Back in the 60's we went up to East Tawas and walked out on the pier (as usual) and there were alewives all over, dead and dying. The smell was atrocious and supposedly that was one main reason for planting salmon. Took a few years but the die offs diminished to almost nothing.If I remember right they have a yearly die off about this time of year. In the 60's the beach would be whith with them. Then after the salmon was panted that slowed down a lot but there were always a few wash up
There must be a plentiful supply left as I remember reading an article (I believe on here somewhere) that the alewives prey on juvenile perch and walleye. That is second hand information so take it for what it is worth.