Question

Many states in the United States have fishing regulations that allow fishermen to keep only fish that are above a certain size. Smaller fish that are caught must be thrown back into the water. While these laws were originally designed to protect fish populations, the evolutionary effects of these actions are causing harm. Which of these statements explains how such regulations will most likely affect the fish populations where they are enforced?


Fish size, genetic diversity, and species diversity will increase.


Fish size, genetic diversity, and species diversity will decrease.


Fish size will decrease, but genetic diversity and species diversity will increase.


Fish size will increase, but genetic diversity and species diversity will decrease.

Answer 1

The correct statement is:

**Fish size will decrease, but genetic diversity and species diversity will increase.**

This phenomenon occurs because fishing regulations that only allow the keeping of larger fish can lead to a scenario where smaller fish are selectively favored. Over time, this can result in a population of fish that are generally smaller in size because the larger individuals are removed before they can reproduce. This selective pressure can lead to a decrease in average fish size over generations.

Moreover, as smaller fish are increasingly favored and survive to reproduce, there may be an increase in genetic variation since those smaller individuals may come from a wider range of genetic backgrounds compared to the larger fish that are being caught. However, species diversity can be more complex to assess, as it may depend on other ecological factors, but in general, the removal of larger fish can open up niches for smaller fish and other species, potentially leading to increased species diversity.

Thus, while the average size of fish in the population is likely to decrease, the overall genetic and species diversity may see an increase due to changes in reproductive dynamics and ecological niches.