Unless you have a super deep freeze that sits at absolute zero there is no merit to the freezing for 30days thing. I have jerkied bison right from the butcher and I am still here to tell of it. You can jerky anything but different meats dry differently. Fish and poultry needs to be fully dried and as such is quite tough. Duck on the other hand doesn't contain salmonella so it is similar to pork in that you can leave more moisture in it. Beef/bison/venison are the best for tenderness. I still recommend freezing the meat first as I find the jerky to be much more consistent and less gamey (sp?).