Mean Straight Carapace Length Research Articles

The urban lives of green sea turtles: Insights into behavior in an industrialized habitat using an animal-borne camera.

The cryptic and aquatic life histories of sea turtles have made them a challenging group to directly observe, leaving significant knowledge gaps regarding social behavior and fine-scale elements of habitat use. Using a custom-designed animal-borne camera, we observed previously undocumented behaviors by green turtles (Chelonia mydas) at a foraging area in San Diego Bay, a highly urbanized ecosystem in California, USA. We deployed a suction-cup-attached pop-off camera (manufactured by Customized Animal Tracking Solutions) on 11 turtles (mean straight carapace length = 84.0 ± 11.2 cm) for between 1 and 30.8 h. Video recordings, limited to sunlit hours, provided 73 h of total observation time between May 2022 and June 2023. We observed 32 conspecific interactions; we classified 18 as active, entailing clear social behaviors, as compared with 14 passive interactions representing brief, chance encounters. There was no evidence for agonistic interactions. The camera additionally revealed that green turtles consistently use metal structures within urban San Diego Bay. In seven instances, turtles exhibited rubbing behavior against metal structures, and we observed two examples of turtles congregating at these structures. High rates of intraspecific interaction exhibited relatively consistently among individuals provide a compelling case for sociality for green turtles in San Diego Bay, adding to a growing research base updating their historical label of "non-social." The frequent use of metal structures by the population, in particular the rubbing of exposed skin, has implications for behavioral adaptations to urban environments. Our study exemplifies the promise of technological advances (e.g., underwater and animal-borne cameras) for updating natural history paradigms, even for well-studied populations.

Dichotomy in morphology of the same genetic lineage of green turtles

Morphological studies of marine turtles are important to provide insight into changes in their developmental environment. This study aimed to determine green turtles' Chelonia mydas morphological differences within the same genetic lineage in the eastern Mediterranean MED3 management unit and to find the best conversion equations between carapace size. A total of 106 adult green turtles (curved carapace length [CCL] range 79–105 cm) were measured on the five major nesting beaches of the eastern Mediterranean during 2020 and 2021. Morphological differences were tested with PERMANOVA and the relationship among body sizes was tested by linear regression. In the eastern Mediterranean green turtles, the mean CCL and SCL (straight carapace length) were 88.5 cm and 83.5 cm, respectively. There were no statistically significant differences in any of the examined morphological characteristics of green turtles collected from five nesting beaches. In the clustering analysis, however, it was found that all the turtles fell into two distinct groups: larger (> 95.2 cm) and smaller (< 85.2 cm) turtles. As well, the conversion equations between CCL and SCL showed a high coefficient of determination (R2 = 0.938). We suggest that the conversion equations may be applied to all green turtles belonging to this population and nesting in the eastern Mediterranean. Keywords: Chelonia mydas, morphology, conversion equation, K-means, eastern Mediterranean

Twenty-year changes in the composition of a mixed stock of foraging green turtles in the Yaeyama Islands of Japan

Recent studies have shown an increasing mean straight carapace length (SCL) of foraging green turtles Chelonia mydas around the Yaeyama Islands, Japan, compared to that of 20 yr ago. This trend is attributed to reduced juvenile mortality resulting from a decline in sea turtle fisheries. In this Yaeyama foraging aggregation, the proportions of turtles originating from different populations (genetic stocks) are known to vary according to size; for turtles originating from the Ryukyu Archipelago and Ogasawara (Japanese populations), the proportion in the 50-70 cm SCL size class is higher than that in the <50 cm SCL size class. Here, we compared the natal origin compositions of the Yaeyama foraging aggregation from 2 sampling periods (1997-1999 and 2016-2018) across 2 size categories (<55 and >55 cm SCL) and investigated the relationship between the size increase and changes in natal origins. The results showed that the proportion of the Japanese populations has recently increased compared to that 20 yr ago. The size distribution, based on the natal origin of each turtle in 2016-2018 estimated using single nucleotide polymorphisms, showed that the proportion of populations at latitudes lower than Japan with a ≥55 cm SCL decreased substantially, whereas the proportion of the Japanese populations remained stable between size categories. These results suggest a link between the size increase and the increase in Japanese turtles. This study also provides the detailed composition of the Yaeyama foraging aggregation, including the size distributions and sex ratios of contributing populations.

