Ocean conversation group Oceana has named nine “dirty” fisheries that, combined, throw away more than half of what they catch and are responsible for more than half of US bycatch. Bycatch is wasted edible fish and drowned animals that are thrown back into the sea. In the image, dead turtles are caught in a net. (Photo : Projeto Tamar Brazil / Marine Photobank via Oceana )

Ocean conversation group Oceana has named nine "dirty" fisheries that, combined, throw away more than half of what they catch and are responsible for more than half of US bycatch. Bycatch is wasted edible fish and drowned animals that are thrown back into the sea.

"Anything can be bycatch," Dominique Cano-Stocco, campaign director at Oceana, said in a statement. "Whether it's the thousands of sea turtles that are caught to bring you shrimp or the millions of pounds of cod and halibut that are thrown overboard after fishermen have reached their quota, bycatch is a waste of our ocean's resources. Bycatch also represents a real economic loss when one fisherman trashes another fisherman's catch."

Oceana's report, "Wasted Catch: Unsolved Bycatch Problems in US Fisheries," reveals between 17-22 percent of US catch is discarded every year. US bycatch could amount to up to 2 billion pounds every year.

The group said that some fisheries discard more fish at sea than they bring to port and that adequate monitoring of fishing operations' discarding practices is not in place.

"One in 100 fishing trips carry impartial observers to document catch, while many are not monitored at all, leading to large gaps in knowledge and poor quality data," Oceana reported.

The report lists the nine "dirty" fisheries as:

Southeast Snapper-Grouper Longline Fishery - Discarded 66 percent of catch, including more than 400,000 sharks in one year.

California Set Gillnet Fishery - Discarded 65 percent of catch as waste, including more than 30,000 sharks and rays as well as valuable fish over three years

Southeast Shrimp Trawl Fishery - Discarded 64 percent of catch. For every pound of shrimp landed, 1 pound of billfish is discarded; thousands of sea turtles are killed annually

California Drift Gillnet Fishery - Discarded 63 percent of catch. In five years, nearly 550 marine mammals were entangled or killed.

Gulf of Alaska Flatfish Trawl Fishery - Discarded 35 percent of catch. In one year, more than 34 million pounds of fish were thrown overboard, including 2 million pounds of halibut and 5 million pounds of cod

Northeast Bottom Trawl - Discarded 35 of catch. Each year, more than 50 million pounds of fish are thrown overboard.

Mid-Atlantic Bottom Trawl Fishery - Discarded 33 percent of catch. In one year, nearly 200 marine mammals and 350 sea turtles were captured or killed.

Atlantic Highly Migratory Species Longline Fishery - Discarded 23 percent of catch. In excess of three quarters of the wasted fish are valuable tuna, swordfish and other billfish.

New England and Mid-Atlantic Gillnet Fishery - Discarded 16 percent of catch, including more than 2,000 dolphins, porpoises and seals were in one year.

Click here to see a map of these fisheries.