hey not sure how to say this.....putting chum eggs in a coho river(or any river) is not good....chum spawn the latest of all salmon, and wipe out the nests of all the other salmon....here on the island, rivers r short, springs and coho have nowhere to go...since we have intoduced chum to the cowichan, goldstream, sooke rivers, they have taken over and r the dominant fish return. adding chum to a river, could have catastophic results...
What makes you state that Chum are an introduced species to these rivers?
Chum fry don't stay the rivers after hatching. Coho fry do and often benefit by backwaters created by beaver dams etc.