Morphological Divergence of Hermann's Tortoise (Testudo hermanni boettgeri Mojsisovits, 1889) in Albania.

Simple SummaryThe morphology of chelonians provides basic information about development, evolution, biodiversity, biomechanics, behavior, ecology, and physiology. Furthermore, it has also played an important role in characterizing populations and analyzing the similarities between populations. This study investigates the morphological variation of Hermann’s tortoise (Testudo hermanni boettgeri Mojsisovits, 1889) between specimens from five different populations in Albania. It also provides basic data on the morphological characteristics of the Hermann’s tortoise. Hermann’s tortoise in the Albanian population were regionally diverged into three different populations that were situated in northern (Shkodra), central (Tirana, Berati, and Ballshi), and southern (Saranda) Albania. Moreover, female individuals were larger and heavier than male individuals, and the females followed Bergmann’s rule. The morphological divergences may be due to molecular variations or environmental conditions of the regions.Testudines show phenotypic plasticity, and variation among specific populations within a species is widespread. Morphological differences between populations may reflect ecological factors that drive adaptation to local conditions. In this context, we gathered basic data on the morphology of the Hermann’s tortoise (Testudo hermanni boettgeri Mojsisovits, 1889) to document their variation across different geographical regions. We surveyed Hermann’s tortoises in five different locales within Albania during April and May 2020 and measured 20 morphological characteristics, including carapace and plastron dimensions. We measured 188 tortoises (81 males, 107 females) in this study, and females were larger (p = 0.0001) and heavier (p = 0.0001) than males. Mean straight carapace length (SCL) and body mass were 172.4 mm and 1128.8 g, respectively, for females, and 151.3 mm and 735 g, respectively, for males. The Albanian T. h. boettgeri were regionally diverged into three different populations that were situated in northern (Shkodra), central (Tirana, Berati, and Ballshi), and southern (Saranda) Albania. The body size (curved carapace length (CCL)) of females was positively correlated (r = 0.216; p = 0.025) with the latitude, in accordance with Bergmann’s rule. However, there was no correlation between body size and latitude in males. These striking regional differences among Albanian T. h. boettgeri strongly suggest that further study of molecular variations and reproductive output of Hermann’s tortoises is warranted.

First Report of Occurrence and Conservation Status of Black Softshell Turtle, Nilssonia nigricans (Anderson 1875) (Reptilia: Testudines: Trionychidae) in West Bengal, India

The study reports the first record of the Black softshell turtle, Nilssonia nigricans (Anderson in Ann Mag Nat Hist 16:282–285, 1875), a species categorised as “Extinct in the Wild” category by IUCN ( http://www.iucnredlist.org/ , 2002) from a locality in West Bengal (Baneswar village, District Cooch Behar, West Bengal; 26° 23.912′ N, 089° 29.872′ E). The study conducted during January, 2017 to January, 2020 found the species to occur in a protected temple pond and several other ponds in the locality. The mean Straight Carapace Length (SCL) and the mean Straight Carapace Width (SCW) of adult turtles were 47.3 ± 10.11 and 37.66 ± 4.24 respectively, whereas the mean SCL and SCW of juveniles were 13.5 ± 6.36 and 12 ± 4.24 respectively. The species is omnivorous in feeding habit. It enjoys local community protection. Further conservation efforts are required to save this local population from future extinction due to urbanization pressure.

Population Status of Green Turtles (Chelonia mydas) Foraging in Arica Bay, Chile1

Population characteristics and carapace growth rates were estimated for green turtles (Chelonia mydas) foraging in Arica Bay, northern Chile, from 2012 to 2016. Within the main foraging area of La Puntilla, an open population of up to 514 individuals was estimated by mark and recapture (Jolly-Seber method), with densities of 20–225 individuals/km2. Captured individuals (n = 159) ranged from 44.6 to 98.6 cm straight carapace length (SCL) with a mean SCL of 64.9 cm (SD 10.8); most turtles were juveniles; however, 10 were adults with SCL > 80 cm (three of these being males). A mean body condition index (BCI) of 1.64 (range 0.34–3.63) indicated healthy population conditions, with mean annual growth rates (AGR) of 4.6 cm/year (SD 2.97). The consistent presence of turtles between 2012 and 2016 and the relatively high abundance compared to the general situation reported for the species in Chile makes Arica Bay the most important feeding congregation of green turtles in the country. The population's healthy state and size, its location within an urban radius, and the multiple human uses of this site represent aspects that must be considered in protection and development plans for the city's coastal border.

