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October 17, 2007- Scallopers help recover turtle transmitter (Fairhaven, MA) by James Casey, Amanda Southwood and Molly Lutcavage
The side benefit of cooperative research – improved communication between fishermen and scientists – recently came into play when a Fairhaven scalloper crew dredged up a piece of research gear and recognized its importance.
What happened next turned out to have the makings of a good detective story. So let's start at the beginning.
James Casey, a graduate student working with Amanda Southwood in the Department of Biology and Marine Biology at the University of North Carolina Wilmington, studies the feeding behavior and foraging habitat of leatherback turtles.
As part of his thesis research, Casey deployed satellite transmitters and stomach temperature pills on nine leatherbacks nesting on Sandy Point National Wildlife Refuge on St. Croix in the US Virgin Islands.
The goal of Casey's study, which was funded by the Large Pelagics Research Center of the University of New Hampshire (UNH), was to monitor diving patterns, stomach temperature, and feeding behavior of leatherbacks during the period at sea between nesting events.
Turtle Number 5, better known to Casey and his field crew as “Grace,” was laying her fifth clutch of the season on the night of May 23, 2007 when the research team attached a satellite transmitter to her enormous leathery back, which measured 64.8", and fed her a stomach temperature pill.
Casey anticipated Grace would return to the same location to lay a sixth clutch of eggs within seven to 10 days. This return would provide an opportunity to retrieve the transmitter and download archival data on diving and feeding behavior during the internesting interval.
But the turtle did not return. Argos satellite locations obtained from tag transmissions indicated that, after leaving St. Croix, Grace remained in Caribbean waters for 13 days before embarking on a post-nesting migration, taking her satellite transmitter with her.
But what was initially viewed as a disappointment – losing the transmitter and the precious information stored on it – became something of a miracle.
Signal lost, found
Grace was tracked for 60 days, traveling more than 1,860 miles from St. Croix to the waters off Long Island, NY. Then the satellite tag ceased transmitting on July 23 approximately 40 miles off Long Island.
The abrupt failure of satellite transmissions could have been the result of multiple complications, but researchers thought it was most likely that the transmitter fell off the turtle and sank to the ocean's floor.
Astonishingly, after 86 days of inactivity, the transmitter began sending signals to Argos satellites again on Oct. 17, an indication that it had resurfaced.
Initial October Argos locations were within 3.1 to 3.7 miles of the July 23 locations. This information, coupled with data that indicated the transmitter was moving at speeds faster than the average rate of travel for a leatherback, led Casey and Southwood to believe that the transmitter had somehow been dredged from the ocean floor, and was onboard a fishing vessel. On Oct. 28, satellite transmissions indicated the transmitter had been brought ashore near New Bedford.
The next morning Casey contacted Large Pelagics Research Center collaborators Molly Lutcavage and Kara Dodge in Massachusetts with news of the transmitter's reappearance. Their first impression was that the transmitter was reporting from well-known scallop grounds.
Following the trail
It took just one phone call to tuna spotter pilot George Purmont of Little Compton, RI to get the search underway. Purmont's links to the UNH Large Pelagics Lab were forged during 14 years of cooperative research on bluefin tuna, and he'd recently helped locate leatherback turtles for Kara Dodge's tagging study off Cape Cod.
Purmont spots for tuna purse seiners who fish for scallops after tuna season closes, and he was soon on his way to Fairhaven to consult with the crews.
With the most recent location coordinates reported by Argos, Lutcavage and Casey used Google Earth to narrow the search to a location right off Route 6 in East Fairhaven, MA, and Purmont headed there as their onsite detective.
Purmont searched East Fairhaven for signs of a fisherman's home or business that corresponded with the location information, but with no luck. He then drove across town to check with fish plant managers, and learned that a few scallop boats had landed at the dock at the time the satellite transmitter began to report from land.
The researchers were prepared to wait for the fish plant manager to question the captains, but Purmont wanted to give it one more try. On instinct, he headed back to East Fairhaven and spotted a fisherman's truck he hadn't noticed before.
Recovery
Answering the knock at her door, Mrs. Joseph Correia told Purmont that yes, indeed, her husband was a scallop fisherman. Within minutes, Purmont put Lutcavage on his cell phone with Joe Correia, captain of the Kayla Rose, whose vessel had scooped up the satellite tag from the ocean floor.
Correia had given the transmitter to his brother-in-law to deliver to the Woods Hole Oceanographic Institution. Having previously worked with Virginia Institute of Marine Science researchers to test turtle excluder chains for scallop dredges, Correia knew that the transmitter would be important to researchers.
The turtle team is deeply indebted to “detective” George Purmont for his generosity and help in locating the transmitter, and to Joe Correia, who refused any reward for its return, preferring the money be “put toward turtle research.”
With a great ground team and Google Earth, it took less than a morning to recover this critical transmitter. Casey is currently analyzing the valuable data downloaded from the still-functional tag and will incorporate these unique data into his master's thesis.
