Question

Starting in 1945, nets designed to catch the biggest salmon were used in the Pacific Northwest. As a result, the smaller salmon had an advantage and had a better chance of survival. The small salmon survived to pass on their genes to succeeding generations.

Which type of natural selection is at work here?

directional selection

disruptive selection

stabilizing selection

Answer 1

Directional selection.

The fishing nets selectively removed the largest salmon, giving a survival/reproductive advantage to the smaller extreme. That shifts the population mean toward smaller size (not favoring intermediates or both extremes).