I don't think the people will follow unless govt legislates against it. Moreover, the fine has to be great and it should be executed at least once to show its strength.
HK people has much freedom and sometimes it's overused. They will never be considerate. As I said again, fishing, in general, is a hobby like hunting - killing organisms as an objective (no matter whether you will throw the fish back into the sea to free them). So should we be so naive to believe that they will follow (even the law is legislated, the islands are too remoted for the related parties for execution.)
To cap it all, edcuation is the most important element to change their attitude. But changing their attitude is even harder than legislation.