High-tech transmitters giving up secret lives of Hawaiian seals

Hawaiian monk seal Kermit snoozes on an Oahu beach, oblivious to the transmitter on his back that gathers data about his movements for NOAA researchers. Up to 14 other seals in Hawaii will be wearing similar transmitters. (Credit: Barbara Billand)

Navy pays for devices that also gauge how sonar affects species

Honolulu Advertiser, Sunday, April 11, 2010
Written by Diana Leone

Up to 15 monk seals in Hawai’i will be doing their part over the coming year to help scientists understand them better.

he critically endangered animals will wear small transmitters that reveal their movements, including how deep they dive, when they haul out on land and how far they roam.

Accumulating normal habits of the seals also will be used to gauge the effect Navy training exercises, including use of sonar, may have on the animals.

The Navy is footing the bill for the $4,500-each transmitters, NOAA scientists’ travel and veterinary costs associated with the project. The project is slated to last several years.

Currently five seals are wearing the transmitters — one on O’ahu and four on Moloka’i. Additional transmitters will be placed on 10 more seals on Kaua’i and O’ahu in coming months, said Charles Littnan, lead scientist for NOAA Fisheries’ Hawaiian Monk Seal Research Program.

The transmitters are slightly larger than a deck of cards with a short antenna and are glued to fur on a seal’s back, where it will least interfere with its daily life. Pregnant, nursing, sick or wounded seals, or seals near to their annual molt of their fur will not be tagged, Littnan said. Only seals of 200 pounds or more will be tagged.

The transmitters “are a lot like a smartphone,” Littnan said. They show a seal’s location with global positioning coordinates and also track water temperature, salinity and depth of dives. They “phone home” when the seals are on the surface of the water or on land and the devices can transmit via a cell phone tower, Littnan said.

So far, an O’ahu seal dubbed “Kermit” by seal protection volunteers has been the star of the project. Several tagged seals lost their transmitters, prompting a change in the glue used to attach them, and the Moloka’i seals have only recently been tagged.

Already, Littnan knows that Kermit travels regularly back and forth between Diamond Head and Nānākuli. Some of his favorite fishing grounds seem to be offshore from ‘Ewa Beach. The seal often spends 12 to 24 hours at a time swimming and diving in the ocean, then hauling out at a variety of beaches for a rest.

“Monk seals dive pretty much from the time they hit the water through their entire trip,” Littnan said. “Depth varies, but duration of each dive is usually around six minutes, and surface times usually about one or two minutes. They feed almost entirely along the bottom, which is why the dives are so flat.”

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