Fish are considered a renewable resource. However, some scientists believe that Earth's oceans are running out of economically valuable fish. What is the most likely reason for this?
a. They are no longer reproducing.
b. They are being harvested faster than they can replenish themselves.
c. They are all being eaten by other predators in the oceans, such as sharks and whales.
d. They are migrating to other bodies of water.