The first ‘lost year’ of Mediterranean sea turtles: dispersal patterns indicate subregional management units for conservation

Casale, Paolo; Mariani, Patrizio

doi:10.3354/meps10640

Cited by 52 publications

(59 citation statements)

References 48 publications

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“…As with loggerheads, information on the distribution of small turtles is particularly deficient, but in green turtles this applies to larger juveniles as well, given that no tracking experiment has been ever undertaken. Hatchling dispersal simulations indicated that green turtle hatchlings are mainly retained in the Levantine basin, where the nesting sites are (Casale & Mariani 2014). A high proportion of green turtles smaller than 30 cm CCL was reported to occur in southern Turkey waters ) while low numbers of small turtles < 40 cm CCL frequent the Adriatic (Lazar et al 2004), especially in the southern part, the Ionian and even the Tyrrhenian seas around Italy (Bentivegna et al 2011).…”

Section: Green Turtlesmentioning

confidence: 99%

“…extension of shallow areas offering suitable neritic foraging sites is in the northern Adriatic and the Libyan/Tunisian shelf, these represent key areas for both Mediterranean green and loggerhead turtles, given that both areas are frequented by adults and juveniles. Other factors may, however, play a role in determining the movement patterns observed: for instance, recent evidence suggests that the foraging locations of adult turtles might be influenced by their drift scenarios as hatchlings Scott et al in press), and this would explain, for example, why few adults forage in the western part of Mediterranean, given that rookeries are confined to the Eastern basin (see also Casale & Mariani 2014). Mediterranean adult loggerheads do, however, exhibit some variety in their movements, with some turtles foraging in offshore oceanic waters for at least part of their inter-reproductive phase, sometimes keeping on the move without fixing to any specific site (Zbinden et al 2008;Luschi et al 2013;Schofield et al 2013).…”

Section: General Considerationsmentioning

confidence: 99%

“…In the Mediterranean, recent simulations of hatchling dispersal have indicated that hatchlings from the Levantine and central nesting sites are mainly retained in the same areas of origin, while those from the Ionian region disperse widely to the Ionian, Adriatic and south-central Mediterranean areas Casale & Mariani 2014).…”

Section: Juvenile Loggerhead Turtlesmentioning

confidence: 99%

“…The loggerhead turtle is the most common species in the Mediterranean Sea, where it nests mainly in the eastern part, from which juveniles then disperse widely throughout the basin (Margaritoulis et al 2003;Casale & Margaritoulis 2010;Hays et al 2010a;Casale & Mariani 2014). The Mediterranean loggerhead population shows a genetic divergence from the Atlantic populations (Bowen & Karl 2007), and a population substructure (Laurent et al 1998;Carreras et al 2007;Clusa et al 2013), indicating the presence of independent management units for conservation.…”

Section: Introductionmentioning

confidence: 99%

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Movement patterns of marine turtles in the Mediterranean Sea: a review

Luschi

Casale

2014

Italian Journal of Zoology

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Understanding the at-sea spatial behaviour of sea turtles is a priority for their conservation. In the present paper, the current information on the distribution and movement patterns of the two species breeding in the Mediterranean, the loggerhead and the green turtle, is reviewed, focusing mainly on the 195 published routes of satellite-tracked turtles. A satisfactory level of knowledge about adults' migrations and other movements is reached only for loggerheads breeding at Zakynthos Island, Greece, and for green and loggerhead females nesting in Cyprus, while studies at foraging grounds are limited to loggerheads in the western and central parts of the basin. Adult males and females mostly show quite uniform post-breeding migratory patterns, typically moving towards individually specific neritic foraging grounds. A much higher variability is shown by loggerhead juveniles, which is probably associated with differences in their spatial behaviour while in oceanic or neritic waters. Evidence of seasonal migrations driven by lower temperatures in winter is available only for adult and juvenile loggerheads frequenting the two northernmost parts of the basin, i.e. the Ligurian and the northern Adriatic Sea. Current knowledge gaps and priorities for further research in the Mediterranean are discussed.

