I assume that you do not fish with nets, but are a sport angler using some form of line.
If you are, I doubt that you would have a great deal of impact on overall fish stocks. As numbers decline, the remaining individual fish would become more difficult to catch on a line.
The main problems of overfishing are due to indiscriminate fishing using nets which remove ALL sizes of fish, and do not allow the smaller ones to reach maturity and breed.
Geoff the Duck.