Throwing the Little Ones Back
Throwing the little fish back, a common practice, causes fish to shrink over time since there is selection against the survival of larger fish:
Survival of the Smallest, Ecology, Scientific American: Any commercial fisher or weekend angler knows to “throw the little ones back.” The idea is to give small fish time to grow up… But that strategy may actually be harming fish stocks. Ongoing experiments on captive fish reveal that harvesting only the largest individuals can actually force a species to evolve undesirable characteristics that diminish an overfished stock’s ability to recover, says David O. Conover, director of the Marine Sciences Research Center at Stony Brook University. The results may explain why many of the world’s most depleted stocks do not rebound as quickly as expected.