PORTSMOUTH, N.H. — A device designed to warn harbor porpoises and other marine mammals to steer clear of gillnets has proved effective during a two-month experiment, test sponsors say.
The device, known as a pinger, emits a gentle but insistent beep audible to the sea animals. Project participants believe porpoises respond to the beep by veering away from the gillnets, which can rise 12 feet from the ocean floor and may stretch for thousands of feet.
“If it can be sanctioned to do what it’s supposed to do here, its use can only be expanded,” said Erik Anderson, president of the New Hampshire Commercial Fishermen’s Association.
According to John Williamson, a fisherman from Kennebunk, Maine, who was field manager of the project, two porpoises died entangled in nets that were outfitted with pingers during the experiment that ended last week. In comparison, nets without active pingers snared 26 porpoises.
“These are not blasting sounds in the water to drive them out of there,” says John Lien of Memorial University in Newfoundland, a professor of animal behavior who developed the pinger. “It simply calls attention: `Hey, these things are here.”‘
It is uncertain how many porpoises are snagged by gillnet fishermen in Maine, New Hampshire and Massachusetts, but the issue has generated increased concern.
Porpoises travel the East Coast and at least one estimate pegs the number killed by gillnets annually at 1,000 or more.
“As an industry, our goal is to draw up our take-down to zero,” said Terry Stockwell, a fisherman from West Southport, Maine, who participated in the experiment. “I personally don’t like to see any fish or animal taken that can’t be sold.”
For the first time this year, the New England Fishery Management Council barred gillnet fishing in Maine, New Hampshire and Massachusetts during the fall porpoise migration, exempting only those participating in the experiment.
Williamson said project data still must be analyzed. But already, Scott Kraus of the New England Aquarium in Boston, the principal investigator for the Gulf of Maine Harbor Porpoise Project, says he is optimistic that the experiment will stand up to scientific scrutiny.
“I feel very optimistic about the statistical significance of this work,” he said.
The federal government funded the $530,000 study, and Kraus said scientists will report their findings in March or April.
Pat Fiorelli, a spokeswoman for the fishery management council, said gillnetting restrictions conceivably could be eased if pingers are proven effective.
Stockwell said the battery-operated pinger, which is also in use by Canadian fishermen and being tested in Australia, does not appear to reduce a fisherman’s harvest.
“It has seemingly no effect on our catch,” he said.