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Exploring Alternatives
Still, for California drift netters, who often fish 200 miles offshore, installing pingers at sea can be perilous and time-consuming. The hand-sized orange canisters are attached to a line on the net, one pinger for every 300 feet of net.
"It takes about an hour to put them on and another hour to take them off," West said, "and it can be Victory at Sea out there. Sometimes it's just hellacious weather."
More practical solutions, however, are probably near. With larger pingers, fishermen might have to install only two or three per net.
American fishermen are now seeking government help in bringing pingers to fishing boats in Mexico, to save endangered porpoises in the Gulf of California known as vaquita.
Despite the bicoastal success stories, fishermen and government regulators must be cautious in how and where pingers are deployed. They probably won't work for every fishery or for every species of marine mammal, so each area must be studied first.
"All marine mammals do not hear the same," said oceanographer Potter. "They are as diverse as mammals on land. Comparing a right whale to a porpoise is like comparing a cow to a dog."
Cliff Goudy, director of the Center for Fisheries Engineering at the Massachusetts Institute of Technology, remains skeptical about how well pingers will work in some fisheries.
One technique that may work better, he said, is to warn fishermen about the marine animals - instead of the other way around. Goudy is testing acoustics to locate right whales during spring migration. Then, like flight control warnings to airplane pilots, fishermen could be warned to stay out of their path.
Because no fishing gear is perfectly selective, diners must accept the deaths of dolphins, whales and seals if they want to enjoy a meal of fresh fish, both fishermen and scientists say.
"We've never said the pinger is the panacea for the by-catch issue. It's just another tool," Kraus said. "There will always be animals that make mistakes. We will never eliminate by-catch altogether unless we eliminate fishing."
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