The diet of pelagic loggerhead sea turtles (Caretta caretta) off the Balearic archipelago (western Mediterranean): relevance of long-line baits

2007 ◽  
Vol 87 (3) ◽  
pp. 805-813 ◽  
Author(s):  
M. Revelles ◽  
L. Cardona ◽  
A. Aguilar ◽  
G. Fernández
Keyword(s):  
Continental Shelf ◽  
Feeding Habits ◽  
Sea Turtles ◽  
Stomach Contents ◽  
Caretta Caretta ◽  
Western Mediterranean ◽  
Gut Content ◽  
Loggerhead Sea Turtles ◽  
Isotopic Signatures ◽  
Central Regions

Gut content and stable isotope analyses were used to investigate the feeding habits of loggerhead sea turtles (Caretta caretta) inhabiting the Balearic archipelago. Turtles caught in the pelagic realm (δ13C: -16.0±0.6‰ and δ15N: 8.5±0.9‰) and turtles caught on the continental shelf (δ13C: -16.7±0.6‰ and δ15N: 8.4±1.3‰) did not differ in their isotopic signatures, suggesting that their diets include the same prey types. A mixing model revealed that for the turtles here analysed, squid and the jellyfish Cotylorhiza tuberculata were the most relevant prey, although stomach contents analysis revealed that carnivorous jellyplankton, neuston, fish and other cephalopods were also consumed. Gut content analysis also indicated that most of the prey identified, including all fish and most cephalopods, were of pelagic origin. Thus, loggerhead sea turtles inhabiting central regions of the western Mediterranean appear to seldom exploit benthic prey, even while on the continental shelf.

Interaction between loggerhead sea turtles (Caretta caretta) and marine litter in Sardinia (Western Mediterranean Sea)

2014 ◽  
Vol 100 ◽  
pp. 25-32 ◽  
Author(s):  
Andrea Camedda ◽  
Stefano Marra ◽  
Marco Matiddi ◽  
Giorgio Massaro ◽  
Stefania Coppa ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Sea Turtles ◽  
Caretta Caretta ◽  
Western Mediterranean ◽  
Loggerhead Sea Turtles ◽  
Marine Litter ◽  
Western Mediterranean Sea

scholarly journals Skeletochronology, age at maturity and cause of mortality of loggerhead sea turtles Caretta caretta stranded along the beaches of Campania (south-western Italy, western Mediterranean Sea)

Herpetozoa ◽  
2020 ◽  
Vol 33 ◽  
pp. 39-51 ◽  
Author(s):  
Fabio Maria Guarino ◽  
Fabio Di Nocera ◽  
Francesco Pollaro ◽  
Giorgio Galiero ◽  
Doriana Iaccarino ◽  
...  
Keyword(s):  
Sea Turtles ◽  
Follicular Development ◽  
Caretta Caretta ◽  
Development Stage ◽  
Western Mediterranean ◽  
Anthropogenic Factors ◽  
Loggerhead Sea Turtles ◽  
Western Mediterranean Sea ◽  
Conservation Actions ◽  
Management And Conservation

Information on demographic and life-history traits of endangered vertebrate species, such as sea turtles, is crucial for planning management and conservation actions. We applied skeletochronology of phalanges to estimate the age of loggerhead turtles, Caretta caretta, found dead stranded along the beaches of Campania (western Mediterranean) from 2013 to 2017. To obtain maturity data, we examined gonads from a subsample of 7 males and 11 females. Overall, curved carapace length (CCL) ranged from 5.6 to 90.8 cm, but for most turtles (89%) it was 50–79.9 cm. Predominance of stranded females (62%) was recorded. Ten out of the eighteen histologically examined gonads allowed estimating maturity. Based on the lines of arrested growth counting, the estimated age of the examined specimens ranged from 0 (hatchling) to 26 years. The modal age was 14 years for males and 17 years for females. The smallest male with spermatogenetic activity had a CCL of 65 cm and was estimated to be 16 years old. The smallest female with follicular development stage, characterising the transition towards adulthood, had a CCL of 69.5 cm and was estimated to be 20 years old. Anthropogenic factors were responsible for 36% of the mortality of individuals, followed by parasitic/infective pathologies (20%).

Smaller longer, larger shorter: energy budget calculations explain intrapopulation variation in remigration intervals for loggerhead sea turtles (Caretta caretta)

2008 ◽  
Vol 86 (7) ◽  
pp. 595-600 ◽  
Author(s):  
Hideo Hatase ◽  
Katsumi Tsukamoto
Keyword(s):  
Feeding Habits ◽  
Sea Turtles ◽  
Caretta Caretta ◽  
Sea Turtle ◽  
Energy Budgets ◽  
Loggerhead Sea Turtles ◽  
Intrapopulation Variation ◽  
Turtle Population ◽  
The Difference ◽  
And Migration

