Caretta is classified as Endangered (EN - A abd) on the International Union for Conservation of Nature and Natural Resources (IUCN) Red List 2002, listed on Appendix I on Convention on the International Trade in Endangered Species of Flora and Fauna (CITES), Appendix I and II of the Convention of Migratory Species (CMS or Bonn Convention) 1979, Appendix II of the Bern Convention 1979, and Annex II of the EC Habitats Directive. All five species of turtles are protected under Schedule 5 of the Wildlife and Countryside Act 1981 and Schedule 2 of the Conservation (Natural Habitats & c.) Regulations 1994 (Anon. 1999(ii)). This species is particularly susceptible to: bycatch from shrimp trawlers; ingestion of marine debris, and predation on eggs.
A large marine turtle; the largest Egyptian specimen has a carapace length of 1,240 mm. Carapace depressed, slightly elongate, smooth; scutes juxtaposed; posterior edge with moderate indentations; 5 coastal scutes; first marginal scute not in contact with first vertebral scute. Head large, with 2 pairs of prefrontals. There are 2 claws on each limb. Males smaller, with longer tails and larger claws. Color of carapace and dorsal sides of limbs and head reddish brown, some scales may be narrowly edged yellowish. All ventral sided yellowish white.
Caretta caretta is found in nearly all the world's temperate and tropical oceans: the Atlantic Ocean from Newfoundland to Argentina, the Indian Ocean from southern Africa to the Arabian Gulf to western Australia, the Mediterranean Sea, and the Pacific Ocean from Alaska to Chile and Australia to Japan. During winter months loggerhead sea turtles migrate to tropical and subtropical waters.
Biogeographic Regions: indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native ); mediterranean sea (Native )
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Breeding
Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Warmer parts of Atlantic, Pacific, and Indian oceans, and Mediterranean (Bolten et al. 1992) and Caribbean seas. Ranges into temperate zones in summer. Rare or absent far from mainland shores. Major nesting areas are in temperate and subtropical areas in the southeastern U.S., Mexico, Oman, Australia, South Africa, the Mediterranean, and Japan (Dodd 1992). The world's largest nesting aggregation (30,000 nesting females/year) is on Masirah Island, Oman. Nesting range in the U.S. is mainly the Atlantic coast from North Carolina to southern Florida (Shoop 1985, Dodd 1988), with about 90% in Brevard, Indian River, St. Lucie, Martin, Palm Beach, and Broward counties, Florida (CSTC 1990); this is a major nesting area from a global perspective; Indian River and Brevard counties contain the second densest aggregations of nesting loggerheads in the world (about 6000-15,000 females nesting/year). Large numbers occur off primary nesting beaches in Florida during spring and summer (CSTC 1990). Nesting also occurs along Florida's Gulf Coast. Nests regularly in small numbers in Virginia and sometimes north to New Jersey. In recent years a few have nested on barrier islands along the Texas coast. Chesapeake Bay is an important habitat for subadults in summer. Occurs in summer in waters off the northeastern U.S., mainly between Long Island and Cape Hatteras, usually in water less than 60 m deep (Shopp and Kenney 1992). See Seminoff et al. (2004) for information on occurrence in the Gulf of California. See Dodd (1988, 1990) for further details.
Circum-global, within the 10°c oceanic isotherm.
Distribution: Pacific, Indian and Atlantic oceans, Japan, Gulf of Thailand, India, Pakistan, Sri Lanka, Maldives, Solomon Islands [McCoy 2000], Chile, Argentina, Kenya, the British Isles, United Kingdom, and Newfoundland Tunisia, Libya, Egypt, Israel, Eritrea, Tanzania (?), United Arab Emirates (UAE), Somalia, Mauritania, South Africa, tropical western Africa, Cameroon, Madagascar Caribbean and Mediterranean seas (Adriatic Sea: Croatia), Italy [E. RAZZETTI, pers. comm.], Greece (Corfu), France Turkey [Basoglu 1973],Portugal, Australia (North Territory, Queensland, Tasmania, West Australia) SE Mexico (Yucatan, Baja California), Belize, Guatemala, Honduras, Nicaragua, Costa Rica, Panama Colombia [Castro,F. (pers. comm.)] caretta: Atlantic Ocean gigas: Indian and Pacific Ocean acording to the 1994 IUCN Red List of Threatened Animals: EC/NE/NW/SE/SW/WC Atlantic, E/W Indian Ocean, Mediterranean and Black Sea, EC/NE/NW/SE/SW/WC Pacific, Angola, Australia, Bahamas, Bangladesh, Belize, Brazil, Cape Verde, Cayman Islands, China, Colombia, Costa Rica, Cuba, Cyprus, Dominican Republic, Egypt, Greece, Grenada, Guadeloupe, Guatemala, Haiti, Honduras, India, Indonesia, Israel, Italy, Jamaica, Japan, Libya, Madagascar, Mexico, Montserrat, Morocco, Mozambique, Myanmar (= Burma), Namibia, New Caledonia, Nicaragua, Oman, Panama, Papua New Guinea, Philippines, Puerto Rico, Senegal, South Africa, Sri Lanka, St Lucia, Turkey, Turks and Caicos Islands, USA (Alaska, Washington, Western Atlantic: Maine, New Hampshire, Massachusetts, Connecticut, New Jersey, Delaware, Maryland, Virginia, North Carolina, South Carolina, Georgia, Florida), Venezuela, Virgin Islands (British) Two finds in waters of Russia are known: in the Barents Sea's Kolsky Bay and in the Sea of Japan's Peter the Great Bay (fide KHALIKOV, pers. comm.)
Type locality: “Americanas”
Named for their huge heads and powerful jaws, loggerhead turtles are the largest hard-shelled sea turtles alive today. They have a heart-shaped carapace, which is often covered with commensal organisms such as barnacles and algae. Generally, the carapace is a reddish-brown hue with olive tones; there are five pairs of pleural scutes, the first pair touching the cervical (neck) scute. The plastron is cream to yellow, and has two longitudinal ridges that disappear with age. The skin is dull to reddish brown dorsally and medium to pale yellow around the edges and ventrally. The skin may have some orange coloration as well. The skin of males is more brown and the head more yellow than those of females. Males also have wider carapaces and a long curved claw on each forelimb. Loggerhead sea turtle hatchlings tend to be dark brown to reddish brown on the carapace and cream to reddish brown or dark brown on the plastron. The average adult Caretta caretta in the Mediterranean Sea is smaller than the average adult in the Atlantic Ocean. Two subspecies - C. caretta gigas in the Pacific and Indian Oceans and C. caretta caretta in the Atlantic - have been proposed but are not fully accepted. They differ in the number of neural bones in the carapace and marginal scutes on the edge of the carapace. Loggerhead sea turtles differ from other sea turtles in having relatively large heads and reddish coloration. Additionally, Ridley's sea turtles (Lepidochelys) have four inframarginal scutes on the bridge. Green sea turtles (Chelonia mydas) and hawksbill sea turtles (Eretmochelys imbricata imbricata) have only four pairs of pleural scutes on the carapace; the first pleurals do not touch the cervical scute.
Range mass: 77 to 545 kg.
Average mass: 135 kg.
Range length: 213 (high) cm.
Average length: 85-100 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes colored or patterned differently; sexes shaped differently
Length: 92 cm
Weight: 113000 grams
Differs from ridleys in larger size (ridley maximum shell length is 75 cm), reddish-brown dorsal coloration (olive-green or gray in ridleys), and usually 3 poreless scutes on the bridge (usually 4 pored scutes in ridley). Differs from hawksbill and green turtles by having the first costal in contact with the nuchal. Head is relatively large than that of other sea turtles.
Catalog Number: USNM 7778
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Sex/Stage: Sex unknown; Juvenile
Year Collected: 1838
Locality: Funchal, Maderia, Canary Islands, Atlantic Ocean
Belizean Coast Mangroves Habitat
This species is found in the Belizean coast mangroves ecoregion (part of the larger Mesoamerican Gulf-Caribbean mangroves ecoregion), extending along the Caribbean Coast from Guatemala, and encompassing the mangrove habitat along the shores of the Bahía de Annatique; this ecoregion continues along the Belizean coast up to the border with Mexico. The Belizean coast mangroves ecoregion includes the mainland coastal fringe, but is separate from the distinct ecoregion known as the Belizean reef mangroves which are separated from the mainland. This ecoregion includes the Monterrico Reserve in Guatemala, the estuarine reaches of the Monkey River and the Placencia Peninsula. The ecoregion includes the Burdon Canal Nature Reserve in Belize City, which reach contains mangrove forests and provides habitat for a gamut of avian species and threatened crocodiles.
Pygmy or scrub mangrove forests are found in certain reaches of the Belizean mangroves. In these associations individual plants seldom surpass a height of 150 centimetres, except in circumstances where the mangroves grow on depressions filled with mangrove peat. Many of the shrub-trees are over forty years old. In these pygmy mangrove areas, nutrients appear to be limiting factors, although high salinity and high calcareous substrates may be instrumental. Chief disturbance factors are due to hurricanes and lightning strikes, both capable of causing substantial mangrove treefall. In many cases a pronounced gap is formed by lightning strikes, but such forest gaps actually engender higher sapling regrowth, due to elevated sunlight levels and slightly diminished salinity in the gaps.
Chief mangrove tree species found in this ecoregion are White Mangrove (Laguncularia racemosa), Red Mangrove (Rhizophora mangle), Black Mangrove (Avicennia germinans); the Button Mangrove (Conocarpus erectus) is a related tree associate. Red mangrove tends to occupy the more seaward niches, while Black mangrove tends to occupy the more upland niches. Other plant associates occurring in this ecoregion are Dragonsblood Tree (Pterocarpus officinalis), Guiana-chestnut (Pachira aquatica) and Golden Leatherfern (Acrostichum aureum).
