Fish populations around the globe are in serious trouble, thanks to the modern fishing industry. Instead of simply using poles and intuition, factory ships employ radar, sonar, helicopters, and even spotter planes to hunt down schools of fish, which they catch using massive nets and lines studded with hundreds of hooks. These technologies allow us to snare all kinds of deep-water delicacies—but they come with an ecological cost, according to TED-Ed’s video below.

Learn how overfishing harms the environment—and what we can do to protect our oceans—by listening to marine biologist Ayana Elizabeth Johnson and environmental studies scholar Jennifer Jacquet’s lesson below.