http://www.mlive.com/news/index.ssf/2016/04/michigan_chinook_salmon_collap.html
 

Psssssst- it already did.

I don't think a collapse has happened yet rg but the lake has changed for sure and it seems due to a shortfall of YOY alewives.
The spring trawls will indicate how bad or a rebound .
If they show bad , then it will be alarming in the next few years .
I'm already preparing to target lakers more as the goby will sustain their feeding habits and they will , already grow huge .

Ps,
This is why I asked about the inquiry from stat of lake meetings in their focus on invasive.
Goby and zebras. That should have been the main focus.
There seems to be zero control

There are no effective control strategies for either the mussels (mostly Quagga now, bigger and deeper) or the gobies, although the shags have switched over almost completely to gobies. 

Smallies like to feast on gobies too.
 

I know it's to late in the game but regulations need to be implemented on sea going cargo vessels that require them to have intake filters and grinders on their ballast tanks.
Why are they only focusing on the recreational boaters and not the real problem?
I also know in Lake George, they have started putting mats on the bottom of lake to try and smother what clams they have found. Now obviously, the Great Lake would be an almost impossible task but we have to start somewhere.

As for the goby , no idea other then predation as a control aka lake trout.

All predators when the temperature windows allow.

Yes it was mentioned that almost any  fish that are in the same depths/ habitats will eat Gobies. When and if they are in the same place as salmon or trout they could be dinner.  I know bass, walleyes and pike love them.