Geographically the ODNR makes their yearly survey trawls in the same area's and water depth's year after year. In 2011 the algae blooms were extremely bad from the wet spring! Those little eyes are no different than any other life form on earth. What would you do if you could breath but not get enough oxygen to maintain a quality life not to mention the smell that must be in the water from that nasty stuff affecting their ability to locate prey. You along with any other creatures who have survived and multiplied over centuries of time would move to a more friendly environment. To me that is why the state missed the hatch survival rate in both 2010 and 2011, those year class eyes moved to a more environmentally friendly area of the lake where the ODNR does not do their survey trawls.

With all of the rain at this time and earlier this year I feel that everyone who fishes and or uses the lake for other forms of recreation should be prepared for a major algae bloom or blooms later this year. At this time we have the Maumee, Portage, Sandusky and Huron River spewing all of that farm runoff into the Lake, not to mention every minor watershed such as the Toussaint and any other small creeks feeding directly into the lake. On top of that some of the sewage treatment plants located along those rivers and streams feeding into the lake have most likely already overflowed into the drainage system compounding the problem even further. So I think the State ODNR will most likely miss the hatch again this year. The perch fishermen and the minnow boats will start to see those 2013 YOY walleye in mid to late August if they exist.
These are just my thoughts on the subject and not based on anything the scientific community would support but they are based on past experiences over my many years of fishing Lake Erie.