I see Nate already replied, but if after viewing the video something is still unclear, I'm happy to clarify!
Specifically, the part that should interest you is around here and lasts around 10 minutes:
https://www.youtube.com/watch?v=vIHS-comkvo&list=PLwGl7Ikd_6GTpd2PnWqqIZVsqotxtrtaE&t=6496s
The timestamps:
01:54:55 Generating the mesh for the fishing pole
01:55:45 Fishing rod bones creation
02:00:10 Fishing wire mesh and bones
02:12:20 Wire IK constraint
