Norm :

Here is the Ohio link and discussion and chart pg. 7 which notes some of the same matters about crowding. I would agree with Bill that this must not occur much because their is almost no discussion of it in the studies. The very limited info I found (was hard to locate) and appeared to be offhanded, as in not a problem.

http://studentresearch.wcp.muohio.edu/april01/fish_sp_miami_basin.pdf