Fire was changed in the latest version, and that includes smoking. Smoking now requires a daily fire of some size (I don't think the exact requirements have been figured out yet). If you're marginal you'll get some worsening of the result, and as the fires get smaller and more intermittent you lose more and more.
However, if it's winter you can dry fish instead. It takes longer but results in a somewhat lighter preserved piece of food with less work. Drying only works during the colder portion of the year, but you're told when trying to initiate it if it's out of season (you won't just find that everything spoiled).