I am just curious, why Harrision whites, which are not much favoured among many fisherman, were so widely introduced into many lower mainland rivers.
In a nutshell, it is because most LML streams are very poor in nutrients - the Chilliwack/Vedder in particular.
The Fraser fall-run stock group (where the Harrison stock comes from) is unusual because the fry migrates to the estuary immediately upon emergence from the gravel. In the estuary, they rear for three to six weeks before moving offshore, rather than spending 90-150 days in freshwater as is typical of most other stocks with an ocean-type life history.
The sooner they get the hell out of a sterile river, the more they increase their chance of survival. The more chinook come back to spawn and die, the more nutrients they will provide to an otherwise nutrient poor river.
Other stock wouldn't stand a chance to establish a sustainable run.
Simple, eh?
So, look at white springs in a more positive light. They actually help sustain all the other species in the Vedder that we like to catch.