Distribution, Size, and Demographics of Eastern Hermann's Tortoise, Testudo hermanni boettgeri, in Turkey

Conserving and managing an imperiled species, such as Testudo hermanni, requires information on population status and demographic traits. To acquire this information, we surveyed Hermann's tortoises, Testudo hermanni boettgeri, in European Turkey from April to October 2014–2016. We found 283 (135 males, 102 females, 45 juveniles, and 1 unknown) T. h. boettgeri at 34 locations. Of these sites, 29% included at least 1 individual. We found that females were larger and heavier (mean straight carapace length [SCL] = 175.4 mm, body mass = 1234.1 g) than males (SCL = 153.2 mm, body mass = 849.6 g). The age frequency had a normal Gaussian distribution with 11–15 yrs being the most common. Elevation at capture sites ranged from 22 to 380 m above sea level. Illegal overharvesting for the pet trade appears to have caused no reduction in body size.

Demography of Marine Turtles in the Nearshore Environments of the Northern Mariana Islands

In the western Pacific, green ( Chelonia mydas ) and hawksbill ( Eretmochelys imbricata ) sea turtles are listed as Endangered under the U.S. Endangered Species Act (ESA). Population data are limited for both species throughout the entire region and particularly in the Philippine Sea. This study characterizes size class distribution, growth rates, habitat use, behavior, diet, and site fidelity of foraging aggregations of green and hawksbill turtles in nearshore habitats of Saipan, Tinian, and Rota in the Commonwealth of the Northern Mariana Islands (CNMI). Between August 2006 and February 2014, we captured 642 turtles (493 green and 36 hawksbill turtles). Straight carapace length (SCL) ranged from 32.5 to 91.6 cm, with juveniles composing the majority of captures (mean SCL = 50.7 cm). Four of the green turtles were adults (SCL ≥ 81 cm), with SCLs of 84.2 to 91.6 cm. All 36 hawksbill turtles were juveniles (SCL Amansia sp., Gelidiella sp., Hypnea sp., and Ceramium sp. Green turtle growth rates ranged from 0.3 to 7.8 cm yr-1. Estimated mean residency time was 17 yr. This is the first study within the CNMI to report on morphometric data and diet composition of marine turtles. These results provide an assessment of green and hawksbill turtle population demographics and habitat use in the CNMI.

Change in population structure, growth and mortality rate of juvenile green turtle (Chelonia mydas) after the decline of the sea turtle fishery in Yaeyama Islands, Ryukyu Archipelago

The Yaeyama Islands provide habitat for juvenile green turtles originating from various rookeries in the western Pacific. The sea turtle fishery has been declining since 2004 due to the retirement of sea turtle fishermen in the region. We investigated the population ecology of green turtles based on capture–mark–recapture data from 1995 to 2016. The effect of the past sea turtle fishery on the green turtle population was analyzed by comparing the population structure, growth and mortality rates during 1995–2003, with those of the population in 2004–2016. Mean straight carapace lengths of green turtles in 1995–2003 were 51.5 cm (SD = 10.9, range 34.0–102.4, N = 838), annual growth rates were 2.7 cm year−1 (SD = 1.31, range 0.09–5.32, N = 50), and mortality rates were 0.25 year−1 (95% CI 0.20–0.30). In comparison, mean straight carapace length of green turtles in 2004–2016 was 55.5 cm (SD = 12.1, range 6.2–96.5, N = 595), growth rates were 2.24 cm year−1 (SD = 0.78, range 0.79–4.17, N = 67) and mortality rates were 0.15 year−1 (95% CI 0.11–0.19). Carapace size increased and annual growth and mortality rates decreased after 2004. The increase in the number of larger-sized green turtles and the decrease in mortality rates were likely effects of the decline in the sea turtle fishery.

