Within three controlled groups of the same species of fish, harvesting was done over four generations. In the first group, only the largest fish were harvested. The smallest fish were harvested in group two, and in group three, a random harvest was performed.
The results indicated that the later generations of fish from the group where the smallest were harvested actually grew larger than their predecessors. The fish in the large harvest group produced smaller offspring, and the random harvest group remained status quo.
The study indicates that it only took four generations of evolution for the "large" fish genes to begin producing larger fish, and the small fish genes to produce smaller fish.
What does all this mean for our fishing efforts? After all, this was a very controlled environment, and the study only dealt with one specie.
If the study proves to be valid, this could mean that changes in harvest rules and size limits could not only increase recreational and commercial fish stocks, but could actually increase the average size of harvested fish.
Several years ago I was doing an article on freshwater bass fishing in a small impoundment in Georgia. The fisheries biologist I interviewed shed some light on another aspect of this issue.
He was studying the catch and release policies that most bass tournaments - and now saltwater tournaments - practice. His information showed an overabundance of smaller fish in most impoundments. He also determined that the reason was linked to the catch and release practices. No bass angler worth his salt would keep or harm a tournament fish - they are all released alive. Yet the trophy fish - all those big enough to mount - were kept. This biologist's effort was to have anglers harvest some of the smaller fish for the table, leaving the larger fish to repopulate.
I suspect he was not aware of the study being done by Science, but it appears he may have been on the right track. I have seen stocks of fish depleted to an alarmingly low level and then seen that stock increase four fold when strict management rules were put in place.
Perhaps it is time to place some maximum size limits in place on our catches. In Florida, as an example, a harvested redfish must be eighteen inches long, but it also can not be longer than twenty-seven inches. This slot rule leaves the big brood fish to produce more offspring. Perhaps this study indicates that in addition to leaving the brood fish, the policy may also be creating a larger average size of fish. Only time will tell.
Until then, try taking a picture of that big fish you just caught and then release it to produce more fish. Keep the smaller ones to take home and eat!
