The text on this site is presented as an archival version of the script of "Ocean Planet," a 1995 Smithsonian Institution traveling exhibition. The content reflects the state of knowledge at the time of the exhibition, and has not been updated.

Nets are not always selective: some scoop up everything in their paths--the target catch, as well as many non-target species (the by-catch). Unwanted or undersized animals culled from a catch are discarded--thrown back into the sea, dead or dying.

A shrimping crew culls the by-catch, Gulf of Mexico Commercial marine fisheries in the U.S. alone toss away up to 20 billion pounds of by-catch each year--twice the commercial and recreational catch combined §.
photo © Robert W. Parvin

Sorting catch and by-catch on a shrimpboat deck, Georgia, 1986 Shrimpers tow nets that collect shrimp, and many other animals in their path. Red snapper, croaker, mackerel, sea trout, spot, drum, and other fishes--up to nine times more than the shrimp catch--are dumped overboard, already dead or dying §.
photo © John Domont, Center for Marine Conservation

Dead by-catch from shrimp trawlers, Texas coast, Gulf of Mexico, 1993
photo © Bob Cranston


Driftnets drowned by-catch

With nearly invisible filament mesh, enormous driftnets (used in the open ocean) catch and hold fish by the gills. Driftnets also entangle and drown birds, sharks, whales, and dolphins. The by- catch problem was so dire that the United Nations banned large- scale driftnetting on the high seas in 1993, prompted by widespread protest from governments and conservation groups around the world § §. Smaller driftnets are still being used in coastal waters, including those of the U.S.

Driftnetting in the North Pacific, August 1990 When strung together, driftnets could sweep almost 40 miles (60 km).
photo © Lorett Dorreboom/Greenpeace

Drowned white-sided dolphin, North Pacific, 1990 During the peak years of driftnetting in the late 1980s, more than ten thousand dolphins and whales and millions of sharks were killed annually §.
photo © Roger Grace/Greenpeace

3-mile-long Japanese driftnet displayed on the National Mall, Washington, DC, October 1990
photo © Robert Visser/Greenpeace

Safety Caps

TEDs let sea turtles take the easy way out

A sea turtle, trapped in a shrimp net and unable to surface for air, can drown in 40 minutes. But since May 1990, many U.S. shrimp trawls in the Atlantic and Gulf of Mexico have been required to use turtle excluder devices--TEDs §. Many Central American countries now also require TEDs in the Gulf, Caribbean, and western Atlantic §. TEDs reduce shrimping- related sea turtle mortality by about 97 percent §.

TED (turtle excluder device)
Sea turtles hit a grid before entering the main part of the net. Shrimp slip through the grid into the net, but turtles slide along the bars and out a webbed flap §.
Illustration © Bonnie Branner

Nordmore grate gives finfish a break

Named for the Norway county where it was developed, the Nordmore grate was designed to eliminate by-catch of small fish in shrimp nets. Since 1992, American shrimpers in the Gulf of Maine have used the grate to protect stocks of haddock, cod, and flounder §.

Nordmore grate Mesh funnels shrimp and fish to the bottom of the net. Shrimp go through the grate; almost all fish escape through an opening in the net above the grate § §.
Illustration © Bonnie Branner

More Information:

Ocean Planet Exhibition Floorplan

gene carl feldman ( (301) 286-9428
Judith Gradwohl, Smithsonian Institution (Curator/Ocean Planet)