Using minimally invasive techniques to determine green sea turtle Chelonia mydas life-history parameters

Determining the life history and population parameters of sea turtles typically involves the live capture of animals. Photo-identification (photo-ID) of free-ranging individuals is a cost-effective alternative to conventional tagging for mark-recapture studies that also minimises the risk of injury or stress to the animals. Paired laser-photogrammetry (photogrammetry) is a minimally invasive technique to size animals and has been proven effective in a range of different taxa. Photo-ID and photogrammetry were combined as minimally invasive techniques to determine life-history parameters of free-ranging green sea turtles Chelonia mydas at a site in Oslob, Cebu, Philippines. The pattern-recognition software I3S Pattern was used to validate results and confirm visual matching. A total of 38 individuals were identified at the site through photo-ID. Facial scutes remained unchanged for a min. of 3.6years. Photogrammetry was employed to measure straight carapace lengths (SCLs) of a sample of 17 individuals, with a mean straight carapace length of 52.5±SD 1.1cm. Modified maximum likelihood methods were used to model mean residency of 873d at the site, with c. 12 individuals present at any one time. Based on photogrammetry measurements, individuals at the site were found to be of immature age class. This, along with the extended residency times, indicates that the site could be an important developmental habitat. Photo-ID is a valid minimally invasive technique for identifying individual C. mydas for mark-recapture analyses. The use of paired laser photogrammetry for categorising the life-history stage of an aggregation of sea turtles is demonstrated for the first time. Identification of such developmental habitats through the employment of these minimally invasive techniques is useful for conservation of the species.

New findings about the spatial and temporal use of the Eastern Atlantic Ocean by large juvenile loggerhead turtles

AbstractAimsEffective conservation of threatened or endangered species requires a robust understanding of their spatio‐temporal distribution. Although a huge amount is known about the movements of Atlantic adult sea turtles, much less is known about juvenile turtles, and much of the life history model is therefore inferred. We set out to describe the spatio‐temporal distribution of juvenile loggerheads turtles found around the Canary Islands.LocationEastern North Atlantic Ocean.MethodsBetween 1999 and 2012, we satellite‐tracked 24 healthy large juvenile loggerhead turtles (mean straight carapace length = 47.4 cm, range = 34.6–54.5 cm) captured in the waters around the Canary Islands. We describe their regional distribution, identify high‐use areas and create a model for habitat suitability using minimum convex polygons, density rasters and ensemble ecological niche modelling, integrated with physical and biological environmental data.ResultsTurtles used a huge oceanic area (2.5 million km2) with particularly high usage around the Canary Islands, Spain, Portugal, Morocco and Western Sahara. In spring and summer, turtles generally moved further north towards the Iberian Peninsula. Ecological niche modelling identified sea surface temperature as the most important contributory variable to the habitat models. We also recorded three juvenile turtles making westward migrations away from the eastern Atlantic Ocean, presumably back towards their original natal beaches near sexual maturity.Main conclusionsThe results of the present study provide insight into a significant knowledge gap on the spatio‐temporal distribution of large juvenile loggerhead turtles in the eastern Atlantic Ocean. The data highlight that turtles occupy a vast open oceanic area, which hampers the ability of static conservation approaches to afford effective protection. However, ensemble ecological niche modelling highlights key suitable habitat for juvenile loggerhead turtles, which could be used in dynamic conservation protection.

Population structure and allometry of Podocnemis unifilis (Testudines, Podocnemididae) in a protected area upstream Belo Monte dam in Xingu River, Brazil.

Amazon river turtles are increasingly threatened by habitat loss and alteration due to the Brazilian energy policy based on construction of hydroelectric dams, meanwhile, populational studies remain scarce. We described the population structure, and established body allometric relationships of Podocnemis unifilis in the Terra do Meio Ecological Station in the Iriri River, tributary of the Xingu River upstream the Belo Monte dam under construction Turtles were captured by hand net and diving in 2012 and 2013 dry seasons, and 2013 rainy season. A total of 728 males, 296 females and four juveniles were captured. Adult sex ratio was male-biased by 9.15 ♂:1 ♀. Females were significantly larger than males. Mean straight carapace length was 268.9 ± 46.7 mm (165 - 403) for females; and 232.7 ± 24.8 mm (167 - 303) for males. The sexes were morphologically distinct in function of a proportionally larger plastron, and higher carapace, on females. Allometric relationships between straight carapace length and other morphometric traits were strong for males (R2 range = 0.87 - 0.96 and females (R2 range =0.79 - 0.98. Exploitation of P. unifilis in biomass extirpated from the Middle Xingu River may be estimated from body parts found post-consumption by the presented regressions.

