I'm one of those left-wing commie pinko alarmist tree huggers!
Back on the days when I resided and fished in Australia, we used to pump ghost shrimps (known as bass yabbies down under), turn over rocks for sea worms, thread a whole live mackerel or squid on the hook for pelagic species, kill small fish and chop them up for bait, etc. Now, I find it extremely difficult for myself to do any of that. I don't have the heart to suck bugs out of their habitat, dangle them on the hook, screw up their osmoregulation while they drift down a stream. I also try to avoid drowning worms. Although such empathy has developed, I'm not going to condemn others from doing so, because every angler evolves differently.
Anyway, back to the original topic. Like all wild populations, it comes down to whether or not recruitment rate stays above harvest rate. The temporal comparison of population should only be determined by biologists, not harvesters. Too often harvesters are convinced that the targeted population has not changed over the years, based on the consistency of harvest. While the harvest amount may remain consistent, the time expended to harvest the same amount may have changed over the years, the harvesting locations may have changed, the ratio of size classes of the harvested specimen may have changed (as suggested by the carp). Without consistent sampling over time, it is hard to determine if our harvest has changed the ecosystem. By the time the changes are realized, it is often too late.
What should be concerned is that harvest pressure may have increased in recent years as more anglers discover the effectiveness of ghost shrimp, while daily quota has remained the same as many years ago. On a more positive note, most of the harvest is concentrated in a few months per year, but how positive that is depends on how fast the population recruits, which I am not familiar with.
There, my Christmas preach.