If they are going to screw with the laws to any extent, why not make it a uniform size for both male and female and 16cm for both, 2 females and 3 males, or 5 males?
By raising the min size it would ensure a better number of breeding cycles before harvesting and in three years the average size will attain the new legal size for the majority.
The jewfish certainly have not suffered from raising the minimum size limit, nor have the snapper (they could go to 45 IMO).