scholarly journals Use of skeletochronological analysis to estimate the age of leatherback sea turtles Dermochelys coriacea in the western North Atlantic

2009 ◽  
Vol 8 ◽  
pp. 165-177 ◽  
Author(s):  
L Avens ◽  
JC Taylor ◽  
LR Goshe ◽  
TT Jones ◽  
M Hastings
Keyword(s):  
North Atlantic ◽  
Sea Turtles ◽  
Dermochelys Coriacea ◽  
Leatherback Sea Turtles

scholarly journals Orientation behaviour of leatherback sea turtles within the North Atlantic subtropical gyre

2015 ◽  
Vol 282 (1804) ◽  
pp. 20143129 ◽  
Author(s):  
Kara L. Dodge ◽  
Benjamin Galuardi ◽  
Molly E. Lutcavage
Keyword(s):  
North Atlantic ◽  
Sea Turtles ◽  
Sensory Information ◽  
Subtropical Gyre ◽  
Dermochelys Coriacea ◽  
Male Adult ◽  
The North ◽  
The North Atlantic ◽  
Leatherback Sea Turtles ◽  
Nesting Beaches

Leatherback sea turtles ( Dermochelys coriacea ) travel thousands of kilometres between temperate feeding and tropical breeding/over-wintering grounds, with adult turtles able to pinpoint specific nesting beaches after multi-year absences. Their extensive migrations often occur in oceanic habitat where limited known sensory information is available to aid in orientation. Here, we examined the migratory orientation of adult male, adult female and subadult leatherbacks during their open-ocean movements within the North Atlantic subtropical gyre by analysing satellite-derived tracks from fifteen individuals over a 2-year period. To determine the turtles' true headings, we corrected the reconstructed tracks for current drift and found negligible differences between current-corrected and observed tracks within the gyre. Individual leatherback headings were remarkably consistent throughout the subtropical gyre, with turtles significantly oriented to the south-southeast. Adult leatherbacks of both sexes maintained similar mean headings and showed greater orientation precision overall. The consistent headings maintained by adult and subadult leatherbacks within the gyre suggest use of a common compass sense.

Fishing methods to reduce sea turtle mortality associated with pelagic longlines

2005 ◽  
Vol 62 (5) ◽  
pp. 965-981 ◽  
Author(s):  
John W Watson ◽  
Sheryan P Epperly ◽  
Arvind K Shah ◽  
Daniel G Foster
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Sea Turtles ◽  
Capture Rate ◽  
Sea Turtle ◽  
Mitigation Measures ◽  
Dermochelys Coriacea ◽  
Primary Target ◽  
Negative Effect ◽  
Catch Rates

Changes in hook design and bait type were investigated as measures to reduce the bycatch of sea turtles on pelagic longlines in the western North Atlantic Ocean. Specifically, the effectiveness of 18/0 circle hooks and mackerel (Scomber scombrus) bait was evaluated with respect to reducing sea turtle interactions and maintaining swordfish (Xiphias gladius) and tuna (Thunnus spp.) catch rates. Individually, circle hooks and mackerel bait significantly reduced both loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtle bycatch. Circle hooks also significantly reduced the rate of hook ingestion by the loggerheads, potentially reducing postrelease mortality. The combination of circle hooks and mackerel bait was even more effective for loggerhead turtles and had no negative effect on swordfish catch. These modifications in fishing methods, in conjunction with tools developed to remove hooks and line from the turtles, significantly reduced the capture rate of sea turtles and potentially the post-hooking mortality of those that were caught and did not negatively impact the primary target species catch rate. In addition, these mitigation measures have the potential to reduce mortality of sea turtles and other bycatch species worldwide.

COCCIDIAL INFECTION OF THE ADRENAL GLANDS OF LEATHERBACK SEA TURTLES (DERMOCHELYS CORIACEA)

2016 ◽  
Vol 52 (4) ◽  
pp. 874-882 ◽  
Author(s):  
Sara D. Ferguson ◽  
James F. X. Wellehan ◽  
Salvatore Frasca ◽  
Charles J. Innis ◽  
Heather S. Harris ◽  
...  
Keyword(s):  
Adrenal Glands ◽  
Sea Turtles ◽  
Dermochelys Coriacea ◽  
Coccidial Infection ◽  
Leatherback Sea Turtles

Tursiocola neliana sp. nov (Bacillariophyceae) epizoic on South African leatherback sea turtles (Dermochelys coriacea) and new observations on the genus Tursiocola

Phytotaxa ◽  
2020 ◽  
Vol 453 (1) ◽  
pp. 1-15 ◽  
Author(s):  
ROKSANA MAJEWSKA
Keyword(s):  
Sea Turtles ◽  
Central Area ◽  
Sea Turtle ◽  
Dermochelys Coriacea ◽  
Eastern Coast ◽  
New Taxon ◽  
Freshwater Turtles ◽  
Diatom Genus ◽  
Leatherback Sea Turtles ◽  
Internal Side

