From the Science Daily
Fewer Fish Eggs, Smaller Fish Result From Over-fishing
ScienceDaily (Jan. 24, 2006) — The practice of harvesting the largest individuals from a fish population introduces genetic changes that harm the overall fish population, a UC Riverside graduate student and colleagues have determined. Removing the large fish over several generations of fish causes the remaining fish in the populations to become progressively smaller, have fewer and smaller eggs with lower survival and growth, and have lower foraging and feeding rates, the researchers report.
The figure shows the decrease in body size in Atlantic silverside as found by a research team led by UCR graduate student Matthew Walsh. The silverside, having been reared for five generations in laboratory experiments, are all the same age. The fish shown here are from the fifth generation. The fish on the left are from populations from which large individuals were harvested over five generations; the fish in the middle are from populations from which fish were harvested at random over five generations; and the fish on the right are from populations from which only small fish were harvested over five generations. (Photo credit: M. Walsh)