My two penneth for what it's worth:
1. Commercials - I'd make it illegal to throw anything back, what's sizable gets sold, what's not gets sold as pot bait or feed or fertilizer or whatever - better that than being thrown back. Once the quota's reached, tie the boat up.
2. Fish Size - keep the little ones and put the big 'uns back. Little ones taste nicer, imho.
3. Bag limits - interesting one....I counted up the fish I caught last winter......a massive.............12 fish, but they came from 5 sessions with one blank. A lot for a winters fishing?? Of course not but if the bag limit had been two I would have had to put 4 back (two in the NESA comp). I don't believe our best anglers fish every night, they fish when they're most likely to catch. Even if I lived in Cullercoats I wouldn't fish from March to September.
4. Lack of bait - two sides here I think. Firstly the digging out of bait from various beaches no doubt has an effect on fish that could potentially be caught at high tide but none of the worms that "live" in the holes we fish at low tide get dug out , they only get washed out when conditions are good (I'm no expert on the movement of lug and rag up and down the tides).
However, secondly, I do know that crabs peel in shallow water and disappear when it gets colder and the more we take during the moult the less there will be in the future. When I was young you'd catch red codling in most of our rock end holes but not any more. Perhaps the number of people now freezing down crab is having a devastating effect on fish, inshore, feeding in the summer. Perhaps that's why there's plenty a mile offside (like Van Niestelroy lol)
5. Lastly, when I was younger and the tides were wrong, or we had some bait spare, we'd often put some sets down - a dozen baited hooks, anchored down near the low water mark, retrieved 12 hours later. We did well, knowing where to set them, but only "profited" once or twice a year. Difficult to legislate for and difficult to police.
No answers but an interesting thread. I blame the 'yakers.