If you look at the Beaver, Chatterbait and Basstrix baits that have patents and are knocked off by everyone it doesn't seem like the time and money spent to patent a lure is worth it. And that is just the beginning. Enforcing the patent is another issue altogether.
I think you get your big bang in the first year and once everyone sees it is a good bait, the knockoffs kick in full force.
So, that leaves you with how to make a lot of baits in the first year. Evaluate your own capacity and take the full profit or share it with a big company and get a percentage of sales.