Just remembered a fish hatchery in Izhuit Bay on Afognak Island. They store their floating fish pens in a small cove near the hatchery. The web is taken off the pens so they are just floating frames made with large diameter PVC. The returning silver salmon spend a bunch of time milling around under the pens and we used to fish for them there.

Problem is a hooked fish can go to any pen it wants... And having your hooked silver jumping several pens away could be stressful! Saving marginal fly lines just for use there is mandatory... Lots of line-mangling nails and junk hanging off the pens...