Great. WIsh I knew what you were talking about. Thanks for bringing up the topic as know I know.
Yes, I am a rookie so I went to 3 different websites. Here's a clip:"Redd superimposition, i.e., spawning over a redd site
where another female has previously laid her eggs, is a
common phenomenon in salmonids. It has been
documented in streams where different species reproduce (Sorensen et al. 1995; Landergren 1999; Taniguchi et al. 2000). Superimposition also occurs among
the individuals of a single salmonid population, ..."
2012 John Wiley & Sons A/S
ECOLOGY OF
FRESHWATER FISH