This psychological technique has been used for centuries among native tribes.
No nets, no gimmicks, and no barriers; just fish psychology. This entire village gathers to herd schools of fish using nothing more than vines.
For one reason or another, these fish will not swim past the vines although there is no physical barrier. These fisherman for a large circle with these vines and slowly reduce the size before funneling the fish into a trap.
They then use harpoons to harvest their catch, allowing them to feed dozens of people. This is a very labor intensive, yet still social activity that can help these groups survive as they have for centuries.