Long-Term Trends in Loggerhead (Caretta caretta) Nesting and Reproductive Success at an Important Western Atlantic Rookery

The Archie Carr National Wildlife Refuge (ACNWR), located along the central east coast of Florida (USA) in the western North Atlantic, hosts one of the largest loggerhead (Caretta caretta) nesting assemblages in the western Hemisphere. Sea turtle nesting activity has been continuously monitored on this beach for > 31 yrs, representing one of the longest sea turtle reproductive data sets in the world. Between 1982 and 2012, an estimated 358,243 nests were deposited on the ACNWR with an estimated annual mean plus 95% confidence interval of 11,556 ± 1,129 nests. This constitutes 25.4% ± 0.8% of the mean annual Florida Index Nesting Beach Survey loggerhead complement. Mean annual clutch size was 113.9 ± 1.4, resulting in a 55.1% ± 4.0% mean annual hatching success rate and a mean emerging success rate of 53.3% ± 3.7%. The only egg-fate that was statistically correlated with emerging success were eggs washed out by erosion. The loss of eggs by erosion was significantly greater during storm and poststorm years, compared with nonstorm years. Among individual first-time nesting females that were measured, mean straight carapace length was 91.2 ± 0.15 cm and mean curved carapace length was 98.2 ± 0.15 cm. These data suggest that the ACNWR supports the greatest loggerhead nest density per kilometer in Florida, underscoring the importance of the ACNWR as one of the most important nesting habitats for loggerhead turtles in the Western Hemisphere.

An Assessment of Green Turtle (Chelonia mydas) Stocks Along the Texas Coast, with Emphasis on the Lower Laguna Madre

The in-water status of green turtles (Chelonia mydas) in the northwestern Gulf of Mexico has received comparatively little attention in the management and conservation of this species in US waters. We addressed this void via entanglement netting surveys at 3 estuarine areas (Lavaca-Matagorda Bay, the Aransas Bay complex, and the lower Laguna Madre [LLM]) to assess trends in the relative abundance, distribution, and size composition of green turtles in Texas inshore waters during 1991–2010. Overall catch per unit effort (CPUE) in the LLM (1.5 turtles/km-hr) was significantly higher than that observed in the other 2 estuaries and corresponded to general climate patterns and seagrass areal coverage along the Texas coast. Yearly CPUE of green turtles from the LLM exhibited a significant exponential increase from 1991 to 2010, despite variability in capture rate during recent years. Mean straight carapace length (SCL) of green turtles was statistically similar across the 3 study areas and indicative of dominance by juvenile individuals (LLM mean = 42.2 cm SCL). Historical green turtle size data in the LLM also reveal an overall decreasing trend in mean SCL and shift toward an increased percentage of smaller individuals (30–39.9- and 40–49.9-cm SCL size classes). Also, sighting frequency of postpelagic green turtles at the Brazos-Santiago Pass jetties within the LLM during 2009 was roughly 9 times that reported for comparable months during 1992–1993. These results are indicative of enhanced recruitment of neritic green turtles to the northwestern Gulf of Mexico, most likely due to elevated nesting productivity at beaches in Mexico, Florida, the Caribbean, and the western Atlantic. Overall, the lower Texas coast serves as an important developmental foraging habitat for an increasing population of juvenile green turtles in the northwestern Gulf of Mexico.

Intake passage time, digesta composition and digestibility in East Pacific green turtles ( Chelonia mydas agassizii) at Gorgona National Park, Colombian Pacific

We investigated the food digestibility of East Pacific green turtles, Chelonia mydas agassizii, at tropical coral reefs of Gorgona National Park in the Colombian Pacific and calculated the intake passage time (IPT) of 3 different diets. We collected 150 faecal samples from turtles (mean straight carapace length 61.3 ± 4.12 cm and mean mass 32.3 ± 6.67 kg) to determine digesta composition and for measurement of neutral detergent fibre (NDF), acid detergent fibre (ADF), sulphuric acid lignin and protein. The mean (± S.D) IPT to recover at least 73% of external markers (plastic beads) in the faeces was 23.3 ± 6.6 days. The true NDF digestibility and dry matter digestibility were determined for high protein (fish), plant (fresh leaves of Araceae, Moraceae and Bombaceae) and mixed (combination of both high protein and plant) diets. NDF values obtained for digestibility of the protein, plant and mixed diets were 1%, 63% and 49% respectively. There was a large amount of undigested plant material in the faeces, dominated by fruits of red mangrove ( Rhizophora mangle). We considered the relationships between the type of food, IPT and apparent digestibility in the context of the nutritional contribution of an omnivorous diet. Our results suggest that for juvenile green sea turtles in the Eastern Pacific combined diets are an opportunistic strategy responding to habitat features and supply to maximise energy acquisition in transitional habitats such as Isla Gorgona.

