Pop Goes the HARP

Deep ocean sound recorders on the deck of a research dhip

Eric Matzen among the HARPS. Photo by NOAA/NEFSC/Henry Milliken

This cruise aboard the NOAA Ship Henry Bigelow is dedicated to sea turtle ecology and oceanography, but we have also been successful replacing passive acoustic recording instruments called HARPs (High-frequency Acoustic Recording Packages), made by the University of California’s Scripps Institution of Oceanography.  These instruments have to be replaced annually, and we are entering our third year of data collection using them.

The HARPS sit on the edge of shelf-break canyons at about 1000 m deep. We have to be exact in our drop points or the units could descend to crushing depths in the canyons or land in shallow water near fishing activity.

We position the ship over the instrument, contact the acoustic release, and give the release command, which jettisons the ballast weights on the unit. It takes about 15 minutes for the HARP to float to the surface, so this is an exciting time waiting and watching. Everyone wants to be the first to spot the surfaced unit, but on the first recovery, Mate Dana Mancinelli spotted the HARP while it was still under water on its way up.  That is good spotting!

yellow recording device and orange floats bobbing on the surface ot he water

HARP floating at the surface having successfully jettisoned the ballast that’s kept it on the ocean bottom for the past year. Photo by NOAA/NEFSC/Leah Crowe

Large yellow recording being pulled onto resarch vessel

HARP coming aboard during last stage of retrieval operation. Photo by NOAA/NEFSC/Heather Haas

The three recorders we are replacing are part of an  array of eight such instruments covering waters from Northeast Georges Bank to Florida. This network is a combined effort of NOAA Fisheries’ Northeast and Southeast Fisheries Science Centers to understand biological activity along the U.S. continental shelf break before the planned seismic exploration starts off the United States’ Eastern Seaboard.  They are part of the US NorthEast Passive Acoustic Sensing Network. While deployed, the HARPS record sounds made by many species including baleen whales, sperm whales, beaked whales, and dolphins.

Eric Matzen, NEFSC Protected Species Branch

Annamaria Izzi, Integrated Statistics

Aboard the NOAA Ship Henry Bigelow

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