Yeah most yak fishos I know have the manual inflation yoke type. Most have never had the need to use it - but it's there if you need to.
The other learning from some yak fishos (from actual experience) is that should you go into the drink, carefully consider whether you need to inflate the PFD. The issue is for when you are trying to get back in/on your kayak. Having a fully inflated PFD makes it very difficult to manoeuvre your body to get back on the yak, as you would generally pull yourself onto the yak on your belly and having a big balloon on your chest is not helpful. General advice if to stay with your kayak, as it generally has boyancy built in. Try and get back on if you can. If you can't still stay with your yak and dog-paddle into the shore.
Cheers, Pete