seems it would work

A nice idea, but pretty far-fetched I think.

They use high-tech sonar in many parts of AK to try to count the numbers of fish going by and the species by judging the swim bladder size (what echoes back) ... and they can't get that right much of the time, so it might have a problem with something as simple as an adipose fin.

I like your train of thought, however what percentage of straying occurs even before the fish get back to the hatchery? Some strays can't even get the home river system right.

I think hatchery imprinting needs to be understood/looked at a lot harder as a deterent to straying.

Keep thinking!
Beezer

don' you think a small chip implanted or attached to the fish that could be read by a scanner would work? Cost may be high, but who knows?

Intriguing idea but the biggest fault I see with it is those times during fall salmon migrations when there are often hundreds-if not thousands of fish cramming into the trap at a time. How do you differentiate fish then when they are crammed side by side? Many wild fish could be "zapped" while aiming for the hatchery fish.

All salmon stray, wild fish too. A study I was involved in in Oregon many years ago, one in which tens of thousands of salmon scales were read to determine life history, demonstrated that the stray rate was about 3%. This makes perfect sense biologically, as if a river system got wiped out, like the Toutle after St. Helens, it would never repopulate with salmon if a few didn't try something new.

If you don't want hatchery/wild interactions, only breed hatchery fish that are incapable of spawning with wild fish timing wise.

bad dawg, i read a study in sts, where in the rogue river they caught and put chips in like 35 wild steelies and they could follow them up and down river, really interesting article, the steelies in some cases would travel way farther up river (17 miles) past where they were born, but would swim back down to the spot where they were born..but however it seems there are alot of fisherman down on the rivers who clip the wild adipose with a pair of fingernail clippers then they release them, thats what the article said..