Tursiocola, a presumably exclusively epizoic diatom genus, comprises species found on various aquatic animals such as cetaceans, manatees, and marine and freshwater turtles. The genus is characterised by linear or lanceolate valves with well-developed pseudosepta at both poles, a valvocopula with three pairs of siliceous tabs, and a butterfly-like structure extending from the central nodule on the internal side of the valve. The current study describes a novel species of Tursiocola, T. neliana Majewska sp. nov. that grows epizoically on leatherback sea turtles from the Eastern Coast of South Africa based on detailed observations using light and scanning electron microscopy. The new taxon resembles the other currently known sea turtle-associated Tursiocola species in possessing relatively small, slightly heteropolar valves with acute apices and a strongly reduced butterfly structure on the internal side. However, T. neliana differs from all other members of the genus in being distinctly dorsiventral, with a clearly bowtie-shaped central area, unequal stria density on two sides of the raphe-sternum, and up to 8 areolae per stria. The description of the new taxon brings the total number of the sea turtle-associated Tursiocola species known so far up to four. An emended description of Tursiocola is proposed based on the new observations presented in this and other recent reports. Furthermore, the current understanding of the genus ecology is summarised.

scholarly journals Behaviour of leatherback sea turtles, Dermochelys coriacea , during the migratory cycle

2005 ◽  
Vol 272 (1572) ◽  
pp. 1547-1555 ◽  
Author(s):  
Michael C James ◽  
Ransom A Myers ◽  
C. Andrea Ottensmeyer
Keyword(s):  
Sea Turtles ◽  
Satellite Telemetry ◽  
Biological Significance ◽  
Dermochelys Coriacea ◽  
Behavioural Patterns ◽  
Nesting Behaviour ◽  
Migratory Cycle ◽  
Leatherback Sea Turtles ◽  
Migratory Patterns ◽  
Nesting Beaches

Leatherback sea turtles, Dermochelys coriacea , undertake broad oceanic movements. While satellite telemetry has been used to investigate the post-nesting behaviour of female turtles tagged on tropical nesting beaches, long-term behavioural patterns of turtles of different sexes and sizes have not been described. Here we investigate behaviour for 25 subadult and adult male and female turtles satellite-tagged in temperate waters off Nova Scotia, Canada. Although sex and reproductive condition contributed to variation in migratory patterns, the migratory cycle of all turtles included movement between temperate and tropical waters. Marked changes in rates of travel, and diving and surfacing behaviour, accompanied southward movement away from northern foraging areas. As turtles approached higher latitudes the following spring and summer, they assumed behaviours consistent with regular foraging activity and eventually settled in coastal areas off Canada and the northeastern USA. Behavioural patterns corresponding to various phases of the migratory cycle were consistent across multiple animals and were repeated within individuals that completed return movements to northern waters. We consider the potential biological significance of these patterns, including how turtle behaviour relates to predator avoidance, thermoregulation and prey distribution.

scholarly journals The acoustic identification and enumeration of scyphozoan jellyfish, prey for leatherback sea turtles (Dermochelys coriacea), off central California

2010 ◽  
Vol 67 (8) ◽  
pp. 1739-1748 ◽  
Author(s):  
Tanya R. Graham ◽  
James T. Harvey ◽  
Scott R. Benson ◽  
Josiah S. Renfree ◽  
David A. Demer
Keyword(s):  
Sea Turtles ◽  
Dermochelys Coriacea ◽  
Target Strength ◽  
Diameter Distribution ◽  
Bell Diameter ◽  
Leatherback Turtles ◽  
Central California ◽  
Leatherback Sea Turtles ◽  
Acoustic Identification ◽  
Scyphozoan Jellyfish

Abstract Graham, T. R., Harvey, J. T., Benson, S. R., Renfree, J. S., and Demer, D. A. 2010. The acoustic identification and enumeration of scyphozoan jellyfish, prey for leatherback sea turtles (Dermochelys coriacea), off central California. – ICES Journal of Marine Science, 67: 1739–1748. Acoustic-sampling techniques were developed to estimate the abundance and distribution of scyphozoan jellyfish, prey for leatherback turtles foraging off central California. Acoustic data were analysed from regions where jellyfish were present or absent from corresponding net tows. Empirical data on bell-diameter distribution (mean 26.2 cm; s.d. 10.6) were used to estimate target strength (TS; dB re 1 m2) at 18, 38, 70, 120, and 200 kHz using a distorted-wave Born approximation scattering model. TS measurements of in situ animals at 38 and 200 kHz averaged −63.9 and −70.5 dB, compared with the model estimates of −54.9 and −64.0 dB, respectively. The model estimates of TS at 18, 70, and 120 kHz were −53.9, −59.9, and −61.8 dB, respectively. Using these TS estimates, an algorithm was developed to extract jellyfish echoes from total acoustic backscatter. Echo-integration methods applied to regions where net catches contained jellyfish resulted in an estimate of mean numerical abundance of 3217 jellyfish (s.d. 2276) with a mean density of 251 522 jellyfish nautical mile−2 (s.d. 57 504) and a mean concentration of 0.003 jellyfish m−3 (s.d. 0.002). The novel methods developed will help characterize prey resources for leatherback turtles off central California.

Sign in / Sign up

Export Citation Format

Share Document