"Shrinking at Sea" is an article in Science News that says, "Commercial fishing is generating a 'Darwinian debt' in the form of less valuable fishes," because of industry gear that catches bigger fish and leaves less productive, smaller fish in the gene pool.

Changes in genetic stocks can happen quickly and could take many generations to correct, according to the weekly Science News.

Researchers demonstrated the negative evolutionary effect by mimicking commercial fishing in six aquarium tanks. They periodically removed larger fish and tracked a gradual genetic change to smaller individuals. Then they noted an opposite trend toward better reproduction and larger fish after they periodically removed smaller fish.

Fishery managers in recreational angling have long noted the genetic consequences. In freshwater bass management, for instance, "trophy bass lakes" have been established by allowing liberal bag limits for small fish, but a no-take policy on large bass. Saltwater fishermen face zero-bags on large snook and redfish for the same reason.

FS