Question

Overfishing of salmon has caused populations of wild salmon to decline. To combat this decline, salmon are raised in hatcheries, and then released to the wild. However, researchers have found that hatchery-raised salmon have reduced reproductive success in the wild, compared to wild salmon. They have also identified many genetic differences between hatchery-raised and wild salmon. Which statement describes the most likely reason for the differences between hatchery-raised and wild salmon? A. The pressures of a hatchery environment and of the wild environment select for different traits. B. Hatchery-raised salmon have evolved to have completely different genomes from those of wild salmon. C. Hatchery-raised salmon develop into stronger swimmers than those raised in the wild. D. The pressures of a hatchery environment promote convergent evolution between hatchery-raised and wild salmon.

Answer 1

B. Hatchery-raised salmon have evolved to have completely different genomes from those of wild salmon.

Rivers and streams of the Paci­fic Northwest used to be so full of wild salmon so fishermen like to say it could cross the waterways on the fish's backs. When salmon were the only means of crossing the rivers and fishermen would be out of luck today.