In addition to hydrological stabilisation leading to overall permanence of the shallow sea bottom, the Belizean coastal zone mangrove roots and seagrass blades provides abundant nutrients and shelter for a gamut of juvenile marine organisms. A notable marine mammal found in the shallow seas offshore is the threatened West Indian Manatee (Trichecus manatus), who subsists on the rich Turtle Grass (Thalassia hemprichii) stands found on the shallow sea floor.
Wood borers are generally more damaging to the mangroves than leaf herbivores. The most damaging leaf herbivores to the mangrove foliage are Lepidoptera larvae. Other prominent herbivores present in the ecoregion include the gasteropod Littorina angulifera and the Mangrove Tree Crab, Aratus pisonii.
Many avian species from further north winter in the Belizean coast mangroves, which boast availability of freshwater inflow during the dry season. Example bird species within or visiting this ecoregion include the Yucatan Parrot (Amazona xantholora), , Yucatan Jay (Cyanocorax yucatanicus), Black Catbird (Dumetella glabrirostris) and the Great Kiskadee (Pitangus sulfuratus)
Upland fauna of the ecoregion include paca (Agouti paca), coatimundi (Nasua narica), Baird’s Tapir (Tapirus bairdii), with Black Howler Monkey (Alouatta caraya) occurring in the riverine mangroves in the Sarstoon-Temash National Park. The Mantled Howler Monkey (Alouatta palliata) can be observed along the mangrove fringes of the Monkey River mouth and other portions of this mangrove ecoregion.
Other aquatic reptiian species within the ecoregion include Morelet's Crocodile (Crocodylus moreletti), Green Turtle (Chelonia mydas), Hawksbill Sea Turtle (Eretmochelys imbricata), Loggerhead Sea Turtle (Caretta caretta), and Kemp’s Ridley (Lepidochelys kempi).
Preferred habitat of Caretta caretta individuals changes throughout the life cycle. Adult females go ashore to lay eggs and seem to prefer steeply sloped, high energy beaches. When hatchlings emerge from the nest, they head for the ocean. Young juveniles are typically found among drifting Sargassum mats in warm ocean currents. Older juveniles and adults are most often found in coastal waters and tend to prefer a rocky or muddy substrate over a sandy one. They may also be found near coral reefs and venturing into salt marshes, brackish lagoons, and the mouths of rivers.
Range depth: 0 to 61 m.
Habitat Regions: temperate ; tropical ; saltwater or marine
Aquatic Biomes: pelagic ; reef ; coastal ; brackish water
Other Habitat Features: estuarine
Habitat and Ecology
Comments: Open sea to more than 500 miles from shore, mostly over continental shelf, and in bays, estuaries, lagoons, creeks, and mouths of rivers; mainly warm temperate and subtropical regions not far from shorelines. Off North Carolina, loggerheads inhabited waters of 13-28 C (available range 5-32 C) (Coles and Musick 2000). Adults occupy various habitats, from turbid bays to clear waters of reefs. Subadults occur mainly in nearshore and estuarine waters. Hatchlings move directly to sea after hatching, often float in masses of sea plants (Sargassum); may remain associated with sargassum rafts perhaps for 3-5 years. In Chesapeake Bay, occurs mainly in deeper channels, usually at river mouths or in the open bay.
Nesting occurs usually on open sandy beaches above high-tide mark, seaward of well-developed dunes. Nests primarily on high-energy beaches on barrier strands adjacent to continental land masses in warm temperate and subtropical regions; steeply sloped beaches with gradually sloped offshore approaches are favored (CSTC 1990). Renesting generally occurs at the same beach or within a few km; generally returns to the same area in subsequent years if habitat remains suitable. Individuals sometimes change to different nesting beach within a single nesting season; has changed to sites up to several hundred km away (see Eckert et al. 1989). Maximum hatching success and hatchling size occur when sand moisture level is about 25%. In Florida, nesting on urban beaches was strongly correlated with the presence of tall objects (trees, buildings), which apparently shield the beach from city lights (Salmon et al. 1995). See Garmestani et al. (2000) for information on nest-site selection in southwestern Florida.
Niger Coastal Delta Habitat
The Niger Coastal Delta is an enormous classic distributary system located in West Africa, which stretches more than 300 kilometres wide and serves to capture most of the heavy silt load carried by the Niger River. The peak discharge at the mouth is around 21,800 cubic metres per second in mid-October. The Niger Delta coastal region is arguably the wettest place in Africa with an annual rainfall of over 4000 millimetres. Vertebrate species richness is relatively high in the Niger Delta, although vertebrate endemism is quite low. The Niger Delta swamp forests occupy the entire upper coastal delta. Historically the most important timber species of the inner delta was the Abura (Fleroya ledermannii), a Vulnerable swamp-loving West African tree, which has been reduced below populations viable for timber harvesting in the Niger Delta due to recent over-harvesting of this species as well as general habitat destruction of the delta due to the expanding human population here. Other plants prominent in the inner delta flood forest are: the Azobe tree (Lophira alata), the Okhuen tree (Ricinodendron heudelotii ), the Bitter Bark Tree (Sacoglottis gabonensis), the Rough-barked Flat-top Tree (Albizia adianthifolia), and Pycnanthus angolensis. Also present in its native range is the African Oil Palm (Elaeis guineensis)
Five threatened marine turtle species are found in the mangroves of the lower coastal delta: Leatherback Sea Turtle (Dermochelys coriacea, EN), Loggerhead Sea Turtle (Caretta caretta, EN), Olive Ridley Turtle (Lepidochelys olivacea, EN), Hawksbill Sea Turtle (Eretomychelys imbricata, CR), and Green Turtle (Chelonia mydas, EN).
There are a number of notable mammals present in the Niger Coastal Delta, including the Near Threatened Olive Colobus (Procolobus verus) that is restricted to coastal forests of West Africa and is found here in the inner coastal Niger Delta. Also found here is the restricted distribution Mona Monkey (Cercopithecus mona), a primate often associated with rivers. Also occurring here is the limited range Black Duiker (Cephalophus niger), a near-endemic to the Niger River Basin. In addition, the Endangered Chimpanzee (Pan troglodytes) is found in the Niger Delta. The near-endemic White-cheeked Guenon (Cercopithecus erythrogaster, VU) is found in the inner delta. The Critically Endangered Niger Delta Red Colubus (Procolobus pennantii ssp. epieni), which primate is endemic to the Niger Delta is also found in the inner delta.
Some of the reptiles found in the upper Niger Coastal Delta are the African Banded Snake (Chamaelycus fasciatus); the West African Dwarf Crocodile (Osteolaemus tetraspis, VU); the African Slender-snouted Crocodile (Mecistops cataphractus); the Benin Agama (Agama gracilimembris); the Owen's Chameleon (Chamaeleo oweni); the limited range Marsh Snake (Natriciteres fuliginoides); the rather widely distributed Black-line Green Snake (Hapsidophrys lineatus); Cross's Beaked Snake (Rhinotyphlops crossii), an endemic to the Niger Basin as a whole; Morquard's File Snake (Mehelya guirali); the Dull Purple-glossed Snake (Amblyodipsas unicolor); the Rhinoceros Viper (Bitis nasicornis). In addition several of the reptiles found in the outer delta are found within this inner delta area.
Other reptiles found in the outer NIger Coastal Delta are the Nile Crocodile (Crocodylus niloticus), African Softshell Turtle (Trionyx triunguis), African Rock Python (Python sebae), Boomslang Snake (Dispholidus typus), Cabinda Lidless Skink (Panaspis cabindae), Neon Blue Tailed Tree Lizard (Holaspis guentheri), Fischer's Dwarf Gecko (Lygodactylus fischeri), Richardson's Leaf-Toed Gecko (Hemidactylus richardsonii), Spotted Night Adder (Causus maculatus), Tholloni's African Water Snake (Grayia tholloni), Smith's African Water Snake (Grayia smythii), Small-eyed File Snake (Mehelya stenophthalmus), Western Forest File Snake (Mehelya poensis), Western Crowned Snake (Meizodon coronatus), Western Green Snake (Philothamnus irregularis), Variable Green Snake (Philothamnus heterodermus), Slender Burrowing Asp (Atractaspis aterrima), Forest Cobra (Naja melanoleuca), Rough-scaled Bush Viper (Atheris squamigera), and Nile Monitor (Varanus niloticus).
There are a limited number of amphibians in the inner Niger Coastal Delta including the Marble-legged Frog (Hylarana galamensis). At the extreme eastern edge of the upper coastal delta is a part of the lower Niger and Cross River watersheds that drains the Cross-Sanaka Bioko coastal forests, where the near endemic anuran Cameroon Slippery Frog (Conraua robusta) occurs.
Water temperature and chemistry ranges based on 67378 samples.
Depth range (m): 0 - 4250
Temperature range (°C): 2.225 - 28.845
Nitrate (umol/L): 0.018 - 29.138
Salinity (PPS): 32.229 - 38.627
Oxygen (ml/l): 2.773 - 7.183
Phosphate (umol/l): 0.025 - 1.916
Silicate (umol/l): 0.640 - 32.690
Depth range (m): 0 - 4250
Temperature range (°C): 2.225 - 28.845
Nitrate (umol/L): 0.018 - 29.138
Salinity (PPS): 32.229 - 38.627
Oxygen (ml/l): 2.773 - 7.183
Phosphate (umol/l): 0.025 - 1.916
Silicate (umol/l): 0.640 - 32.690
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
Warm and temperate marine waters.
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.
Migrates between nesting beaches and marine waters. At least some temperate zone nesters migrate to tropical waters after the nesting season (Dodd 1990). Females that nest on east coast of Florida migrate to the Gulf of Mexico and West Indies for non-nesting periods. Some individuals in the southeastern U.S. move north in spring (e.g., see Morreale and Standora, no date), south as fall approaches; others apparently remain in Florida waters year-round. Hatchlings from the southeastern U.S. apparently enter drift lines and ride currents to Europe and the Azores and back (Dodd 1990). MtDNA data confirm that juveniles occurring in pelagic habitats of the eastern Atlantic (Azores, Madeira) are derived from nesting populations in the southeastern United States and adjacent Yucatan Peninsula in Mexico (Bolten et al. 1998).
