Sg - I agree. However, there is a line of evidence that is developing that suggests that body size in adult Pacific salmon on the spawning grounds is, and has been, a competitive advantage. And that by NOT selectively spawning the larger adults (M/F), we are unintentionally reducing the size of the subsequent adult offspring.

The theory goes like this:

On the spawning grounds, large males tend to outcompete smaller males for the "right" to spawn with whatever female is there. Larger body size and aggression have alot to do with that. Ditto for larger females. They produce larger eggs (which can produce larger fry, which then have a competitive advantage in the stream) and they can dig a deeper redd, which protects the eggs better than a shallower redd. Either way, a large body size on the spawning grounds is a plus for adult Pacific salmon.

However, there is a counter-acting competitive pressure in the ocean. In order to grow to a large size, the adults need to spend proportionally more time in the ocean (duh). As we know, the ocean is a high risk/high reward environment. The longer they stay there, the bigger they get, and the larger the competitive advantage when they spawn. But the longer they stay there, the better chance they'll get eaten. So, there is a competitive advantage to those adults who don't spend much time there since dead adults (e.g., consumed by orca) can't spawn at all.

So, there may be a zing/zang to the competitive advantage and disadvantage of a large body size. Now, if we take away the large body size advantage in the hatchery environment, by NOT intentionally spawning larger adults, the genes for a longer ocean adult phase are lost. But the competitive disadvantage of the ocean phase remains. Indeed, it might be considerably larger since human harvest is a major contributor of adult ocean mortality. The result is that we may be losing the genes for longer ocean phase, and a large body size, by non selective spawning in the hatchery.

Indeed, a smaller adult body size is apparent to alot of folks, and not just to fish biologists. But I will not subscribe a reduction in body size to current hatchery spawning practices just yet. However, I don't think we fully understand the impact of (almost) random mating in the hatchery, since that is NOT what happens in the wild.

I welcome your thoughts.......