt

Text forecast has measured temps (water intakes) and they are 32 and 33 degrees


I'd be optimistic that coho abundance will be good, given that there seems to have been a decent alewife hatch last spring. But personally I think that predicting how good the spring coho fishing will be is about as easy as predicting what the weather will be like in mid-March. I can tell you it'll probably be warmer than early January.... but it could be 60 and sunny or it could be 35 and snowing

I generally did not trust the satellite temps either because they always seem to read wrong. 

There's another source though that corroborated the satellite and the intake temperatures, which I pasted below. The cold water is concentrated near shore (similar to how it warms up faster near shore).

www.glerl.noaa.gov/res/glcfs/ncast.php?lake=mih

Let's pretend the lake is actually 39 degrees over most of the surface - would it affect the coho's proximity to shore in early spring if we went through the whole winter that warm?

One of the biggest reasons coho are close to shore is the relative difference in water temp. So one of the key factors is how fast the shallow south end warms up relative to the other parts of the lake. One factor in why they are unpredictable, given that spring weather patterns influence how fast the lake warms up

Others are bait availability, water currents, clarity, etc. And of course overall coho abundance. I've been here just over a decade and seen warm winter years with terrible fishing, cold winter years with terrible fishing, and lights out spring fishing after warm winters. 

I think cold winters are the best for shore guys, because that usually means the absolute warmest water is the harbors, but for boat guys I am not super convinced that winter lake temps/winter severity is a surefire predictor for how good the coho season will be. 

For example, just last year was the best coho catch rate in at least 2 decades for boaters, and it was a super mild winter

This question might have been covered previously. Is there data comparing lake water levels to catch rates or fish size/health?

I don't think it has been looked at that hard, because there's not much reason to believe that water levels drive much of anything in the grand scheme of things. At least in the ways most anglers bring up a theory (such as higher water = more nutrients). On face level, the opposite is true, given the 2010 and 2012 yearclasses of alewife are the biggest in recent history, and came at some of the lowest lake levels. 

By far the overwhelming factor in salmonid size, growth, and body condition is alewife abundance. We're talking like 75 to 90% of body size can be explained by alewife abundance - about as a direct of a correlation as you'll find in the natural world. And alewife production is mostly driven by the water temps and/or spring/summer zooplankton abundance, which are very linked as well. Predator prey balance is the other half of the equation. Fewer salmon + more alewife = bigger, fatter salmon. And vice versa. 

In short, alewife production is mostly driven by water temperature/profile, which is in turn driving zooplankton abundance. And salmon abundance is linked to alewife abundance. The balance of those populations drives body size of salmon. 

Last years coho were the smallest ever.

I didn't have the success of one of the charter boat captains I talk to but he had a good number of double digit pound coho last year.

Actually, the 2020 spring cohos (March/April) were the smallest I can recall. In an average year, I might have to measure one in every 25 or so cohos (and many of them end up being just over the minimum size.)  In 2020 in March and early April, I was releasing about 1/3rd of the fish due to size and measuring probably 2/3rds. Only about 15 or 20 percent were what I'd call "normal" sized.  On the other hand, in the spring of 2000 we were catching limits of 3+ to 4+ pound fish in March and 10 pounders in early May.