"Seaspiracy" sheds light on the dark world of commercial fishing, revealing the hidden truths behind the industry. The film exposes the devastating impact of fishing on marine life, including overfishing, bycatch, and the destruction of ocean ecosystems. It challenges the notion of sustainable fishing and highlights how the oceans are in major deficit due to human activity.

The documentary emphasizes that fishing is not just about harming fish, but also about endangering other marine species like whales, dolphins, seabirds, and sea turtles. It points out that plastic pollution is not the biggest threat to the oceans, but rather the industrial fishing practices that are often overlooked. "Seaspiracy" concludes by urging viewers to stop eating seafood as the best way to protect the oceans and marine life.