Although I believe that the Fraser sockeye management up to the 80s was probably the best salmon management on the coast they did (purposefully) over harvest some minor stocks to obtain full use of the major ones. This could change as Canada seems to want to shift sockeye (and maybe all salmonids) harvest to the FN fisheries which tend to be in-river and can be more surgical in removing just the target stock.

Even if we had no hatchery stocks (or no wild stocks) there would still be the need for differential harvest rates which could result in surpluses at some locations.