I carry my inflatable kayak, gear and 4-piece fly rod in my bike trailer. I usually use one of my Mountain Bikes to go to the streams around here. I can also haul my camping gear. I also have a gun/bow rack for the handlebars, and have brought many deer and feral hogs/Russian Boars home with the trailer. I have hauled as much as 100 pounds on it (it may hold more, but I don't feel like pulling any more than that...). There are trailers that hold a lot more.
A four-piece fly rod in a case fits in a pannier or handlebar bag very nicely. You can use rear panniers to carry waders, fly vest, boots, etc....