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Shrimp trawl “excluder” cuts marine bycatch up to 40 percent

Shrimp trawlers are often regarded as the wrecking balls of the sea. Research has found that up to 90 percent of what they haul up from the seafloor is unwanted–and often unused–bycatch.

Conservation organizations like the World Wildlife Fund (WWF), governments and the fishing industry have been trying to find ways to reduce the bycatch. Here’s a progress report on one new invention:


French Guiana’s shrimp fishing fleet off the northern coast of South America has been directed to use devices such as the new Trash and Turtle Excluder Device (TTED), in the photo above, that reduces accidental capture of larger marine species by up to 40 percent. WWF will be discussing the new device at this this week’s Seafood Summit in Paris, France.

Photo by T. Nalovic/CRPMEM

A new law requiring shrimp fishers in the South American department of France to use devices that reduce unwanted fish catch will help better protect marine turtles and other vulnerable marine species in the region, WWF said in a news statement last night.

Widespread use of the new TTED, which took three years to develop, will greatly reduce bycatch among shrimp trawlers, WWF said. In French Guiana,

“Tropical shrimp fisheries represent a major source of undesired bycatch. Without a bycatch-reduction device in place, shrimp represents only 10 to 30 percent of the total catch, meaning the rest is made up of other marine species,” the Switzerland-based conservation charity said.

“At least 40 percent of what is taken from oceans by fishing activities is unmanaged or unused.”

Nearly half of the world’s recorded fish catch is unused, wasted or not accounted for, according to estimates in a scientific paper co-authored by WWF, published last year. The paper, Defining and Estimating Global Marine Fisheries Bycatch, calculated that each year at least 38 million tonnes of fish, constituting at least 40 percent of what is taken from oceans by fishing activities, is unmanaged or unused and should be considered bycatch.


Discarding unwanted species caught in shrimp nets has been a way of fishing for decades, as this 1957 photo made in the Gulf of Mexico shows. “Overfishing has been historically [the] oldest and [most] major threat to ocean life today,” says National Geographic fellow Enric Sala, in a National Geographic Web feature on Overfishing

NGS stock photo by Robert Sisson 

The TTED is an improvement of a previous device, the Turtle Excluder Device, that consists of a rigid grill inserted at a 45 degrees angle in the trawl with an opening toward the top or bottom, WWF said. The U.S. National Oceanic and Atmospheric Administration (NOAA) has documented a 97 percent reduction in marine turtle captures through using the previous device, and additional TED studies conducted internationally have shown a reduction in large marine organism bycatch of as much as 91 percent.

The latest version of the excluder combines the advantages of different systems and has been found to reduce all bycatch by 25 to 40 percent.

The device also has some practical advantages for the shrimp fishers. It reduces sorting time and risks of injury due to sharks and rays being caught, WWF said. “The new gear also improves the quality of shrimps, which are less likely to be crushed in the bottom of the trawl, and may also lead to a reduction in the amount of fuel consumed by the boats.”


NGS stock photo of pink shrimp by Robert Sisson

The TTED is the culmination of years of research. With funding provided by the European Union and the DIREN (Regional Environmental Authorities), WWF commissioned a study from IFREMER (French Research Institute for Exploitation of the Sea) to determine which selective gear was the most adapted to fishing conditions in French Guiana. The initial trials, conducted under experimental conditions, were carried out on board a shrimp trawler.

“Following this work, shrimp industry members expressed the need to continue these experiments and to become more involved in the project. In response, WWF and the French Guiana Regional Fishery and Ocean Farming Commission (CRPMEMG) began working in close collaboration in order to determine the best gear for the French Guiana fleet,” WWF said.

“With technical support from NOAA and IFREMER, the CRPMEMG carried out numerous at sea trials in close collaboration with French Guiana fleets. Specific parameters where tested such as the shape and spacing between the bars of the selective grid. These trials allowed the fleets and the crews onboard the shrimp trawlers to understand the advantages of a more selective fishing gear and the benefits of using it in French Guiana.

“Based on the results and the captains’ recommendations, the Commission decided to make the use of this TTED system mandatory by January 2010, when the annual fishing licences are issued.”

The TTED was developed by the CRPMEMG and fishermen with the assistance of IFREMER, NOAA, French Ministry of Agriculture and Fisheries, Région Guyane, the European Fund for Fisheries (FEP), and WWF.

You might also be interested in:

Global Fisheries Crisis (National Geographic Magazine)


  1. younes nourian
    July 30, 2013, 12:58 am

    I am a student of mechatronics and automatic counting machine, brine shrimp project I’m working on.
    To do this I am in need of short films shrimp larvae.
    Filmed during the breeding and rearing ponds’m ready to move.
    Please help me and a few short videos to send to me a minute larvae.
    Please help me in my life where I do not have any shrimp or larvae.

    Describe how the filming of the brine shrimp
    Therefore, to simulate the transmission channel and the steps we just filmed

    1- a channel or duct cables white plastic surface to a depth of 2 to 4 cm wide, 5 cm long and 1 meter can provide.

    2- channel or duct to the ground. Duct is a bit steep. Doubt as to the number of larvae with eyes, count to 200. Then along the top of the slope down pour water in the channel. It flows so smoothly., And the way the camera can film the docket kept constant. Videos about 60 seconds to prepare. And to store it. And file name, for example, going to work toward 200.

    3- between the camera and see the quality of the surface of a sample film is adjustable. (The video can also be counted by eye). After counting, if the eye is favorable.
    4- Steps 1 to 3, with samples of 300 and 400 each and 500 are repeated.

    5- To save the movie in PC movie is a clear example of a film is going to work toward fielm200 200 chunks.
    If possible take a few photos as well as movies to check more
    6- Y_nourian@Yahoo.com address to send videos and photos to

    Thank you

  2. chris henry
    south texas
    August 3, 2012, 5:41 pm

    wtf lol u really beleive this crap! im a shrimper myself we catch around 30pds a drag keep 20 and dont u know everything we dont keep is eaten by fish birds and dolphjns. pps ive talked to older shrimpers and they ALL told me they never caught a turtle unless it was already dead