At one time there was an effort to use net pens to keep coho and Chinook in PS. The delayed-release program. Seems to work rather well at keeping them in-Sound. The fish, since they never went to ocean, were rather small. Also, there would need to be a good food supply even for the smaller fish. I think, if memory serves, that the fish were released in the latter part pf summer and really seemed to enter the fishery in winter as about 12" fish and growing.