Satellite tracking of migrating loggerhead sea turtles (Caretta caretta) displaced in the open sea

Luschi, Paolo; Hughes, George R.; Mencacci, Resi; Bernardi, Elisabetta De; Sale, Alessandro; Broker, R.; Bouwer, M.; Papi, Floriano

doi:10.1007/s00227-003-1117-5

Cited by 33 publications

(33 citation statements)

References 20 publications

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“…There is no geographic difference in expected carapace size among the Brazilian loggerhead nesting populations (Marcovaldi & Laurent 1996, Baptistotte et al 2003 and neither is there any expected size difference between these and other Atlantic loggerhead nesting populations (Tiwari & Bjorndal 2000). However, Atlantic nesting loggerheads are on average much larger than loggerheads nesting in the Mediterranean (Margaritoulis et al 2003) or the Pacific (Hatase et al 2002, Limpus & Limpus 2003 and Indian Oceans (Luschi et al 2003). Whether the larger expected size of loggerheads nesting in the Atlantic results in higher size-dependent reproductive output (shorter nesting season interval, larger clutch size, higher seasonal clutch frequency) is yet to be determined but warrants further investigation.…”

Section: Discussionmentioning

confidence: 99%

Conservation status of the loggerhead sea turtle in Brazil: an encouraging outlook

Marcovaldi¹,

Chaloupka²

2007

Endang. Species Res.

120

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The loggerhead turtle Caretta caretta is one of the large and long-lived species that comprise the charismatic marine megafauna. The loggerhead is considered endangered, especially in the Pacific Ocean, where there have been substantial declines in all the major nesting populations. On the other hand, some loggerhead nesting populations in the northwest Atlantic are apparently increasing, but the conservation status of loggerheads in the Atlantic-Mediterranean is not well known. Here we report on a long-term and geographically extensive study of the nesting abundance of the Brazilian loggerhead genetic stock resident in south Atlantic waters. We show that there has been a substantial long-term increase in nesting abundance of this once depleted Atlantic stock following the cessation of egg and turtle harvesting in the 1980s. We estimated that the 2003/2004 austral summer nesting season in Brazil encompassed more than 4800 loggerhead nests or >1200 nesters or > 0.57 million eggs. National conservation efforts have contributed significantly to the improving status of the Brazilian loggerhead stock since the mid-1980s, but there are emerging threats such as incidental capture in coastal and pelagic fisheries that might limit any further recovery. Moreover, we found that the Brazilian nesting population is probably one of the largest remaining loggerhead nesting populations in the world. Hence, continued protection of the Brazilian loggerhead stock is of paramount importance for the global conservation of this species.

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Section: Discussionmentioning

confidence: 99%

Conservation status of the loggerhead sea turtle in Brazil: an encouraging outlook

Marcovaldi¹,

Chaloupka²

2007

Endang. Species Res.

120

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“…They are also consistent with several published anecdotes in which marked turtles displaced from Nicaragua to Florida (Carr, 1956), from Nicaragua to the Cayman Islands (Carr, 1956), and from Ascension Island to the English Channel (Cornelius, 1865) also returned to their original capture sites. Not all turtle displacements have resulted in clear homing behavior (Luschi et al, 2001(Luschi et al, , 2003. In general, however, studies in which little or no homing has been reported have involved unusually long displacements, displacement of nesting turtles during the internesting interval when turtles are normally inactive, or placement of satellite transmitters directly on the turtles' heads (Luschi et al, 2001).…”

Section: Homing In the Oceanmentioning

confidence: 99%

Navigation and seasonal migratory orientation in juvenile sea turtles

Avens

Lohmann

2004

Journal of Experimental Biology

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Juvenile loggerhead and green turtles that inhabit inshore waters of North Carolina, USA undertake long seasonal migrations, after which they often return to specific feeding areas. In addition, juvenile turtles are capable of homing to specific sites after being displaced. As a first step towards investigating the navigational mechanisms that underlie these movements, juvenile turtles were captured in coastal waters of North Carolina and displaced 30-167·km along circuitous routes while deprived of visual cues. At the testing location, turtles were tethered in a circular arena and permitted to swim while their orientation was monitored. Between May and September, when juvenile loggerhead and green turtles inhabit feeding areas along the North Carolina coast, turtles oriented in directions that corresponded closely with the most direct route back to their capture locations. During October and November, however, both loggerhead and green turtles oriented southward, a direction consistent with the migratory paths of turtles beginning their autumn migration. The results demonstrate for the first time that both homing and migratory orientation can be elicited in juvenile turtles under laboratory conditions in which orientation cues can be readily manipulated. In addition, the results provide evidence that juvenile loggerheads can assess their position relative to a goal using local cues available at the test site and are therefore capable of map-based navigation.

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“…Telemetry studies typically group turtles into benthic or pelagic foragers based on the dive behavior and location (Hatase et al, 2002;Luschi et al, 2003;Hawkes et al, 2006). However, here we identified turtles exhibiting both behaviors of active pelagic foraging followed by dives to the benthic environment.…”

Section: Discussionmentioning

confidence: 82%

Videography Reveals In-Water Behavior of Loggerhead Turtles (Caretta caretta) at a Foraging Ground

et al. 2016

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Assessing sea turtle behavior at the foraging grounds has been primarily limited to the interpretation of remotely-sensed data. As a result, there is a general lack of detailed understanding regarding the habitat use of sea turtles during a phase that accounts for a majority of their lives. Thus, this study aimed to fill these data gaps by providing detailed information about the feeding habits, prey availability, buoyancy control, and water column usage by 73 loggerhead turtles across 45.7 h of video footage obtained from a remotely operated vehicle (ROV) from, 2008 to 2014. We developed an ethogram to account for 27 potential environmental and behavioral parameters. Turtles were filmed through the entire water column and we quantified the frequency of behaviors such as flipper beats, breaths, defecations, feedings and reactions to the ROV. We used the ROV's depth sensor and visible cues (i.e., water surface or benthic zone in view) to distinguish depth zones and assess the turtles' use of the water column. We also quantified interactions with sympatric biota, including potential gelatinous and non-gelatinous prey species, fish (including sharks), marine mammals and other sea turtles. We discovered that turtles tended to remain within the near surface and surface zones of the water column through the majority of the footage. During benthic dives, turtles consistently exhibited negative buoyancy and some turtles exhibited a dichotomous foraging behavior, first foraging within the water column, then diving to the benthic environment. Videography allowed us to combine behavioral observations and habitat features that cannot be captured by traditional telemetry methods, resulting in a broader understanding of loggerheads' ecological role in the U.S. Mid-Atlantic.

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Satellite tracking of migrating loggerhead sea turtles (Caretta caretta) displaced in the open sea

Cited by 33 publications

References 20 publications

Conservation status of the loggerhead sea turtle in Brazil: an encouraging outlook

Conservation status of the loggerhead sea turtle in Brazil: an encouraging outlook

Navigation and seasonal migratory orientation in juvenile sea turtles

Videography Reveals In-Water Behavior of Loggerhead Turtles (Caretta caretta) at a Foraging Ground

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