Population estimate and body size of European pond turtles (Emys orbicularis) from Pazarağaç (Afyonkarahisar/Turkey)

AbstractData on population size, adult sex ratio, body size and mass are provided for a population of the turtle Emys orbicularis near Pazarağaç (Afyonkarahisar/Turkey). Using the mark-recapture method (triple catch), a population size of 664 turtles was estimated (95% confidence interval, range 332–996), corresponding to a density of 83 turtles per hectare (range 41.5–124.5). The adult sex-ratio was significantly skewed in favor of males (2.02 males: 1 female; P < 0.001). Almost all recorded specimens were adult (98.1%). Mean straight carapace length (SCL) and body mass (BM) of adult turtles were: SCL = 128.65 mm, BM = 345 g for males (n = 168) and SCL = 135.37 mm, BM = 463 g for females (n = 83).

Stable isotope discrimination (δ13C and δ15N) between soft tissues of the green sea turtle Chelonia mydas and its diet

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 308:271-278 (2006) - doi:10.3354/meps308271 Stable isotope discrimination (δ13C and δ15N) between soft tissues of the green sea turtle Chelonia mydas and its diet Jeffrey A. Seminoff1,*, T. Todd Jones2, Tomoharu Eguchi1, David R. Jones2, Peter H. Dutton1 1NOAA-National Marine Fisheries Service, Southwest Fisheries Science Center, 8604 La Jolla Shores Drive, La Jolla, California 92037, USA 2Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia V6T 1Z4, Canada *Email: jeffrey.seminoff@noaa.gov ABSTRACT: The foraging ecology and movements of vertebrate species have been increasingly studied via stable isotope analyses of small quantities of body tissues. However, the theoretical and experimental basis of this method remains poorly validated for most taxa despite numerous studies using these techniques in natural systems. In this study, we measured stable carbon and stable nitrogen diet–tissue discrimination (Δdt) in whole blood, red blood cells, blood plasma, and epidermis of 8 captive green turtles Chelonia mydas maintained on a control diet (41% protein, 12% lipids, 4% fiber) for 619 d. During the course of the study, mean straight carapace length increased from 45.2 ± 1.2 to 53.7 ± 2.1 cm, whereas mean body mass increased from 11.7 ± 0.7 to 19.9 ± 2.2 kg. Both diet and tissue isotope values remained constant throughout the study, indicating that diet–tissue equilibrium had been achieved. Whereas Δdt13C ranged from –1.11‰ (red blood cells) to +0.17‰ (epidermis), Δdt15N ranged from +0.22‰ (red blood cells) to +2.92‰ (blood plasma). These results contrast with the widely accepted discrimination factors of 0 to 1‰ for δ13C and 3 to 5‰ for δ15N. Comprising the initial enrichment factors available for green turtles, these data will be useful in future interpretations of field isotopic values for this species. KEY WORDS: Carbon · Chelonidae · Ectotherm · Fractionation · Isotope enrichment · Nitrogen · Reptilia Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 308. Online publication date: February 16, 2006 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2006 Inter-Research.

Identifying critical foraging habitats of the green turtle (Chelonia mydas) along the Pacific coast of the Baja California peninsula, Mexico

