What does overfishing mean?

Overfishing refers to the practice of catching fish at a rate that exceeds their ability to reproduce and replenish their populations. This means that when fish are removed from the water faster than they can naturally grow back, it leads to a depletion of fish stocks, which can have significant ecological and economic consequences.

The other options don't accurately capture the essence of overfishing. For instance, an increase of fish in an area does not relate to the concept of overfishing, as it implies a healthy ecosystem with sustainable fish populations. Similarly, the removal of fish at a sustainable rate suggests conservation and balance, which is the opposite of overfishing. Finally, the introduction of fish species into new areas is referred to as species introduction or translocation, and it does not relate to the concept of fishing rates at all. The correct answer clearly defines overfishing as a critical issue concerning the sustainability of fish populations in marine environments.