The price for your favorite seafood dish might be much higher than the amount listed on the menu. A new study says US fishing practices are responsible for the deaths of tons of sea turtles, dolphins, and whales.

United States ocean conservation group Oceana released a new study that pointed to nine fisheries in the USA responsible for billions of pounds of bycatch every year. Bycatch is the name for the amount of non-targeted marine life caught while fishing, says the report, entitled Wasted Catch: Unsolved Problems in U.S. Fisheries. The nine worst fisheries are responsible for nearly half of the world-wide bycatch each year, with some fisheries throwing out over 60% of what they catch. According to Oceana, bycatch is the leading threat to ocean life and the cause of dangerous overfishing.

Dominique Cano-Stocco, campaign director for Oceana, talked to The Daily Beast about the report, saying, “We’re allowing the capture and death of whales, dolphins, porpoises, turtles, and more." Cano-Stocco claims that the problem is the giant nets and rakes fisheries use to capture their targeted fish, which drag along the ocean floor and disrupt habitats, as well as catching a large number of non-targeted fish. The report states that 300 whales and 700 sea turtles were bycatch casualties in the Gulf of Mexico in a single year. “If we don’t clean up these particular fishing gears then we’re continuing to throw away millions of pounds of fish every year as waste. It’s absurd,” she says.