Read this passage about global fishing. Global consumption of large fish has led to an exploitation of fish populations. Overfishing has led to a decline in the populations of many species of large fish including North East Arctic Cod. The graph below shows the decline in the cod population.

A graph entitled North East Arctic Cod Population has year on the horizontal axis and estimated total biomass on the vertical axis. The estimated total decreases as time passes.

As the human population grows and countries continue to develop, the demand for large fish has been steadily increasing. Unfortunately, the average size of the cod has decreased because the fishing nets were designed to catch the large fish and the smaller individuals could escape more easily.

What is most likely happening to the genetic variation of the population of North East Arctic Cod?
The genetic variation in the population is increasing due to selective pressure.
The genetic variation in the population is decreasing due to selective pressure.
The genetic variation in the population is increasing due to gene flow.
The genetic variation in the population is decreasing due to gene flow.