MtDNA data indicate that stranded individuals along foraging habitat in the northeastern United States from Massachusetts to Virginia originated from three demographically independent nesting areas: northeast Florida/North Carolina, southern Florida, and Quintana Roo (Mexico) (Rankin-Baransky et al. 2001).
MtDNA data indicate that young occurring along the coast of Baja California derive from nesting areas in Japan and Australia (B. Bowen et al. 1995, Proc. Natl. Acad. Sci. 92:3731-3734); evidently trans-Pacific migrations occur, encompassing several years.
In North Carolina, within a single year, most multiple-nesting females confined their nesting activities within 4.8 km (Webster and Cook 2001).
"In 1996, a loggerhead turtle called Adelita swam across 9,000 miles from Mexico to Japan, crossing the entire Pacific on her way. Wallace J. Nichols tracked this epic journey with a satellite tag. But Adelita herself had no such technology at her disposal. How did she steer a route across two oceans to find her destination?"
Read more at DISCOVER Blogs - Not Exactly Rocket Science: Turtles use the Earth’s magnetic field as a global GPS
Also see PBS Nature: Voyage of the Lonely Turtle
Loggerhead sea turtles are primarily carnivorous, but will also eat algae - Ascophyllum, Ulothrix, Urospora, Sargassum - and vascular plants - Cymodocea, Thalassia, Zostera - making them omnivorous. Their huge heads and massive, powerful jaws make them well-adapted to eating hard-shelled prey, such as horseshoe crabs (Limulus polyphemus), bivalves, barnacles, whelks, and conchs. However, Caretta caretta is a dietary generalist and also eats many other invertebrates, such as sponges, jellyfish, cephalopods, shrimp, insects, sea urchins, and fish and fish eggs, including Brecoortia species, Ceratoscopelus species, and Diodon species. There are slight variations in the diet of each life stage, but loggerhead sea turtles are generalists throughout life.
Animal Foods: fish; eggs; insects; mollusks; aquatic or marine worms; aquatic crustaceans; echinoderms; cnidarians; other marine invertebrates
Plant Foods: leaves; algae; macroalgae
Primary Diet: omnivore
Comments: Eats various marine invertebrates (crustaceans, mollusks, sponges, cnidaria, echinoderms, etc.), few plants; also fish (carrion or slow-moving species). Horseshoe crabs are preferred prey in Chesapeake Bay. Spider crabs and rock crabs were important prey at Long Island, New York (Copeia 1993:1176-1180). Adults forage primarily on the bottom (e.g., see Preen 1996, J. Herpetol. 30:94-96), also take jellyfish from surface. Young feed on prey (e.g., gastropods, fragments of crustaceans and sargassum) concentrated at the surface.
Caretta caretta has been called a "keystone species" because of its ecological impact. It feeds on large numbers of invertebrates, affecting their populations and allowing their broken shells to be used as a calcium source for other species. Also, a substantial portion of the eggs laid become food for predators. Finally, over 100 species from 13 phyla may live on the carapace of loggerheads, making it somewhat of a mobile reef.
Ecosystem Impact: creates habitat; keystone species
- barnacles (Cirripedia)
- skeleton shrimp (Caprellidea)
Most turtles are able to withdraw into their shell as a means of escaping a predator. No sea turtle is able to do this. Loggerhead sea turtles have their hard shell, their size, and their rough, scaly skin on the head and neck to protect them from predation. These defenses are usually sufficient for adults and larger juveniles, but these turtles are sometimes preyed on by sharks and killed by humans. Hatchlings and eggs have many predators and few defenses. Females try to disguise newly laid nests as much as possible, but they still suffer high predation rates. Raccoons (Procyon lotor) in U.S. can destroy up to 80% of nests on some beaches. Red foxes (Vulpes vulpes) in Australia may destroy 90 to 95% of nests. In some areas of the world human predation on nests is substantial. Hatchlings generally emerge from the nest at night to lessen chances of predation, but many are then taken by crabs, birds (gulls, frigate birds, vultures, crows, etc.), raccoons, canids (foxes, dogs, etc.), and carnivorous fish.
- bears (Ursus)
- red foxes (Vulpes vulpes)
- side-striped jackals (Canis adustus)
- raccoons (Procyon lotor)
- honey badgers (Mellivora capensis)
- humans (Homo sapiens)
- dogs (Canis lupus familiaris)
- frigatebirds (Fregata magnificens)
- crows Corvus
- carnivorous fish (Actinopterygii)
- ants (Formicidae)
- crabs (Decapoda)
- hogs (Sus)
- armadillos (Dasypodidae)
- sharks (Chondrichthyes)
- seagulls (Larus)
- rats (Rattus)
- small cats (Felis)
- skunks (Mephitis)
- opossums (Didelphis)
- bobcats and lynxes (Lynx)
Known prey organisms
aquatic or marine worms
This list may not be complete but is based on published studies.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 81 to >300
Comments: Represented by many occurrences throughout much of the range. Exact number not known, depends somewhat on partly subjective determination of EO-boundaries. There are at least two dozen major nesting areas worldwide (Dodd 1990).
100,000 - 1,000,000 individuals
Comments: Total population is perhaps 100,000 adult females (extrapolated from Dodd 1988). Aerial beach surveys indicated that about 14,150 females nested in the southeastern U.S. in 1983 (CSTC 1990). More recent estimates are similar. An estimated 50,000 to 70,000 clutches are deposited each year in the southeastern United States (Meylan et al. 1995). An estimated minimum of 2200-11,000 individuals occur in summer in waters off the northeastern U.S. (Shoop and Kenney 1992).
At least five different subpopulations have been identified in the western North Atlantic and Gulf of Mexico, with nesting abundance as follows (see NMFS 2002): (1) A Northern nesting subpopulation, occurring from North Carolina to northeast Florida at about 29 degrees N (about 7,500 nests in 1998); (2) a South Florida nesting subpopulation, occurring from 29 degrees N on the east coast to Sarasota on the west coast (approximately 83,400 nests in 1998); (3) a Florida Panhandle nesting subpopulation, occurring at Eglin Air Force Base and the beaches near Panama City, Florida (approximately 1,200 nests in 1998); (4) a Yucatan nesting subpopulation, occurring on the eastern Yucatan Peninsula, Mexico (approximately 1,000 nests in 1998); and (5) a Dry Tortugas nesting subpopulation, occurring in the islands of the Dry Tortugas, near Key West, Florida (approximately 200 nests per year) (see NMFS 2002).
Does not form schools but local concentrations may occur at sea or near nesting beaches.
Of every thousand hatchlings, only a few are believed to survive to adulthood; this is characteristic even of stable populations (Dodd 1988). In Georgia, annual survivorship of adult females was 0.81, juveniles 0.70-0.94; see Iverson (1991) for a compilation of survivorship data. Maximum reproductive life span 32 years (Frazer 1983).
Among a wide array of animals that eat loggerhead eggs, raccoons are the most important predators on eggs in the southeastern U.S.; on some beaches they have been responsible for more than 90% of nest mortality (Dodd 1988). Organisms attached to the shell are not known to pose a significant threat.
Cold stunning in estuaries (e.g., Long Island Sound) sometimes can result in significant mortality. See Witherington and Ehrhart (1989) for information on cold stunning in Florida.
Data on heavy metal concentrations in eggs support the hypothesis that the western Atlantic population is composed of demes (Stoneburner et al. 1980).
Life History and Behavior
Communication in Caretta caretta has not been well-studied. Courtship behavior seems to largely depend on visual and tactile cues, but it has been suggested that glandular odors (especially Rathke's gland secretions) may help bring the sexes together.
Perception, however, is highly developed. As soon as hatchlings emerge from their nests (usually at night), they begin analyzing their environment to determine which direction they should go towards the ocean. It is believed that a major clue is the light on the horizon. Hatchlings orient towards the brightest light, which, historically, is the moon or star light over the ocean. They may also perceive the incline of the beach and orient towards a lower elevation. Once in the water, hatchlings use chemical and magnetic cues to orient themselves and navigate their way to the currents in which they will spend the next 10 or so years of their lives.
During the juvenile and adult years it is likely that loggerheads use chemical and magnetic cues to orient themselves during their migrations. It has been demonstrated that C. caretta uses on-site cues, not memory of past movement, in orientation and is therefore capable of map-based navigation.
Food is typically located either visually or by smell.
Communication Channels: visual ; tactile ; chemical
Other Communication Modes: pheromones
Perception Channels: visual ; polarized light ; tactile ; vibrations ; chemical ; magnetic
Carnivorous, feeding largely on marine invertebrates, crabs, jellyfish, sponges, and occasionally fish. Young are largely pelagic, while adults stay closer to shore. Undergoes extensive migrations from and to nesting beaches, feeding grounds and seasonally to escape low temperatures. Nests sometimes on fairly disturbed beaches. A nest probably belonging to this species was found on a busy public beach in Alexandria in the 1970s (Baha El Din unpub. obs.). Many nests and nesting attempts detected by Clarke et al. (2000) were in fairly disturbed stretches of beach. Nesting in the eastern Mediterranean takes place between June and September (Clarke et al. 2000). Sexual maturity reached between 10 and 15 years (Schleich et al. 1996).
Comments: May bury in bottom mud during cold periods in some areas (e.g., Port Canaveral ship channel off eastern Florida, Gulf of California) (Dodd 1988).
Like many turtles, Caretta caretta has temperature-dependent sex determination (TSD). The sex of hatchlings is determined by egg temperature during the middle third of incubation. The pivotal temperature - the temperature at which an 50:50 ratio of males:females is produced - varies from location to location around the world. For example, the pivotal temperature in South Africa is 29.7 ºC , but in Australia the pivotal temperature is 28.2 ºC. Generally, the pivotal temperature is between 28 and 30 ºC. Temperatures of 24 to 26 ºC tend to produce all males and temperatures of 32 to 34 ºC tend to produce all females. Eggs are not viable outside the extremes of these ranges.