Adult female loggerhead sea turtles ( Caretta caretta (L., 1758)) show a size-related behavioural and trophic dichotomy within several populations: oceanic planktivory by small females and neritic benthivory by large females. Within a Japanese population, smaller females have longer remigration intervals (the intervals between successive nesting years) than larger females. We hypothesized that this is attributed to the size-related foraging dichotomy, and calculated energy budgets and food requirements for the small and large females. Total reproductive energy costs for the small and large females were 1003 and 434 MJ, equivalent to 4043 kg of planktonic items and 275 kg of benthic items, respectively. The minimum durations necessary for accumulating the total reproductive energy for the small and large females were 430 and 26 days, equivalent to remigration intervals of 2 years and 1 year taking into account the nesting and migration durations and seasonal reproduction. Therefore, it was theoretically demonstrated that the intrapopulation variation in remigration intervals for Japanese loggerheads could be caused by the difference in their feeding habits, implying that remigration dynamics in a sea turtle population that shows a foraging dichotomy is regulated by feeding conditions not in a single habitat but in multiple habitats.

Feeding habits of the sea turtles Caretta caretta and Lepidochelys olivacea in south-eastern Brazil

2015 ◽  
Vol 8 ◽  
Author(s):  
Ana Paula Madeira Di Beneditto ◽  
Jailson Fulgencio De Moura ◽  
Salvatore Siciliano
Keyword(s):  
Rio De Janeiro ◽  
Feeding Habits ◽  
Sea Turtles ◽  
Stomach Contents ◽  
Caretta Caretta ◽  
Small Scale ◽  
Lepidochelys Olivacea ◽  
South Eastern ◽  
Eastern Brazil ◽  
Janeiro State

Studies of the feeding habits of sea turtles are important in identifying their feeding grounds and preferred prey, thus helping with management decisions regarding habitat protection. The present study describes, for the first time, the feeding habits of the sea turtlesCaretta carettaandLepidochelys olivaceain Rio de Janeiro State, south-eastern Brazil (22°06′S–22°55′S). The stomach contents of fiveC. carettaand fiveL. olivacearecovered between 2009 and 2010 were analysed to identify the prey species. A common feeding pattern was noted for both species, with bottom-dwelling prey (fish, crustaceans, molluscs and echinoderms), common in shallow environments, constituting the main food items. All fish and brachyuran crustacean species identified in the stomach contents were by-catch in small-scale shrimp fisheries that operate along the study area. The coastal waters of Rio de Janeiro State represent a new feeding ground forL. olivacea, expanding its preferential habitat during the non-reproductive period. The results provide strong evidence for the likelihood that sea turtles are interacting with fisheries due to an overlapping between feeding and fishery grounds. An evaluation of carcasses washed up on beaches is needed for a better understanding of the effects on the population dynamics of sea turtles.

scholarly journals Sources of bycatch of loggerhead sea turtles in the western Mediterranean other than drifting longlines

2009 ◽  
Vol 67 (4) ◽  
pp. 677-685 ◽  
Author(s):  
Irene Álvarez de Quevedo ◽  
Luis Cardona ◽  
Andrea De Haro ◽  
Eva Pubill ◽  
Alex Aguilar
Keyword(s):  
Eastern Mediterranean ◽  
Sea Turtles ◽  
Caretta Caretta ◽  
Western Mediterranean ◽  
Loggerhead Sea Turtles ◽  
Bottom Trawling ◽  
Electivity Index ◽  
Fishing Vessels ◽  
Fishing Gears ◽  
Bottom Trawler

Abstract Álvarez de Quevedo, I., Cardona, L., De Haro, A., Pubill, E., and Aguilar, A. 2010. Sources of bycatch of loggerhead sea turtles in the western Mediterranean other than drifting longlines. – ICES Journal of Marine Science, 67: 677–685. A survey, including questionnaires to fishers and observers on board fishing vessels, was conducted to assess turtle bycatch in the waters off Catalonia (northeastern Spain), a region inhabited mainly by loggerhead sea turtles (Caretta caretta) from the highly endangered eastern Mediterranean rookeries. Observer reports confirmed that the data produced by the interviewees were reliable, so interview results were used to estimate turtle bycatch. The number of turtles caught monthly per vessel was estimated at 0.01 for bottom longlines, 0.02 for trammelnets, 0.07 for bottom trawling, and 1.2 for drifting longlines. From these values, 481 (95% CI: 472–491) turtles were estimated to be taken annually as bycatch by the whole fleet. Bottom trawling and trammelnets were the most widely used fishing gears (33 and 31% of the total 11 237 fishing months), but most turtles were caught either by bottom trawlers (249; 95% CI 83–415) or by drifting longlines (124; 95% CI: 40–199). Ivlev's electivity index revealed that bottom trawler bycatch was higher than expected in areas with a wide continental shelf. Given the heavy turtle mortality associated with bottom trawling and the fact that, in southern Catalonia, the fleet mainly takes turtles from western Mediterranean rookeries, it is suggested that the fishery be regulated through winter fishing restrictions, reducing the number of bottom trawlers working in the area, reducing the time the net is in the water to prevent turtle suffocation, or being obliged to use turtle excluder devices.

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