Why should you get rid of nets even though you have plenty of fish? Fish caught by nets are worth a lot less to the economy than fish caught by sportsman. Show people how increasing fish numbers is important for the tax base, and you'll get the wild fish back for free.

On the other hand, even if you restrict the number of total fish caught by netters, you won't be able to eliminate wild fish being netted. One net can wipe out a wild run even though the some total of all of the nets looks "ok."