Most people I know have a least a small amount of duct tape with them on any fishing trip. I personally wrap a foot or two around my rod tube for any situation that might arise where it’s needed. Because if you can’t duct it, then….
Another handy item I’ve found to be indispensable on many fishing trips near and far are zip ties. Some people also call them cable ties. But everyone knows them as the nylon strip that has teeth that face in one direction.
I’ve used them to fix many a broken zipper on my fishing bags, waders, packs, etc. I’ve used them to hold together a shattered rod ferrule (the female end). Zip ties have also held larger guides on my rods for embarrassingly long times. They’ve bonded the rubber together on my boat and worked as a makeshift patch for larger tears in backpacks and travel duffels. I’m sure there’s an almost infinite amount of uses for them on any fishing adventure, just like the indispensable duct tape. So do yourself a favor and get a couple different shapes and sizes and chuck them in your fishing bag. You’ll thank me for it later.