Back on my birthday in 2006, I had a post about fishing as a cause of evolution in fish stocks. The linked article at the top of this post dances around the implication, saying that fishing makes the age structure of a population “dynamic” and “unstable”, but they keep a relentlessly ecology-only mindset on the issue. Nonetheless, the answer remains the same so far as regulatory policy is concerned.
Fishing typically extracts the older, larger members of a targeted species and fishing regulations often impose minimum size limits to protect the smaller, younger fishes.
“That type of regulation, which we see in many sport fisheries, is exactly wrong,” said Sugihara. “It’s not the young ones that should be thrown back, but the larger, older fish that should be spared. Not only do the older fish provide stability and capacitance to the population, they provide more and better quality offspring.”
If you want a population to produce bigger fish, you need to stop taking the very biggest fish available.