Bottom trawling is one of the most destructive ways to catch fish, and is responsible for up to half of all discarded fish and marine life worldwide. Valuable fish, turtles, seabirds, marine mammals and other animals are all captured and discarded by bottom trawls, and many do not survive . In a side-by-side comparison, bottom trawling for spot prawns threw away nine times as much bycatch as more selective fishing gear. Unwanted fish caught in bottom trawl. R. Visser, Greenpeace. Fish dumped by trawlers in Belize attract pelicans. In the Gulf of Mexico, scientists estimate that for every pound of shrimp caught, between four and ten pounds of marine resources are thrown away. Shrimp trawling in the Caribbean and Central America also has high discard rates, with shrimp trawls in Panama discarding more than 80% of their catch. Even small-scale fisheries catch high percentages of unwanted fish and marine resources when using bottom trawls, including Brazil as well as Trinidad and Tobago. In 2007, shrimp trawlers in Belize landed only 19 metric tons of shrimp and likely discarded about 76 to 190 metric tons of other marine life. The fish thrown away by bottom trawlers in Belize are probably a third of total spiny lobster landings for the same year.

Local fishermen catch fewer fish for the same effort when competing with bottom trawls. In Indonesia, local fishermen’s catches declined 40% after bottom trawling expanded. Bottom trawls also conflict with the operation of other kinds of fishing gear, leading to disputes with dead fish discarded by a bottom trawler. Industrial trawlers operated by foreign fleets drag through the gear of local fishermen in Guinea, destroying wooden canoes, other gear, and causing personal injuries.

This also has a great impact on tourism.