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Section: Green Turtlesmentioning

confidence: 99%

Section: General Considerationsmentioning

confidence: 99%

Section: Juvenile Loggerhead Turtlesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Movement patterns of marine turtles in the Mediterranean Sea: a review

Luschi

Casale

2014

Italian Journal of Zoology

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“…The trajectories of passively drifting particles are compared with those of observed turtles released from the same date and nesting location in the western North Pacific, thereby testing the passive migration hypothesis for juvenile loggerhead sea turtles in the North Pacific Ocean. Such insights will help assess the role of long-distance transport from currents and provide useful long-term information on small juveniles during a period where little is known [40]. This knowledge can also provide critical geographical information for conservation management strategies in areas that may host high concentrations of young individuals from this population.…”

Section: Introductionmentioning

confidence: 99%

Active dispersal in loggerhead sea turtles ( Caretta caretta ) during the ‘lost years’

et al. 2016

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Highly migratory marine species can travel long distances and across entire ocean basins to reach foraging and breeding grounds, yet gaps persist in our knowledge of oceanic dispersal and habitat use. This is especially true for sea turtles, whose complex life history and lengthy pelagic stage present unique conservation challenges. Few studies have explored how these young at-sea turtles navigate their environment, but advancements in satellite technology and numerical models have shown that active and passive movements are used in relation to open ocean features. Here, we provide the first study, to the best of our knowledge, to simultaneously combine a high-resolution physical forcing ocean circulation model with long-term multi-year tracking data of young, trans-oceanic North Pacific loggerhead sea turtles during their 'lost years' at sea. From 2010 to 2014, we compare simulated trajectories of passive transport with empirical data of 1-3 year old turtles released off Japan (29.7-37.5 straight carapace length cm). After several years, the at-sea distribution of simulated current-driven trajectories significantly differed from that of the observed turtle tracks. These results underscore current theories on active dispersal by young oceanic-stage sea turtles and give further weight to hypotheses of juvenile foraging strategies for this species. Such information can also provide critical geographical information for spatially explicit conservation approaches to this endangered population.

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Annual survival probabilities of juvenile loggerhead sea turtles indicate high anthropogenic impact on Mediterranean populations

Casale

Freggi

Furii

et al. 2014

Aquatic Conservation

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One of the major gaps in the knowledge of sea turtle population dynamics is survival probability, in particular of juveniles, which represent the bulk of the population and whose survival has the greatest effect on population growth. One of the major global threats to sea turtles is incidental bycatch, although not all animals die in the process. This is particularly acute for the loggerhead sea turtle (Caretta caretta). Here fisheries-dependent monitoring is used to seek insights into patterns of survival at multiple Mediterranean foraging areas: north and south Adriatic, north Ionian, and the Tunisian shelf. Annual survival probability was estimated using the catch curve method. Size data of 2191 loggerhead turtles ranging from 19 to 92cm curved carapace length were converted to age according to eight age-size curves available from the Mediterranean Sea. The mean annual survival probabilities for the four areas were heterogeneous and ranged between 0.710 and 0.862. Results suggest that the survival probabilities for Mediterranean loggerheads, especially in some areas, are lower than would be expected from a healthy population. This is of particular concern for the Greek rookeries, which appear most affected by anthropogenic mortality occurring in the study areas. This supports the implementation in those areas of measures mitigating the main threats, notably bycatch

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The first ‘lost year’ of Mediterranean sea turtles: dispersal patterns indicate subregional management units for conservation

Cited by 52 publications

References 48 publications

Movement patterns of marine turtles in the Mediterranean Sea: a review

Movement patterns of marine turtles in the Mediterranean Sea: a review

Active dispersal in loggerhead sea turtles ( Caretta caretta ) during the ‘lost years’

Annual survival probabilities of juvenile loggerhead sea turtles indicate high anthropogenic impact on Mediterranean populations

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