Global catch from bottom trawling has been estimated at over 30 million tonnes per year, an amount larger than any other fishing method. Concerns about the environmental impacts of bottom trawling have led to changes in gear design, such as the addition of turtle excluder devices to reduce bycatch, and limitations on locations where bottom trawling is allowed, such as marine protected areas. Moreover, a 2021 paper estimate that bottom trawling contributed between 600-1500 million tons CO2 a year of carbon emissions by disturbing CO2 in the sea floor-- or about as much as emissions as Germany, or as much emissions as aviation. International attempts to limit bottom trawling have been ineffective.