“That’s $18,000 in pingers,” Dodge said, setting the heavy load of 160 of the plastic devices onto the floor. Pingers emit a high-frequency sound that harbor porpoises in particular do not like. Gillnet fishermen attach these devices, about the size of a closed fist, to the rope of the nets they suspend vertically in the water from buoys, like sheets on a clothesline, to catch fish. Each fisherman can set out 100 or more of these large nets that sometimes stay out for days.
The hope is that the signal of the pingers will discourage harbor porpoises — small 5-foot-long mammals protected under the Marine Mammal Protection Act — that eat herring, capelin and other schooling fish, from swimming into the nets and becoming entangled.
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