Store bought pollock, Canadian walleyes are too good just fried!!
Pollock is very wet fish and you will want the skin on it. That is not the way it is usually sold.
Hypertonic brine of kosher salt and brown sugar, 2:3 cups of each per gallon.
With soft fish like pollock and black cod it is critical the brine be as cold as possible.
Brine for 90 minutes rinse under cold running water for less than a second, just enough to get the obvious stuff off the surface.
Place on smoker racks and use fans to dry the surface and form a pellicle. This is the single most important step and it is critical. Pollock must lose some water before it will produce a decent product. The pellicle must be glassy and stiff.
Put it in the smoker with very low heat and quite a bit of smoke. If it is more than about 100F the pellicle will probably crack and you just wasted your time... after an hour or so you can bring the temp a little over 100F for about an hour. The fish should not feel soft. If it does take it off the heat and put the fans back on it.
When it firms up you can put it back in the smoker. Go to 130 for an hour or so. Do not exceed 140.
When you take it out of the smoker you need to lay it on absorbent material like brown paper bags to cool. Then wrap loosely in paper towels and put in baggies in the frig.
I have smoked a lot of it and it takes some effort. It should be firm, flakey, and very good. It will be delicate and hard to handle.
Brining for more than 90 minutes does nothing good for the texture of fish. Studies at the Fish Tech Research center in Kodiak have shown it is the way to go.
