Interesting indeed, thanks for posting..
A single large fish will simply grow a little when it gets more food, or lose a little weight when food is scarce. A population of many young, small fish, however, may explode in number or collapse depending on food availability.
The author's point seems to be that the practice of taking the larger fish from a population isn't necessarily "wrong" but perhaps allows for less stability across time, where as leaving the re-building process to the young fish, a population, may either explode or collapse at shorter time intervals.
I wonder if these findings differ any species to species?