The speed of embryonic development within the egg depends on the temperature within the nest. This temperature can be affected by sun, shade, rain, heat generated within the nest, and an egg's position in the nest. At cool temperatures, around 25 ºC, development to hatching can take 65 to 70 days, but at warmer temperatures, around 35 ºC, development usually takes around 45 days.
When loggerheads are juveniles the differences between the sexes begin to emerge. Males produce increasing levels of testosterone as they approach maturity, which triggers tail growth, plastron softening, and the growth and curvature of a nail on each forelimb. Females produce estrogen and small amounts of testosterone, but externally just grow larger. Age at maturity is variable. Mature size is attained between age 10 and 30; captives are predicted to mature in 16 to 17 years. Reproductve life span (after reaching maturity) is estimated at about 32 years.
Development - Life Cycle: temperature sex determination
Not much is known about the lifespan of Caretta caretta. Is is estimated that they live 30 to 62 years in the wild, but data is insufficient for lifespan in captivity as well as longest known lifespans in the wild and in captivity. In Australia is has been predicted that the annual survival rate is 92% for immature individuals and 88% for adults.
Status: captivity: 33 (high) years.
Status: wild: 30 to 62 years.
Status: captivity: 33.0 years.
Lifespan, longevity, and ageing
Just before the nesting season, male loggerhead sea turtles migrate to mating grounds, which are usually located offshore from nesting beaches. They wait for females to begin courtship and mating. A male will circle a female, then approach her and bite her neck or shoulder. He will then attempt to mount her and, if she accepts him, they will mate. If a female does not accept the male she covers her cloaca and swims to the bottom, but a persistent male may wait until she needs air and make another attempt. Males use the long, curved claws on their forelimbs to hold on because mating may last for hours and other males often ram and bite the mating male, attempting to dislodge him. If a male is dislodged, another may quickly replace him.
During the nesting season a female may lay several clutches, and will re-mate each time. In some cases, she may mate several times between clutches and so a single clutch may have sperm contributed by several males.
Mating System: polygynandrous (promiscuous)
Peak mating season for Caretta caretta occurs in the early summer months. During this time, males remain in the waters offshore of the nesting beach, while females alternate between mating in the water, nesting on land, and feeding in estuaries and reefs. A female will nest every 12 to 17 days, or 2 to 5 times, during the breeding season. For each nest she must drag herself onto land, where she is in much greater danger of predation, and excavate a nest. Into this nest she lays 110 to 130 round eggs. The eggs incubate for 45 to 80 days, depending on temperature. Loggerhead sea turtles reach sexual maturity at carapace lengths longer than 90 cm, which can occur between 10 and 30 years of age.
Breeding interval: Loggerhead sea turtles breed, on average, every 12 to 17 days during the breeding season. Females will not breed again for another 2 to 4, but possibly up to 9 years.
Breeding season: Breeding may occur year-round, but it peaks between May and July.
Range number of offspring: 23 to 198.
Average number of offspring: 110-130.
Range gestation period: 46 to 80 days.
Range age at sexual or reproductive maturity (female): 12 to 35 years.
Range age at sexual or reproductive maturity (male): 12 to 35 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; oviparous
Average number of offspring: 115.
Parental energy investment in loggerhead sea turtles is largely pre-ovipositional, there is no parental care of young. Females provide nutrition in the form of yolk which is used by embryos for growth and development; residual yolk can probably support a hatchling for several days or weeks. Females also expend considerable energy when migrating to nesting beaches and in the ovipositional (nesting/ egg laying) process. Male investment is largely during courtship and mating, and in sperm production.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female)
In the southeastern U.S., mating occurs late March-early June. Lays 1-9 clutches (mostly 2-6) of about 45-200 eggs (average 120) at intervals of about 2 weeks, mostly every 2-3 years. Nests mainly at night, often at high tide. In the U.S., nests late April-early September, peak in June. Eggs hatch in about 7-11 weeks (generally 8-9 weeks in the southeastern U.S.). Egg mortality may result from predation, beach erosion, invasion of clutches by plant roots, crushing by off-road vehicles, or flooding by sea water overwash or excessive rainfall. Sex of hatchlings is affected by incubation temperature, with warmer temperatures resulting in a preponderance of females and cooler temperatures producing mainly or only males. Hatchlings emerge from nest a few days after hatching, typically during darkness. Sex ratio of hatchlings and immatures in Atlantic coastal waters of U.S. is strongly biased toward females (Wibbels et al. 1991, Mrosovsky and Provancha 1992). Females are sexually mature at an average age of about 15-30 years in the southeastern U.S. (but see Bjorndal and Bolten  for information on juvenile growth rates that suggests earlier age of maturity; see also Klinger and Misick, Copeia 1995:204-209, and Zug et al., Copeia 1995:484-487, for growth rate and age-at-maturity information). Females are reproductively active over a period of about 30 years (CSTC 1990). Nesting density reaches nearly 450 nests/km in some areas of Florida (Dodd 1992).
Molecular Biology and Genetics
Barcode data: Caretta caretta
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Caretta caretta
Public Records: 7
Specimens with Barcodes: 18
Species With Barcodes: 1
Caretta caretta, like all sea turtle species, is in decline. The greatest causes of decline world-wide is probably incidental capture in fishing gear such as long lines, gill nets, shrimp trawls, and direct exploitation of adult turtles and eggs for human food. Though in sharp decline in many parts of its range, and locally along North American coasts, loggerhead sea turtles are currently the most common and least-threatened marine turtle in North American waters. They are listed as threatened under the U.S. Endangered Species Act.
Other important causes of decline include beachfront development, human disturbance of nesting females, pesticides, petroleum products (oil spills), and other ocean pollutants, human-influenced increases in nest predators such as raccoons, collisions with watercraft, and offshore and channel dredging. Artificial lighting near beaches can confuse emerging hatchlings, causing them to move away from the ocean and into hazardous urban areas. If predictions about global warming are realized, increased storms and rising sea levels could damage or destroy nesting areas and nests, and temperature changes could skew sex ratios.
The United States has taken several measures to reduce bycatch of loggerhead sea turtles. Turtle exclusion devices (TEDs) are required in commercial fishing and shrimping nets. There have been other gear modifications, changes in practice, and area closures in fishing that have reduced bycatch. Also, other countries may harvest shrimp in a way that puts loggerhead sea turtles in danger and the U.S. has put an embargo on these shrimp. Despite these measures being taken, the numbers of loggerhead sea turtles in U.S. waters is still declining.
US Federal List: threatened
CITES: appendix i
State of Michigan List: no special status
IUCN Red List of Threatened Species: endangered
IUCN Red List Assessment
Red List Category
Red List Criteria
- Needs updating
- 1994Vulnerable(Groombridge 1994)
- 1990Vulnerable(IUCN 1990)
- 1988Vulnerable(IUCN Conservation Monitoring Centre 1988)
- 1986Vulnerable(IUCN Conservation Monitoring Centre 1986)
National NatureServe Conservation Status
Rounded National Status Rank: N3B - Vulnerable
NatureServe Conservation Status
Rounded Global Status Rank: G3 - Vulnerable
Reasons: Wide distribution and not uncommon in warm oceans and seas; many nesting sites are protected, though perhaps not adequately; subject to many threats that land conservation alone cannot solve.
Intrinsic Vulnerability: Highly vulnerable
Environmental Specificity: Very narrow to narrow.
Date Listed: 10/24/2011
Lead Region: Southeast Region (Region 4)
Where Listed: North Pacific Ocean DPS
Date Listed: 10/24/2011
Lead Region: Foreign (Region 10)
Where Listed: Mediterranean Sea DPS
Date Listed: 10/24/2011
Lead Region: Foreign (Region 10)
Where Listed: North Indian Ocean DPS
Date Listed: 10/24/2011
Lead Region: Foreign (Region 10)
Where Listed: Northeast Atlantic Ocean DPS
Date Listed: 10/24/2011
Lead Region: Foreign (Region 10)
Where Listed: South Pacific Ocean DPS
Date Listed: 10/24/2011
Lead Region: Southeast Region (Region 4)
Where Listed: Northwest Atlantic DPS
Date Listed: 10/24/2011
Lead Region: Foreign (Region 10)
Where Listed: South Atlantic Ocean DPS
Date Listed: 10/24/2011
Lead Region: Foreign (Region 10)
Where Listed: Southeast Indian Ocean DPS
Date Listed: 10/24/2011
Lead Region: Foreign (Region 10)
Where Listed: Southwest Indian Ocean DPS
For most current information and documents related to the conservation status and management of Caretta caretta, see its USFWS Species Profile
Status in Egypt
Uncommon, declining but still widespread. Significant numbers are probably caught by commercial fishing vessels, whence they reach fish markets in Egyptian coastal cities. Loss of nesting beaches is an important problem particularly in North Sinai. However, Kasparek (1993) described the breeding population on the western Mediterranean coast of Egypt as "negligible." The same term can be applied to the small North Sinai population. Thus, the major conservation issue facing this and other marine turtles in Egypt is the threat by commercial marine fisheries.
Global Short Term Trend: Decline of 10-30%
Comments: Although natural population fluctuations may occur, numbers appear to be declining in some areas because of habitat destruction and incidental take. Overall, the nesting population in the southeastern U.S. is believed to be declining (CSTC 1990, Taylor 1992).
The northern subpopulation in the western North Atlantic has declined dramatically over the past 20 years. Nesting trends at Cape Island, South Carolina, and Little Cumberland Island, Georgia, nesting beaches that have been consistently surveyed since the early 1970s: from 1973 to 1995, nesting at Cape Island declined on average 3.2 percent per year, and from 1964 to 1995, Little Cumberland nesting activity declined at 2.6 percent per year (see NMFS 2002, Jenkins 2002).
