The studies on the Keogh (steelhead) showed that fertilization with either fertilizers of carcasses increased smolt production. At the low marine survivals that were being seen at the time this actually resulted in the runs more than replacing themselves.

The Ford Arm studies in AK with coho showed that productivity chnaged with increasing pink escapement. At 0 escapement, the 60% HR management took 1,000 coho. At 2 kg/sq metre the same 60% HR took 5-8,000.

The fact that the supplementation may not have shown increased production only says that current productivity is being met by the management scheme in place.

Productive Capacity is not a single number. We know that coho can, if populations are high enough and instream productivity is high enough, will produce fry that smolt, fingerlings that smolt, fall smolts, and spring smolts. Lower productivity, lower escapements, and you get spring smolts which, as has been shown many times, will support some level of sustainable fishing.