Bycatch is a dangerous practice that has led to a decrease in marine biodiversity. Bycatch is the unintentional catch of any marine wildlife by fisheries. If a fishing boat went out to catch Tuna but caught several sharks, the sharks would be considered bycatch. For this reason, bycatch is almost always tossed overboard as waste. Most marine creatures do not survive this process. Each year, 300,000 small whales and dolphins are killed due to bycatch. Hundreds of thousands of fish, turtles, and seabirds are killed due to this gruesome practice. Bycatch is the biggest threat to the survival of many marine species.
https://www.fishforward.eu/en/project/by-catch/