Degree of Threat: Very high - high
Comments: Threatened through direct exploitation for food (including eggs) and curio materials, incidental take (chiefly by drowning in shrimp trawls), and by habitat degradation, including beach development, beachfront lighting (Peters and Verhoeven 1994, Salmon and Witherington 1995), ocean pollution (including marine debris, which may be ingested), and dredging (direct kills and injuries). Beach armoring, including sea walls, rock revetments, riprap, sandbag installation, groins, and jetties, can result in loss of nesting beaches due to accelerated erosion, prevention of natural beach and dune accretion, and interference with females attempting to reach suitable nesting sites. Beach cleaning operations can destroy nests or produce tire ruts that inhabitat movement of hatchlings to sea. The effect of beach restoration may depend on sand type used and subsequent management. Additional threats include predation and/or trampling of eggs and young by raccoons and feral mammals, trampling/crushing of eggs or young by vehicles or human pedestrians, deaths caused by collisions with boats (e.g., in southeastern and southern Florida and shallow coastal bays of the Gulf of Mexico) and intentional attacks by humans (fishermen) (Mitchell 1991). Long-term threats include sea level rise which, coupled with inland urbanization, may reduce available nesting beaches. Since sexual differentiation depends on incubation temperature, there is concern that global warming may result in an imbalance in the sex ratio (Mrosovsky and Provancha 1989). Annual mortality due to drowning in shrimp nets has been estimated at 5000-50,000 in the southeastern U.S.; an additional 550-5500 may die each year from other human activities (CSTC 1990). The fall bottom fishery and black drum fishery may be having adverse effects on loggerheads that use Chesapeake Bay (Mitchell 1991). Susceptible to entanglement and drowning in pound net hedging in Chesapeake Bay (Lutcavage and Musick 1985). In Georgia, predation by the imported fire ant may be a serious threat to eggs and hatchlings (Moulis 1997). See USFWS (1998) for detailed information on certain threats, including beach erosion, beach armoring, beach nourishment, artificial lighting, beach cleaning, increased human presence, recreational beach equipment, exotic dune and beach vegetation, nest loss to abiotic factors, predation, and poaching.
Peckham et al. (2007) found that small-scale fisheries result in significant bycatch mortality of loggerheads, rivaling that of oceanwide industrial-scale fisheries. To address this serious threat, the authors advocate the localization of coastal high use areas and mitigation of bycatch in partnership with small-scale fishers.
Restoration Potential: Because so little is known loggerhead population dynamics and demography, it is difficult to assess restoration potential. However, most authors, in discussing conservation strategies, seem optimistic about the loggerhead's recovery if the ongoing population declines can be halted. Turtle excluder devices (TEDs) appear to be effective in reducing mortality associated with the shrimp fishery, improving the outlook for population recovery (Crowder et al. 1995)
Preserve Selection and Design Considerations: It is impossible to protect the loggerhead throughout its life cycle due to its expansive range and wandering years at sea. However, nesting beaches can and should be protected. These beaches should be undeveloped, unlighted, virtually unused by humans, and fishing, especially shrimp trawling, should not be allowed near them, especially in the breeding season. These beaches should be carefully managed for the benefit of the loggerhead.
Management Requirements: Worldwide public awareness of plight of sea turtles needs to be improved. Frazer (1992) emphasized the primary need for clean and productive marine and coastal environments; installation of turtle excluder devices in shrimp trawl nets and use of low pressure sodium lighting on beaches were suggested as appropriate sea turtle conservation technologies, whereas headstarting, captive breeding, and hatcheries were regarded as ineffective at best.
The immediate management goal should be to stop the population decline. Although natural mortality contributes to the decline, it is not easy to manipulate. Efforts should be focused on protecting nesting habitat, nesting females, and nests, and on lowering mortality caused by humans. Specific beneficial management activities related to nesting include relocating nests threatened by erosion, restricting beach armoring, closely monitoring beach nourishment, enforcing lighting ordinances, regulating off road vehicles, and protecting nests from pedestrian traffic and beach cleaning equipment by either moving eggs to safer places or marking their presence. Disturbance of nesting females and harvest of adults and eggs should be prevented.
Lights near beaches may disorient hatchlings (Peters and Verhoeven 1994) and discourage nesting; beach lighting restrictions on nesting baches should include the entire period of darkness (Witherington et al. 1990). If lighting cannot be eliminated, low pressure sodium vapor lights may be the least disruptive to nesting turtles (Witherington 1992). Adding a low light barrier (simulating a dune or dense vegetation) improved hatchling orientation accuracy on urban beach segments exposed to lights in Florida (Salmon et al. 1995).
In addition to protection and suitable management of nesting habitat, reduction in trawl-related mortality (associated with shrimping), through the use of turtle excluder devices (TEDs, required for offshore shrimpers as of July 1989), seasonal fisheries closures, and reduced tow times, are regarded as primary management needs (CSTC 1990, USFWS 1990, Crowder et al. 1994, Lewison et al. 2003). Use of TEDs by shrimp trawlers theoretically could reduce the capture of sea turtles to 3% of the rate without the TED.
TEDs are designed to be installed in shrimp-trawl gear with the purpose of releasing sea turtles and other large objects from nets without releasing shrimp. By November of 1989, six TEDs had been approved by the National Marine Fisheries Service (NMFS), meaning that they are able to exclude at least 97% of the sea turtles otherwise captured and retained in a control trawl without a TED. Use of TEDs should be mandated and regulated from Cape Hatteras to the Texas-Mexican border, as well as all other areas where sea turtles are known to be caught in shrimp trawls. Tow-time limits can reduce the average rate of mortality of sea turtles to a negligible point as tow time is reduced to 60 minutes or less. This can be better than TEDs for areas with a lot of debris. The recommended tow-times are vary seasonally, specifying 40 minutes in the summer and 60 minutes in the winter. Limited time/area closures for turtle "hot spots" should be considered. See NMFS (1993) for recent shrimp trawling regulations for an area off the coast of North Carolina (allow tow-time limits as an interim alternative to the use of turtle excluder devices). See NMFS (Federal Register, 19 December 1996, pp. 66933-66947) for recent amendments to regulations pertaining to the use of turtle excluder devices along the Gulf and Atlantic coasts of the southeastern U.S. Population models indicate that good compliance with regulations requiring TEDs year-round in all waters of the southeastern United States could allow the population to increase much faster than expected under the "seasonal offshore" regulations (Crowder et al. 1994).
Efforts should be made to avoid sea turtle entrainment in power plant water intakes. Additionally, the use of explosives to remove oil rigs should be prohibited until more is known about its affect on loggerheads.
Effort is needed in informing and educating the public on minimizing disturbance to nesting turtles, protecting nests, and rescuing disorientated hatchlings. Mitchell (1991) noted the importance of public education in reducing mortality caused by humans.
In some areas, predator control may be needed to combat raccoons and other predators whose coastal populations are abnormally high due to food resources being augmented by human refuse. Wire-mesh predator (e.g., raccoon) exclosures around nests have been used in some areas (e.g., Canaveral National Seashore) to enhance reproductive success (1994 End. Sp. Tech. Bull. 19(2):16). However, in Florida, Mroziak et al. (2000) found that predator exclosure cages failed to protect nests and may have attracted them; the authors concluded that reducing predator populations is more effective than using cages to protect nests. See Matthews and Moseley (1990) for examples of interagency cooperation in protecting nesting areas and reducing egg loss to predators. Elimination/control of feral livestock on barrier islands may allow increased production of hatchlings (Shoop et al. 1985).
Public purchase of undeveloped beaches may be effective in providing prolonged protection of turtles and their habitat. Available lands should be protected before they are lost to development interests. In Florida, 16 km of undeveloped beach from Melbourne Beach to Wabasso Beach is available and should be protected as this is a tremendously important nesting area from a global perspective. Also, the establishment of a marine park at Rancho Nuevo in Mexico would be beneficial.
Headstarting and captive breeding should remain research tools but should not be used as substitutes for other conservation measures. Eggs relocated to polystyrene incubators have higher hatching success than do eggs in undisturbed nests or eggs relocated to other beach sites (Wyneken et al. 1988). See McGehee (1990) for information on egg incubation procedures. See Mrosovsky and Benabib (1990) for an evaluation of methods for sexing hatchlings.
See Dodd (1992) for protection recommendations for Florida.
See recovery plan: Marine Turtle Recovery Team (1984). See also "Recovery plan for U.S. Pacific populations of the loggerhead turtle (CARETTA CARETTA)" (NMFS 1998). See USFWS (1998) for detailed information on management and recovery, especially for populations in Florida.
See Dodd (1988) for further discussion of management strategies.
Management Research Needs: An enlargement of tagging programs and the creation of new ones, paying special attention to the problem of tag loss, will help in gaining much-needed population data. The ecology and movements of hatchlings and young need to be investigated.
Research on the effects and prevalence of cold stunning should be carried out. Improved resuscitation techniques of comatose turtles should be developed.
Accurate postmortem techniques need to be developed to determine the role of plastic ingestion on turtle deaths, and documentation is needed of the extent of the problem. Also, information is needed on the effects of petroleum ingestion and fouling.
Detailed examination of the potential of shrimping in fishing zones and times of the year when damage to turtle populations would be minimal without TED or tow- time restrictions is needed. Improved TEDs should be developed and new alternatives explored. The effectiveness of tow-time limitations needs to be documented. More information is needed on the impact of groundfish trawling, set-net and long-line fishing, gill nets, and pound-net fishing.
The complex effects of artificial protection of early life stages of sea turtles needs to be determined.
Global Protection: Many to very many (13 to >40) occurrences appropriately protected and managed
Comments: Many nesting beaches worldwide are designated for protection, although poaching occurs. Listed threatened by USFWS (F.R. 07-28-78). Required TED use (see "GPROTNEED") in some areas (southeastern United States). See NMFS (2001, Federal Register 66:50148-50159) or Jenkins (2002) for a review of proposed new TED regulations.
