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Porpoise Bycatch Prevented with Proper Pinger Use
The correct-use of acoustic warning systems on fishing gear in the Northeast has become increasingly important to counter the recent rise in bycatch of harbor porpoises, one of the region’s most vulnerable marine mammals.
In a proactive effort to reduce bycatch-- the technical term for the fish, marine mammals, sea turtles, and seabirds caught unintentionally-- NOAA Fisheries is working with fisherman to ensure the proper use of “pinger” technology. According to NOAA research, if used correctly, this preventative technology is 90 percent effective in reducing entanglements by warning harbor porpoises away from fishing nets.
Pingers are small acoustic devices Northeastern fishermen are required to attach to their gillnets to reduce marine mammal bycatch during specific fishing seasons. When a gillnet is submerged underwater, the pingers attached to the net broadcast short, high pitched sounds or “pings” every four seconds. Those pings are designed to deter harbor porpoises from getting close to the net.
A gillnet is a series of nets that are strung together to form a wall of net. Fish are caught by hitting this wall and “gilling” themselves in the mesh. Most of the time, the targeted fish are the ones caught in the gillnets. However, marine life, such as harbor porpoises, may also accidently get entangled in the nets– a situation that the proper number of pingers is often able to prevent.
Right now, NOAA Fisheries equipment specialists like John Higgins, are working to train NOAA enforcement officers, state officers, and the Coast Guard to ensure they can help fishermen learn to use these detectors correctly. In addition, NOAA staff hold one-on-one training sessions with fisherman that teach how and when to use pingers; how to check if they are not working; and where pingers can be purchased.
“There is a lot of satisfaction in the results of proper pinger use,” said Higgins. “What we need to do is make sure there is 100 percent compliance.”
The number of pingers required by NOAA depends on the length of fishing nets. According to the Harbor Porpoise Take Reduction Plan every net within a string needs to have a working pinger on each end. Studies have shown that when there are too few pingers, or if a device is not working, bycatch often increases.
“Not having the right number of pingers may actually be worse than having none at all,” said Northeast Marine Mammal Team Coordinator, David Gouveia. “Scientists believe that porpoises, in an attempt to avoid a lone pinger, end up swimming straight into another area in the string of nets.”
Between 1998 and 2003, when pingers were first required, porpoise bycatch numbers declined to approximately 300 animals per year, down from 1,800 prior to the requirements. But, entanglements are on the rise, driving the new emphasis on the use of pinger technology by NOAA Fisheries.
“NOAA Fisheries trainers ensure fisherman know the correct amount of pingers and how to check if the pingers are working properly,” said Higgins. “This is the key to preventing harbor porpoise bycatch.”
For more information about this story, please contact Maggie Mooney-Seus at Marjorie.Mooney-Seus@noaa.gov.
Written by Hallie Sacks
Contributors: Maggie Mooney-Seus, Justin Hanacek and Matthew Ellis