Not trying to kick a dead horse here, but with a river this small you could clear out the fish in one day and ruin a fishery, that's why our town try's are hardest to protect the fish while there spawning.
The spawn only lasts around a week, if the weathers consistent, so we got locals that take shifts watching the fish day and night, so far so good.
If they make it through the spawn, it only gets better each year, but you can literally ruin a fishery in one day if people kill spawning fish, we have been lucky so far.