Needs: Restrict human presence on and degradation of nesting beaches and adjacent land and water. Use of TEDs (turtle excluder devices) needs to be mandatory on shrimping vessels from all countries. Beachfront lighting should be banned or converted to turtle-insensitive wavelengths. Take immediate steps to reduce global warming and sea level rise.
See "Recovery plan for U.S. Pacific populations of the loggerhead turtle (CARETTA CARETTA)" (draft document was available from National Marine Fisheries Service, Silver Spring, Maryland, and U.S. Fish and Wildlife Service, Portland, Oregon, in 1995).
Relevance to Humans and Ecosystems
There are no known adverse effects of Caretta caretta on humans.
Caretta caretta is beneficial to humans in many ways. Sea turtles are an attraction for ecotourism and popular with people wanting to snorkel or dive with these animals, as well as for those wanting to watch the nesting process. Loggerhead sea turtles are the most common sea turtle in U.S. waters and therefore most sea turtle research is carried out on this species. Also, in many countries, especially in Central and South America, Africa, Asia, and the Mediterranean, these turtles and their eggs are exploited for food.
Positive Impacts: food ; body parts are source of valuable material; ecotourism ; research and education
Loggerhead sea turtle
The loggerhead sea turtle (Caretta caretta), or loggerhead, is an oceanic turtle distributed throughout the world. It is a marine reptile, belonging to the family Cheloniidae. The average loggerhead measures around 90 cm (35 in) long when fully grown, although larger specimens of up to 280 cm (110 in) have been discovered. The adult loggerhead sea turtle weighs approximately 135 kg (298 lb), with the largest specimens weighing in at more than 450 kg (1,000 lb). The skin ranges from yellow to brown in color, and the shell is typically reddish-brown. No external differences in gender are seen until the turtle becomes an adult, the most obvious difference being the adult males have thicker tails and shorter plastrons than the females.
The loggerhead sea turtle is found in the Atlantic, Pacific, and Indian Oceans, as well as the Mediterranean Sea. It spends most of its life in saltwater and estuarine habitats, with females briefly coming ashore to lay eggs. The loggerhead sea turtle has a low reproductive rate; females lay an average of four egg clutches and then become quiescent, producing no eggs for two to three years. The loggerhead reaches sexual maturity within 17–33 years and has a lifespan of 47–67 years.
The loggerhead sea turtle is omnivorous, feeding mainly on bottom-dwelling invertebrates. Its large and powerful jaws serve as an effective tool for dismantling its prey. Young loggerheads are exploited by numerous predators; the eggs are especially vulnerable to terrestrial organisms. Once the turtles reach adulthood, their formidable size limits predation to large marine animals, such as sharks.
Loggerheads are considered an endangered species and are protected by the International Union for the Conservation of Nature. Untended fishing gear is responsible for many loggerhead deaths. Turtles may also suffocate if they are trapped in fishing trawls. Turtle excluder devices have been implemented in efforts to reduce mortality by providing an escape route for the turtles. Loss of suitable nesting beaches and the introduction of exotic predators have also taken a toll on loggerhead populations. Efforts to restore their numbers will require international cooperation, since the turtles roam vast areas of ocean and critical nesting beaches are scattered across several countries.
- 1 Description
- 2 Distribution
- 3 Habitat
- 4 Ecology and behavior
- 5 Life history
- 6 Taxonomy
- 7 Conservation
- 8 Symbols
- 9 See also
- 10 References
- 11 Further reading
- 12 External links
The loggerhead sea turtle is the world's largest hard-shelled turtle. Adults have an average weight range of 80 to 200 kg (180 to 440 lb) and a length range of 70 to 95 cm (28 to 37 in). The maximum reported weight is 545 kg (1,202 lb) and the maximum carapace length is 213 cm (84 in). The head and carapace (upper shell) range from a yellow-orange to a reddish-brown, while the plastron (underside) is typically pale yellow. The turtle's neck and sides are brown on the tops and yellow on the sides and bottom.
The turtle's shell is divided into two sections: carapace and plastron. The carapace is further divided into large plates, or scutes. Typically, 11 or 12 pairs of marginal scutes rim the carapace. Five vertebral scutes run down the carapace's midline, while five pairs of costal scutes border them. The nuchal scute is located at the base of the head. The carapace connects to the plastron by three pairs of inframarginal scutes forming the bridge of the shell. The plastron features paired gular, humeral, pectoral, abdominal, femoral, and anal scutes. The shell serves as external armor, although loggerhead sea turtles cannot retract their heads or flippers into their shells.
Sexual dimorphism of the loggerhead sea turtle is only apparent in adults. Adult males have longer tails and claws than females. The males' plastrons are shorter than the females', presumably to accommodate the males' larger tails. The carapaces of males are wider and less domed than the females', and males typically have wider heads than females. The sex of juveniles and subadults cannot be determined through external anatomy, but can be observed through dissection, laparoscopy (an operation performed on the abdomen), histological examination (cell anatomy), and radioimmunological assays (immune study dealing with radiolabeling).
Lachrymal glands located behind each eye allow the loggerhead to maintain osmotic balance by eliminating the excess salt obtained from ingesting ocean water. On land, the excretion of excess salt gives the false impression that the turtle is crying.
The loggerhead sea turtle has a cosmopolitan distribution, nesting over the broadest geographical range of any sea turtle. It inhabits the Atlantic, Indian, and Pacific Oceans and the Mediterranean Sea.
In the Atlantic Ocean, the greatest concentration of loggerheads is along the southeastern coast of North America and in the Gulf of Mexico. Very few loggerheads are found along the European and African coastlines. Florida is the most popular nesting site, with more than 67,000 nests built per year. Nesting extends as far north as Virginia, as far south as Brazil, and as far east as the Cape Verde Islands. The Cape Verde Islands are the only significant nesting site on the eastern side of the Atlantic. Loggerheads found in the Atlantic Ocean feed from Canada to Brazil.
In the Indian Ocean, loggerheads feed along the coastlines of Africa, the Arabian Peninsula, and in the Arabian Sea. Along the African coastline, loggerheads nest from Mozambique's Bazaruto Archipelago to South Africa's St Lucia estuary. The largest Indian Ocean nesting site is Oman, on the Arabian Peninsula, which hosts around 15,000 nests, giving it the second largest nesting population of loggerheads in the world. Western Australia is another notable nesting area, with 1,000–2,000 nests per year.
Pacific loggerheads live in temperate to tropical regions. They forage in the East China Sea, the southwestern Pacific, and along the Baja California Peninsula. Eastern Australia and Japan are the major nesting areas, with the Great Barrier Reef deemed an important nesting area. Pacific loggerheads occasionally nest in Vanuatu and Tokelau. Yakushima Island is the most important site, with three nesting grounds visited by 40% of all nearby loggerheads. After nesting, females often find homes in the East China Sea, while the Kuroshio Current Extension's Bifurcation region provides important juvenile foraging areas. Eastern Pacific populations are concentrated off the coast of Baja California, where upwelling provides rich feeding grounds for juvenile turtles and subadults. Nesting sites along the eastern Pacific Basin are rare. mtDNA sequence polymorphism analysis and tracking studies suggest 95% of the population along the coast of the Americas hatch on the Japanese Islands in the western Pacific. The turtles are transported by the prevailing currents across the full length of the northern Pacific, one of the longest migration routes of any marine animal. The return journey to the natal beaches in Japan has been long suspected, although the trip would cross unproductive clear water with few feeding opportunities. Evidence of a return journey came from an adult female loggerhead named Adelita, which in 1996, equipped with a satellite tracking device, made the 14500-km (9000-mi) trip from Mexico across the Pacific. Adelita was the first animal of any kind ever tracked across an ocean basin.
The Mediterranean Sea is a nursery for juveniles, as well as a common place for adults in the spring and summer months. Almost 45% of the Mediterranean juvenile population has migrated from the Atlantic. Loggerheads feed in the Alboran Sea and the Adriatic Sea. Greece is the most popular nesting site along the Mediterranean, with more than 3,000 nests per year. Because of this, Greek authorities do not allow planes to take off or land at night in Zakynthos due to the nesting turtles. In addition to the Greek coast, the coastlines of Cyprus and Turkey are also common nesting sites.
One record of this turtle was made in Ireland washed ashore on Ballyhealy Beach in Co. Wexford.
Loggerhead sea turtles spend most of their lives in the open ocean and in shallow coastal waters. They rarely come ashore, except for the females' brief visits to construct nests and deposit eggs. Hatchling loggerhead turtles live in floating mats of Sargassum algae. Adults and juveniles live along the continental shelf, as well as in shallow coastal estuaries. In the northwestern Atlantic Ocean, age plays a factor in habitat preference. Juveniles are more frequently found in shallow estuarine habitats with limited ocean access compared to non-nesting adults. Loggerheads occupy waters with surface temperatures ranging from 13.3-28.0°C (56-82°F) during non-nesting season. Temperatures from 27-28°C are most suitable for nesting females.
Juvenile loggerheads share the Sargassum habitat with a variety of other organisms. The mats of Sargassum contain as many as 100 different species of animals on which the juveniles feed. Some of the prey, such as ants, flies, aphids, leafhoppers, and beetles, are carried by the wind to these areas. Endemic prey of the mats include barnacles, small crab larvae, fish eggs, and hydrozoan colonies. Marine mammals and commercial fish, such as tuna, dolphin fish, and amberjacks, also inhabit the mats.
Ecology and behavior
Loggerhead sea turtles observed in captivity and in the wild are most active during the day. In captivity, the loggerheads' daily activities are divided between swimming and resting on the bottom. While resting, they spread their forelimbs to about midstroke swimming position. They remain motionless with eyes open or half-shut and are easily alerted during this state. At night, captives sleep in the same position with their eyes tightly shut, and are slow to react. Loggerheads spend up to 85% of their day submerged, with males being the more active divers than females. The average duration of dives is 15–30 min, but they can stay submerged for up to four hours. Juvenile loggerheads and adults differ in their swimming methods. A juveniles keeps its forelimbs pressed to the side of its carapace, and propels itself by kicking with its hind limbs. As the juvenile matures, its swimming method is progressively replaced with the adult's alternating-limb method. They depend entirely on this method of swimming by one year old.
