Fish populations need to be pretty heavily protected so that they don't get wiped out. They need time to reproduce for them to continue being a source of food in the future. While many fisherman would exercise common sense with softer regulations, some would go for the quick cash grab and destroy the ecosystem. That isn't acceptable.
Fishing regulations are not very restrictive at all. In fact for the preservation of future generations fishing regulations could very well be increased. First their is no internationally recognized fishing regulations. This allows Japan to continue to harvest whales despite their rapid decline in population. Furthermore scores of reports from across the United States fisheries have shown that there is much less fish in our areas of the ocean than even fifty years ago. At the current rate of fish consumption the populations may never get back to where they were.