Population dynamics of fisheries is a way for people to make sure that the number of fish in the ocean stays the same. This is important because if too many fish are taken away, then there won't be enough left to catch and eat. Population dynamics helps people make sure that the amount of fish in the ocean stays the same by counting how many fish there are, how many fish are taken away each year, and how many fish reproduce each year. This way, people can see if they should be taking away more or fewer fish. They can also see if they should be putting more fish back in the ocean to make sure that enough fish survive and reproduce.