Water temperature affects the sea turtle's metabolic rate. Lethargy is induced at temperatures between 13 and 15°C (55 and 59°F). The loggerhead takes on a floating, cold-stunned posture when temperatures drop to around 10°C. However, younger loggerheads are more resistant to cold and do not become stunned until temperatures drop below 9°C. The loggerheads' migration helps to prevent instances of cold-stunning. Higher water temperatures cause an increase in metabolism and heart rate. A loggerhead's body temperature increases in warmer waters more quickly than it decreases in colder water; their critical thermal maximum is currently unknown.
Female-female aggression, which is fairly rare in other marine vertebrates, is common among loggerheads. Ritualized aggression escalates from passive threat displays to combat. This conflict primarily occurs over access to feeding grounds. Escalation typically follows four steps. First, initial contact is stimulated by visual or tactile cues. Second, confrontation occurs, beginning with passive confrontations characterized by wide head-tail circling. They begin aggressive confrontation when one turtle ceases to circle and directly faces the other. Third, sparring occurs with turtles snapping at each other’s jaws. The final stage, separation, is either mutual, with both turtles swimming away in opposite directions, or involves chasing one out of the immediate vicinity. Escalation is determined by several factors, including hormone levels, energy expenditure, expected outcome, and importance of location. At all stages, an upright tail shows willingness to escalate, while a curled tail shows willingness to submit. Because higher aggression is metabolically costly and potentially debilitating, contact is much more likely to escalate when the conflict is over access to good foraging grounds. Further aggression has also been reported in captive loggerheads. The turtles are seemingly territorial, and will fight with other loggerheads and sea turtles of different species.
The loggerhead sea turtle is omnivorous, feeding mainly on bottom-dwelling invertebrates, such as gastropods, bivalves, and decapods. It has a greater list of known prey than any other sea turtle. Other food items include sponges, corals, sea pens, polychaete worms, sea anemones, cephalopods, barnacles, brachiopods, isopods, insects, bryozoans, sea urchins, sand dollars, sea cucumbers, starfish, fish (eggs, juveniles, and adults), hatchling turtles (including members of its own species), algae, and vascular plants. During migration through the open sea, loggerheads eat jellyfish, floating molluscs, floating egg clusters, squid, and flying fish.
Loggerheads crush prey with their large and powerful jaws. Projecting scale points on the anterior margin of the forelimbs allow manipulation of the food. These points can be used as "pseudo-claws" to tear large pieces of food in the loggerhead's mouth. The loggerhead will turn its neck sideways to consume the torn food on the scale points. Inward-pointing, mucus-covered papillae found in the fore region of the loggerhead's esophagus filter out foreign bodies, such as fish hooks. The next region of the esophagus is not papillated, with numerous mucosal folds. The digestion rate in loggerheads is temperature-dependent; it increases as temperature increases.
Loggerheads have numerous predators, especially early in their lives. Egg and nestling predators include ghost crabs, oligochaete worms, beetles, fly larvae, ants, parasitoid wasp larvae, flesh flies, snakes, gulls, corvids, opossums, bears, rats, armadillos, mustelids, skunks, canids, procyonids, cats, pigs, and humans. During their migration from their nests to the sea, hatchlings are preyed on by dipteran larvae, crabs, toads, lizards, snakes, seabirds such as frigatebirds, and other assorted birds and mammals. In the ocean, predators of the loggerhead juveniles include fish, such as parrotfish and moray eels, and portunid crabs. Adults are more rarely attacked due to their large size, but may be preyed on by large sharks, seals, and killer whales. Nesting females are attacked by flesh flies, feral dogs, and humans. Salt marsh mosquitos can also pester nesting females.
In Australia, the introduction of the red fox (Vulpes vulpes) by British settlers in the 19th century led to significant reductions in loggerhead sea turtle populations. In one coastal section in eastern Australia during the 1970s, predation of turtle eggs destroyed up to 95% of all clutches laid. Aggressive efforts to destroy foxes in the 1980s and 1990s has reduced this impact; however, it is estimated that it will be the year 2020 before populations will experience complete recovery from such dramatic losses.
Along the southeastern coast of the United States, the raccoon (Procyon lotor) is the most destructive predator of nesting sites. Mortality rates of nearly 100% of all clutches laid in a season have been recorded on some Florida beaches. This is attributed to an increase in raccoon populations, which have flourished in urban environments. Aggressive efforts to protect nesting sites by covering them with wire mesh has significantly reduced the impact of raccoon predation on loggerhead sea turtle eggs. On Bald Head Island in North Carolina, wire mesh screens are used on every confirmed nest to prevent excavation by resident red foxes. A new concern with the steel cage technique is interference with the normal development of the nestlings' magnetic sense due to the use of ferrous wire, which may disrupt the turtles' ability to navigate properly. Efforts are underway to find a nonmagnetic material that will prevent predators gnawing through the barrier.
Up to 40% of nesting females around the world have wounds believed to come from shark attacks.
Disease and parasites
Fibropapillomatosis disease caused by a form of the herpes-type virus threatens loggerheads with internal and external tumors. These tumors disrupt essential behaviors and, if on the eyes, cause permanent blindness. Trematodes of the family Spirorchiidae inhabit tissues throughout the body of the loggerhead, including vital organs, such as the heart and the brain. Trematode infection can be highly debilitating. For example, inflammatory trematode lesions can cause endocarditis and neurological disease. A nematode, Angiostoma carettae, also infects loggerheads, causing histologic lesions in the respiratory tract.
More than 100 species of animals from 13 phyla, as well as 37 kinds of algae, live on loggerheads' backs. These parasitic organisms, which increase drag, offer no known benefit to the turtle, although the dulling effect of organisms on shell color may improve camouflage.
Hatchlings range in color from light brown to almost black, lacking the adult's distinct yellows and reds. Upon hatching, they measure about 4.6 cm (1.8 in) and weigh about 20 g (0.7 oz). The eggs are typically laid on the beach in an area above the high-tide line. The eggs are laid near the water so the hatchlings can return to the sea. The loggerhead's sex is dictated by the temperature of the underground nest. Incubation temperatures generally range from 26-32°C (79-90°F). Sea turtle eggs kept at a constant incubating temperature of 32°C become females. Eggs incubating at 28°C become males. An incubation temperature of 30°C results in an equal ratio of male to female hatchlings. Hatchlings from eggs in the middle of the clutch tend to be the largest, grow the fastest, and be the most active during the first few days of sea life.
After incubating for around 80 days, hatchlings dig through the sand to the surface,usually occurs at night, when darkness increases the chance of escaping predation and damage from extreme sand surface temperatures is reduced. Hatchlings enter the ocean by navigating toward the brighter horizon created by the reflection of the moon and starlight off the water's surface.
Hatchlings can lose up to 20% of their body mass due to evaporation of water as they journey from nest to ocean. They initially use the undertow to push them five to 10 m away from the shore. Once in the ocean, they swim for about 20 hours, bringing them far offshore. An iron compound, magnetite, in their brains allows the turtles to perceive the Earth's magnetic field, for navigation. Many hatchlings use Sargassum in the open ocean as protection until they reach 45 cm (18 in). Hatchling loggerheads live in this pelagic environment until they reach juvenile age, and then they migrate to nearshore waters.
When ocean waters cool, loggerheads must migrate to warmer areas or hibernate to some degree. In the coldest months, they submerge for up to seven hours at a time, emerging for only seven minutes to breathe. Although outdone by freshwater turtles, these are among the longest recorded dives for any air-breathing marine vertebrate. During their seasonal migration, juvenile loggerheads have the ability to use both magnetic and visual cues. When both aids are available, they are used in conjunction; if one aid is not available, the other suffices. The turtles swim at about 1.6 km/h (0.9 kn; 0.4 m/s) during migration.
Like all marine turtles, the loggerhead prepares for reproduction in its foraging area. This takes place several years before the loggerhead migrates to a mating area. Female loggerheads first reproduce at ages 28–33 in Southeastern United States and Australia, and at ages 17–30 in South Africa. Age at first reproduction in the Mediterranean, Oman, Japan, and Brazil are unknown. Nesting loggerheads have a straight carapace length of 70–109 cm (28–43 in). Because of the large range, carapace length is not a reliable indicator of sexual maturity. Their estimated maximum lifespan is 47–67 years in the wild.
Female loggerheads first reproduce between the ages of 17 and 33, and their mating period may last more than six weeks. They court their mates, but these behaviors have not been thoroughly examined. Male forms of courtship behavior include nuzzling, biting, and head and flipper movements. Studies suggest females produce cloacal pheromones to indicate reproductive ability. Before mating, the male approaches a female and attempts to mount her, while she resists. Next, the male and female begin to circle each other. If the male has competitors, the female may let the males struggle with each other. The winner then mounts the female; the male's curved claws usually damage the shoulders of the female's shell during this process. Other courting males bite the male while he is attempting to copulate, damaging his flippers and tail, possibly exposing bones. Such damage can cause the male to dismount and may require weeks to heal. While nesting, females produce an average of 3.9 egg clutches, and then become quiescent, producing no eggs for two to three years. Unlike other sea turtles, courtship and mating usually do not take place near the nesting beach, but rather along migration routes between feeding and breeding grounds. Recent evidence indicates ovulation in loggerheads is mating-induced. Through the act of mating, the female ovulates eggs which are fertilized by the male. This is unique, as mating-induced ovulation is rare outside of mammals. In the Northern Hemisphere, loggerheads mate from late March to early June. The nesting season is short, between May and August in the Northern Hemisphere and between October and March in the Southern Hemisphere.
Loggerheads may display multiple paternity. Multiple paternity is possible due to sperm storage. The female can store sperm from multiple males in her oviducts until ovulation. A single clutch may have as many as five fathers, each contributing sperm to a portion of the clutch. Multiple paternity and female size are positively correlated. Two hypotheses explain this correlation. One posits that males favor large females because of their perceived higher fecundity (ability to reproduce). The other states, because larger females are able to swim more quickly to mating grounds, they have longer mating periods.
