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One of the last times I was out (1/29) I got coho and a 17lbs laker.  When cleaning the laker, I have never encountered so many freshly consumed bait fish (aprox 100).  There was one goby, a couple of perch/crappie minnows and the rest were alwives.

Must of been pretty small alewives.  That's good!  Most of the ales I've seen the last couple years were big and bigger.  

Those lakers have been out there yearly. Post spawn wovles. The crappies are getting hit when the wovles move up to the Y. That has been happening the years when bait was slim out front. Just goes to show what one laker is eating. Just like wovles they are eating and expanding their range. Time for a 5 fish limit on Lakers. Federal tax money put them their. Jullians is producing at 70% natural reproduction,and Waukegan reef not that far behind. If this area isn't ready to move to a 5 laker limit then the question to be asked is what point and at how much natural reproduction is needed?

Dissapointing to hear the trout are gorging themselves on the only food the Chinook and coho rely on.  Now that the hot dog sized Gobies are all gone I find it hard to believe the trout waste their time chasing the little 1 1/2" fish in the rocks in front of the port.  

I was writing an article for a Michigan magazine last year and talking to a Michigan biologist. He said the lake trout eat 95% of all the gobies in Lakes Michigan and Huron EVERY YEAR!  Hard to believe a population can survive at that level of exploitation. Seems like a few specimens ought to live long enough to die of old age.  Hard to believe the 5% of the survivors can repopulate the lake to the point the amount of gobies showing up in predator fish diets is even measurable.  

BNature wrote:

I was writing an article for a Michigan magazine last year and talking to a Michigan biologist. He said the lake trout eat 95% of all the gobies in Lakes Michigan and Huron EVERY YEAR!  Hard to believe a population can survive at that level of exploitation. Seems like a few specimens ought to live long enough to die of old age.  Hard to believe the 5% of the survivors can repopulate the lake to the point the amount of gobies showing up in predator fish diets is even measurable.  

The biologist was probably talking about total mortality, not really possible to separate out how many would die of old age vs how many get eaten. But the high mortality is why the top-end size has gone from 6-8 inches down to most fish being under 5 inches. They're so prolific that they are persisting despite everything eating them, from bass to whitefish to lake trout to browns

This is probably the research that was being referenced 
experts.illinois.edu/en/publications/age...an-with-preliminary-

Takeaway was:

 Based on catch curve analysis, estimates of annual mortality rates ranged from 0.79 to 0.84. These relatively high mortality rates suggested that round gobies may be under predatory control in Lake Michigan.

One does have to wonder if their population is sustainable at that level of exploitation. Not that I'm suggesting a return to millions of 6+ inch gobies that are too big for perch and bass to eat, that are incredible nuisances for perch anglers... but gobies are a significant portion of the forage base for quite a few different desireable fish species.

I think Mike's right with the theory that these fish are adults that came to spawn, and then stayed because of favorable food and water temps. There are typically very few wild fish or small fish in the mix during the winter, and most of the tag returns we've looked at have been legacy Indiana stockings from awhile ago. In fact, there are VERY few wild fish ever picked up by our late fall or early spring netting. And then all of a sudden the summer collection of angler-caught fish are 40% wild - so those wild fish are not sticking around Indiana waters overwinter for whatever reason.  I would speculate that they are overwintering near their natal origin (Illinois reefs most likely)

Btw, a lot of the "alewife" pictures from lake trout bellies this time of year turn out to be juvenile gizzard shad. Lots of them in the Port and other harbors and tribs. Usually the lake trout we catch in the fall are stuffed with 2-4 inch shad, along with gobies and a smattering of random other fish. Occasionally you'll find alewife but it's not terribly common compared to gizzard shad. 

If they are gizzard shad is that what the cohos are feeding on also?

Actually, while the lakers are likely eating any gizzard shad they happen to encounter while they are inshore over the winter (or where ever) it's unlikely the cohos near them are feeding on the shad.  For one, by now baby gizzard shad are likely five inches long or longer. Not that a fifteen-inch coho can't - won't - eat a 5 or 6-inch prey fish but they'd likely choose to eat three-inchers. 

The key is "choose to eat".  I've cleaned litterally thousands of cohos in February, March and early April. I can probably count on my fingers - don't need toes - the number of baitfish I've found inside their bellies. These are fish from the ship canal (loaded with shad), inside the Port when fishing in there was legal, back when alewife numbers were at their peak, since gobies came in the lake, back when there were smelt..... I'm not saying it never happens, but it's very, very, very rare. 

It's not that I'm catching fish from places where there is no bait, although I catch plenty of cohos in places with hardly any bait in the spring. In March, it's unsual to see any bait schools along the Inland wall or at Cal Park or even at the Gary USS landfill, but cohos are there. 

The fish are there because the water is a few degrees warmer (or several degrees warmer in the Port or ship canal), not because of any minnows that may or may not be there.  

If they have anything in their stomachs it's teeny-weeny black bugs of some sort - more slime than substance.  

I really believe most of these fish which have lived in the lake for 14 or 15 months and have never eaten anything but bugs. I really believe for some of the cohos I catch, the ThinFin, J-9 or other lure they bite was their first attempt to actually eat another fish. Oops! 

I don't know if their switch to actually eating fish is triggered by instinct, water temperature or just something that clicks when sometime in April they find themselves swarmed with spawning smelt/alewives.  I do believe if once this switch flips - if there were a bunch of five-inch  shad, goldfish, or most any other kind of prey fish around, the cohos will snarf them. 

Thank you very much Capt . I appreciate your sharing of knowledge. The whole thing kinda blows my mind! 

Last,winter a lot of anglers found the coho's in the ditch. As I was one of those I saw a lot of shad while fishing. Found a lot of shad inside the coho's we caught. It seemed that if you saw the schools of shad you had a better chance of getting some coho. 
Now this year is completely different. The water is colder in the ditch and there's NO coho to be found. Sorry to day.