alt Hacker News> it takes thousands of years in a minimally interrupted state for such diversity to come about in nature
The article says it only took 30 years to kill off all the big cod by only allowing the generically-smaller cod to escape and continue breeding. Now that all the eastern cod are protected, maybe it will only take 30 years for the gene pool to return to normal size distribution.
I'm pretty sure it doesn't work like that: previously there were genetic variants for large and small sizes. Now a high proportion of the larger variants have been removed from the gene pool. To reverse that in a similar time frame would need a massive selection pressure on the smaller variants. So you would need something like industrial scale fishing that removed the smaller adults, but didn't take out the juveniles who would become big fish, while also letting go the bigger adults. It doesn't sound feasible