All sea turtles have similar basic nesting behaviors. Females return to lay eggs at intervals of 12–17 days during the nesting season, on or near the beach where they hatched. They exit the water, climb the beach, and scrape away the surface sand to form a body pit. With their hind limbs, they excavate an egg chamber in which the eggs are deposited. The females then cover the egg chamber and body pit with sand, and finally return to the sea. This process takes one to two hours, and occurs in open sand areas or on top of sand dunes, preferably near dune grasses that the females can use to camouflage the nest. The nesting area must be selected carefully because it affects characteristics such as fitness, emergence ratio, and vulnerability to nest predators. Loggerheads have an average clutch size of 112.4 eggs.
Carolus Linnaeus gave the loggerhead its first binomial name, Testudo caretta, in 1758. Thirty-five other names emerged over the following two centuries, with the combination Caretta caretta first introduced in 1902 by Leonhard Stejneger. The English common name "loggerhead" refers to the animal's large head. The loggerhead sea turtle belongs to the family Cheloniidae, which includes all sea turtles except the leatherback sea turtle. The subspecific classification of the loggerhead sea turtle is debated, but most authors consider it a single polymorphic species. Molecular genetics has confirmed hybridization of the loggerhead sea turtle with the Kemp's ridley sea turtle, hawksbill sea turtle, and green sea turtles. The extent of natural hybridization is not yet determined; however, second-generation hybrids have been reported, suggesting some hybrids are fertile.
Although evidence is lacking, modern sea turtles probably descended from a single common ancestor during the Cretaceous period. Like all other sea turtles except the leatherback, loggerheads are members of the ancient family Cheloniidae, and appeared about 40 million years ago. Of the six species of living Cheloniidae, loggerheads are more closely related to the Kemp's ridley sea turtle, olive ridley sea turtle, and the hawksbill turtle than they are to the flatback turtle and the green turtle.
Around three million years ago, during the Pliocene epoch, Central America emerged from the sea, effectively cutting off currents between the Atlantic and Indo-Pacific Oceans. The rerouting of ocean currents led to climatic changes as the Earth entered a glacial cycle. Cold water upwelling around the Cape of Good Hope and reduction in water temperature at Cape Horn formed coldwater barriers to migrating turtles. The result was a complete isolation of the Atlantic and Pacific populations of loggerheads. During the most recent ice age, the beaches of southeastern North America were too cold for sea turtle eggs. As the Earth began to warm, loggerheads moved farther north, colonizing the northern beaches. Because of this, turtles nesting between North Carolina and northern Florida represent a different genetic population from those in southern Florida.
The distinct populations of loggerheads have unique characteristics and genetic differences. For example, Mediterranean loggerheads are smaller, on average, than Atlantic Ocean loggerheads. North Atlantic and Mediterranean loggerhead sea turtles are descendants of colonizing loggerheads from Tongaland, South Africa. South African loggerhead genes are still present in these populations today.
Many human activities have negative effects on loggerhead sea turtle populations. The prolonged time required for loggerheads to reach sexual maturity and the high mortality rates of eggs and young turtles from natural phenomena compound the problems of population reduction as a consequence of human activities.
Loggerhead sea turtles were once intensively hunted for their meat and eggs; consumption has decreased, however, due to worldwide legislation. Despite this, turtle meat and eggs are still consumed in countries where regulations are not strictly enforced. In Mexico, turtle eggs are a common meal; locals claim the egg is an aphrodisiac. Eating turtle eggs or meat can cause serious illness due to harmful bacteria, such as Pseudomonas aeruginosa and Serratia marcescens, and high levels of toxic metals that build up through bioaccumulation.
The US West Coast is a critical migratory corridor for the Pacific loggerheads, in which these turtles swim across the Pacific to California’s coast from breeding grounds in Japan. Important foraging habitats for juveniles in the central North Pacific have been revealed through telemetry studies. Along with these foraging habitats, high levels of bycatch from industrial-scale fisheries have been found to overlap; with drift gillnets in the past and longline fisheries presently. Many juvenile loggerheads aggregate off the coast of Baja California Sur, Mexico, where small coastal fisheries increase these turtles' mortality risk; fishers have reported catching dozens of loggerheads with bottom-set gear per day per boat. The most common commercial fishery that accidentally takes loggerheads are bottom trawls used for shrimp vessels in the Gulf of California. In 2000, between 2,600 and 6,000 loggerheads were estimated to have been killed by pelagic longlining in the Pacific.
Fishing gear is the biggest threat to loggerheads in the open ocean. They often become entangled in longlines or gillnets. According to the 2009 status review of loggerheads by the Fisheries Service, drowning from entanglement in longline and gillnet fishing gear is the turtles’ primary threat in the North Pacific. They also become stuck in traps, pots, trawls, and dredges. Caught in this unattended equipment, loggerheads risk serious injury or drowning. Turtle excluder devices for nets and other traps reduce the number being accidentally caught.
Nearly 24,000 metric tons of plastic are dumped into the ocean each year. Turtles ingest a wide array of this floating debris, including bags, sheets, pellets, balloons and abandoned fishing line. Loggerheads may mistake the floating plastic for jellyfish, a common food item. The ingested plastic causes numerous health concerns, including intestinal blockage, reduced nutrient absorption and malnutrition, suffocation, ulcerations, or starvation. Ingested plastics release toxic compounds, including polychlorinated biphenyls, which may accumulate in internal tissues. Such toxins may lead to a thinning of eggshells, tissue damage, or deviation from natural behaviors.
Artificial lighting discourages nesting and interferes with the hatchlings' ability to navigate to the water's edge. Females prefer nesting on beaches free of artificial lighting. On developed beaches, nests are often clustered around tall buildings, perhaps because they block out the man-made light sources. Loggerhead hatchlings are drawn toward the brighter area over the water which is the consequence of the reflection of moon and star light. Confused by the brighter artificial light, they navigate inland, away from the protective waters, which exposes them to dehydration and predation as the sun rises. Artificial lighting causes tens of thousands of hatchling deaths per year.
Destruction and encroachment of habitat by humans is another threat to loggerhead sea turtles. Optimum nesting beaches are open-sand beaches above the high-tide line. However, beach development deprives them of suitable nesting areas, forcing them to nest closer to the surf. Urbanization often leads to the siltation of sandy beaches, decreasing their viability. Construction of docks and marinas can destroy near-shore habitats. Boat traffic and dredging degrades habitat and can also injure or kill turtles when boats collide with turtles at or near the surface.
Annual variations in climatic temperatures can affect sex ratios, since loggerheads have temperature-dependent sex determination. High sand temperatures may skew gender ratios in favor of females. Nesting sites exposed to unseasonably warm temperatures over a three-year period produced 87–99% females. This raises concern over the connection between rapid global temperature changes and the possibility of population extinction. A more localized effect on gender skewing comes from the construction of tall buildings, which reduce sun exposure, lowering the average sand temperature, which results in a shift in gender ratios to favor the emergence of male turtles.
Since the loggerhead occupies such a broad range, successful conservation requires efforts from multiple countries.
Loggerhead sea turtles are classified as endangered by the International Union for the Conservation of Nature and are listed under Appendix I of the Convention on International Trade in Endangered Species, making international trade illegal. In the United States, the Fish and Wildlife Service and National Marine Fisheries Service classify them as a threatened species under the Endangered Species Act. Loggerheads are listed as endangered under both Australia's Environment Protection and Biodiversity Conservation Act 1999 and Queensland's Nature Conservation Act 1992. The Convention on Migratory Species works for the conservation of loggerhead sea turtles on the Atlantic coast of Africa, as well as in the Indian Ocean and southeast Asia. Throughout Japan, the Sea Turtle Association of Japan aids in the conservation of loggerhead sea turtles. Greece's ARCHELON works for their conservation. The Marine Research Foundation works for loggerhead conservation in Oman. Annex 2 of the Specially Protected Areas and Wildlife Protocol of the Cartagena Convention, which deals with pollution that could harm marine ecosystems, also protects them. Conservation organizations worldwide have worked with the shrimp trawling industry to develop turtle exclusion devices (TEDs) to exclude even the largest turtles. TEDs are mandatory for all shrimp trawlers.
In many places during the nesting season, workers and volunteers search the coastline for nests, and researchers may also go out during the evening to look for nesting females for tagging studies and gather barnacles and tissues samples. Volunteers may, if necessary, relocate the nests for protection from threats, such as high spring tides and predators, and monitor the nests daily for disturbances. After the eggs hatch, volunteers uncover and tally hatched eggs, undeveloped eggs, and dead hatchlings. Any remaining live hatchlings are released or taken to research facilities. Typically, those that lack the vitality to hatch and climb to the surface die. Hatchlings use the journey from nest to ocean to build strength for the coming swim. Helping them to reach the ocean bypasses this strength-building exercise and lowers their chances of survival.
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collect biopsy samples for DNA studies, cage nests to prevent egg depredation, record location of nests and non-nesting emergences.
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Names and Taxonomy
Comments: See Dodd (1988) for a discussion of taxonomy. Dodd (1988, 1990) recommended that subspecies not be recognized. Accordingly, Crother (2012) and Turtle Taxonomy Working Group (2012) recognized no subspecies.
MtDNA data from major nesting populations in the Atlantic, Indian, and Pacific oceans and the Mediterranean Sea indicate that most breeding colonies have diagnostic genetic characteristics, indicating strong natal homing by nesting females (Bowen et al. 1994). Two major matrilines were identified, and each occurred in both Atlantic-Mediterranean and Indian-Pacific samples. This was attributed to recent interoceanic gene flow, probably mediated by the ability of this turtle to utilize habitats around southern Africa.
Crother et al. (2008) has returned to the use of "sea turtles" (rather than "seaturtles") as part of the standard English name for marine turtles. The combined name has not been used recently in the literature.