Good stuff Wolfgang
Beardlesee {your author }writes of seeing a trout seizing the salmon eggs
from the breeding female and perhaps causing the wounds which are
frequently found on the female salmon's belly after spawning.

I'm currently enjoying reading "Explorations of Kamchatka 1735-1741 ". The
author claims the Russian salmon were so driven to move upstream to breed
that when too

exhausted to fight the current they would bite onto a fresher fishes tail
and be pulled thru the heavy water. The natives said you could see the
wounds on many fish tales. ----[sounds like a fish tale to me]
However when I fished a small stream in 1993 the salmon were so thick that I
could not get a fly below them to catch the rainbow swimming below and
feeding on the eggs. I just had to catch the25 inch salmon on my five
weight armed with a wooly booger.
Joe the Elder--have photo proof !