Been fishing toothpicks on and off for 18 years in my herring/chovies.

I don't know if a salmon can pass them, but I watched a dude on my boat grab a pre-rigged herring one day and swallow it (like the goldfish swallowing contests in the 50's)!!!

He called poison control and they said he'd pass it in a day or 2. He had it in him for about a week or so, until it perforated his intestine and he "went septic". Nasty scar he ended up with as a souvenir for being stupid. The toothpick was unchanged, just jet black.