Abstract The conservation of highly mobile and migratory species remains one of the most serious challenges to resource managers. Intense mortality of immature green turtles has been identified at principal developmental–feeding habitats in Baja California, and is considered a great threat to the stability of the eastern Pacific population. Thus, coastal lagoons of the Baja California peninsula, such as Bahía Magdalena, have been identified as high priority areas for their protection. Conservation efforts to date have focused on creating a sea turtle refuge in the northwestern part of the bay, but this area may not be sufficient for protecting all of the critical feeding areas used by green turtles. The diet of green turtles was investigated through analysis of digestive tract contents from 24 green turtles that were drowned incidentally in fishing nets at feeding grounds in Bahía Magdalena and adjacent areas along the Pacific coast of the Baja California peninsula, Mexico. Mean straight carapace length (SCL) differed significantly between localities: mean: 55.5 cm (range: 47.7–76.9 cm, n=11) in Bahía Magdalena; mean: 67.7 >cm (range: 49–87 cm, n=11) in adjacent coastal waters. Green turtle diet consisted largely of marine algae and seagrasses, but food items varied spatially. The red algae Gracilaria pacifica, Gracilariopsis lemaneiformis and Hypea johnstonii were the most abundant diet items inside Bahía Magdalena, and the seagrass Phyllospadix torreyi was the most commonly ingested food in coastal areas outside of the bay. Results indicate that green turtles utilize spatially distinct foraging habitats within this region. Therefore, it is recommended that any design of protected areas for sea turtles in Bahía Magdalena should consider a regional approach instead of a local approach, taking into account the most important feeding areas used by green turtles at different life stages. Copyright © 2005 John Wiley & Sons, Ltd.

Gross morphometry of young Geochelone sulcata (Testudines: Testudinidae) in Costa Rica

The African Spur tortoise, Geochelone sulcata, has been introduced to Costa Rica. A total of 31 tortoises were measured for 26 gross morphometry parameters. All individuals measured were inmature, aged from 5 to 34 months, and were born in captivity in La Garita de Alajuela, Costa Rica. Mean straight carapace length was 83.1 mm, mean straight plastron length was 68.3 mm and mean maximum height was 46.2 mm. All the measurements were correlated, except tail length and cloacal distance. Weight had the highest positive allometry coefficient. All the variables were joined in two Principal Components; tail length and cloacal distance in Factor 2 and the rest of them in Factor 1. Lack of correlation among tail measures and the other variables as well as their inclusion in a different Factor could be related with an incipient development of sexual dimorphism characters.

Using annual body size fluctuations to explore potential causes for the decline in a nesting population of the loggerhead turtle Caretta caretta at Senri Beach, Japan

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 245:299-304 (2002) - doi:10.3354/meps245299 Using annual body size fluctuations to explore potential causes for the decline in a nesting population of the loggerhead turtle Caretta caretta at Senri Beach, Japan Hideo Hatase1,*, Kiyoshi Goto2, Katsufumi Sato1,**, Takeharu Bando1,***, Yoshimasa Matsuzawa1,****, Wataru Sakamoto1 1Laboratory of Fisheries and Environmental Oceanography, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan 2Minabe Sea Turtle Research Group, 278 Higashiyoshida, Minabe, Wakayama 645-0001, Japan *Email: hatase@kais.kyoto-u.ac.jp Present addresses: **National Institute of Polar Research, 1-9-10 Kaga, Itabashi, Tokyo 173-8515, Japan ***Institute of Cetacean Research, 4-18 Toyomi, Chuo, Tokyo 104-0055, Japan ****Sea Turtle Association of Japan, 5-17-18-302 Nagao-motomachi, Hirakata, Osaka 573-0163, Japan ABSTRACT: The annual recruitment dynamics and body size fluctuations in adult female loggerhead turtles Caretta caretta nesting on Senri Beach in Minabe, Japan from 1990 to 2001 were investigated along with the number of nests, so that the causes for the recent population decline could be assessed. The number of nests decreased from 335 in 1990 to 29 in 1998, and slightly increased thereafter. The recruit percentage (i. e. the percentage of recruits out of total identified females in each year) varied from 39 to 75%. The lack of a significant correlation between the rates of change in the recruit percentage and in the number of nests suggested that the population decline had been caused by factors affecting both recruits and remigrants. The mean straight carapace length (SCL) varied from 825 to 855 mm. The significant negative correlation between the rates of change in the mean SCL and in the number of nests suggested that the decline had been caused by the decrease in the number of small females. The lack of a significant difference in SCL between recruits and remigrants supported the above scenarios. Since small females tend to inhabit the pelagic Pacific irrespective of their recruit or remigrant status, we proposed that the population decline at Senri Beach was attributable to factors operating in the pelagic waters, such as incidental mortality by longline fisheries. KEY WORDS: Loggerhead turtle · Caretta caretta · Nesting population decline · Body size · Recruitment · Senri Beach · Japan Full text in pdf format PreviousExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 245. Online publication date: December 18, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.