(Eretmochelys imbricata) Endangered species throughout its range, listed by the US Endangered Species Act (ESA) Listed on Appendix 1 of the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES)

The hawksbill turtle's status has not changed since it was listed as endangered in 1970. It is a solitary nester, is erratic in its nesting behavior, and thus, population trends or estimates are difficult to determine. The decline of nesting populations is accepted by most researchers. In 1983, the only known apparently stable populations were in Yemen, northeastern Australia, the Red Sea, and Oman. Commercial exploitation is the major cause of the continued decline of the hawksbill sea turtle. There is a continuing demand for the hawksbill's shell as well as other products including leather, oil, perfume, and cosmetics. Prior to being certified under the Pelly Amendment, Japan had been importing about 20 metric tons of hawksbill shell per year, representing approximately 19,000 turtles. A negotiated settlement was reached regarding this trade on June 19, 1992. The hawksbill shell commands high prices (currently $225/kilogram), a major factor preventing effective protection. Scientists believe the hawksbill may be on the verge of extinction.

Physical Characteristics

The hawksbill is a small to medium-sized sea turtle. In the U.S. Caribbean, nesting females average about 62-94cm in straight carapace length. Weight is typically to 80 kg in the wider Caribbean, with a record weight of 127 kg. Hatchlings average about 42 mm straight carapace length and range in weight from 13.5-19.5 g. The carapace is dark brown with yellow and reddish streaks, and the plastron is pale yellow.

Identifying Characteristics

Hawksbills have two pairs of prefrontal scales; thick, posteriorly overlapping scutes on the carapace; four pairs of coastal scutes; two claws on each flipper; and a beak-like mouth. The carapace is heart-shaped in very young turtles, and becomes more elongate or subovate with maturity. Its lateral and posterior margins are sharply serrated in all but very old individuals. The epidermal scutes that overlay the bones of the shell are the tortiseshell of commerce. They are unusually thick, and overlap posteriorly on the carapace in all but hatchlings and very old individuals. Carpacial scutes are often richly patterned with irregularly radiating streaks of brown or black on an amber background. The scutes of the plastron of Atlantic hawksbills are usually clear yellow, with little or no dark pigmentation. The soft skin on the ventral side is cream or yellow, and may be pinkish-orange in mature individuals. The scales of the head and forelimbs are dark brown or black with sharply defined yellow borders. There are typically four pairs of inframarginal scales. The head is elongate and tapers sharply to a point. The lower jaw is V-shaped.

Hawksbills utilize different habitats at different stages of their life cycle. Posthatchling hawksbills occupy the pelagic environment, taking shelter in weedlines that accumulate at convergence points. Hawksbills reenter coastal waters when they reach approximately 20-25 cm carapace length. Coral reefs are widely recognized as the resident foraging habitat of juveniles, subadults and adults. This habitat association is undoubtedly related to their diet of sponges, which need solid substrate for attachment. The ledges and caves of the reef provide shelter for resting both during the day and night. Hawksbills are also found around rocky outcrops and high energy shoals, which are also optimum sites for sponge growth. Hawksbills are also known to inhabit mangrove-fringed bays and estuaries, particularly along the eastern shore of continents where coral reefs are absent. In Texas, juvenile hawksbills are associated with stone jetties.

Hawksbills utilize both low- and high-energy nesting beaches in tropical oceans of the world. Both insular and mainland nesting sites are known. Hawksbills will nest on small pocket beaches, and, because of their small body size and great agility, can traverse fringing reefs that limit access by other species. They exhibit a wide tolerance for nesting substrate type. Nests are typically placed under vegetation.

It is estimated that hawksbills recruited into the reef environment at 35 cm in length would begin breeding 31 years later. However, the time required to reach 35 cm in length is unknown. As a result, actual age at sexual maturity is not known.

Range

The hawksbill occurs in tropical and subtropical seas of the Atlantic, Pacific and Indian Oceans. The species is widely distributed in the Caribbean Sea and western Atlantic Ocean, with representatives of at least some life history stages regularly occurring in southern Florida and the northern Gulf of Mexico (especially Texas); in the Greater and Lesser Antilles; and along the Central American mainland south to Brazil. Within the United States, hawksbills are most common in Puerto Rico and its associated islands, and in the U.S. Virgin Islands. In the continental U.S., the species is recorded from all the gulf states and from along the eastern seaboard as far north as Massachusetts, with the exception of Connecticut, but sightings north of Florida are rare.

Hawksbills are observed in Florida with some regularity on the reefs off Palm Beach County, where the warm Gulf Stream current passes close to shore, and in the Florida Keys. Texas is the only other state where hawksbills are sighted with any regularity. Most sightings involve posthatchlings and juveniles. These small turtles are believed to originate from nesting beaches in Mexico.

Nesting within the southeastern United States occurs principally in Puerto Rico and the U.S. Virgin Islands, the most important sites being Mona Island and Buck Island. Nesting also occurs on other beaches of St. Croix, and on Culebra Island, Vieques Island, mainland Puerto Rico, St. John and St. Thomas. Within the continental United States, nesting is restricted to the southeast coast of Florida and Florida Keys.

In the U.S. Pacific Ocean, there have been no hawksbill sightings off the west coast. Hawksbills have been observed in the Gulf of California as far as 29¡N, throughout the northwestern states of Mexico, and south along the Central and South American coasts to Columbia and Ecuador. In the Hawaiian Islands, nesting occurs in the main islands, primarily on several small sand beaches on the Islands of Hawaii and Molokai. Two of these sites are at a remote location in the Hawaii Volcanos National Park.

Feeding

The hawksbill sea turtle feeds on both animals and plants. Food items include algae, sea grasses, barnacles, fish and Portuguese men-of-war. Sponges and sea urchins are favorites of this species.

Human Impacts on Hawksbill Sea Turtle's Nesting Environment

1. The greatest threat on nesting beaches is poaching. Poaching of hawksbill eggs is a serious problem in Puerto Rico, and also occurs at lower levels in St. Thomas and St. Croix. Adult females are still butchered for their tortiseshell, but the practice is decreasing with better enforcement.
   
   
2. Erosion of nesting beaches can result in loss of nesting habitat. However, natural processes of beach erosion are not generally a significant threat.
   
   
3. Fortification of beachfronts to protect property from erosion can cause the loss of a dry nesting beach. It can also prevent females from getting to nesting sites and wash out nests. Beach nourishment buries nests and disturbs nesting turtles. Nourishment also results in heavy machinery, pipelines, increased human activity and artificial lighting on a project beach. This can create barriers for nesting sea turtles emerging from the ocean, preventing them from building nests, and it also disturbs nesting turtles on the beach.
   
   
4. Removal of sand for construction aggregate or renourishment of other beaches is a serious threat throughout the Caribbean. Sand removed from above the tide line is replaced very slowly from subtidal areas, a process which can take decades. Subtidal sand removal results in beach sand moving offshore.
   
   
5. Most nesting beaches are in private hands, and many of these have been developed. Development and landscaping of these nesting beaches can create impediments for nesting turtles. In addition, exotic plants such as sea oats can damage or destroy nests through root action.
   
   
6. Artificial lighting can cause disorientation or misorientation of both adults and hatchlings. Turtle hatchlings are attracted to light, ignoring or coming out of the ocean to go towards a light source, increasing their chances of death or injury. In addition, as nesting females avoid areas with intense lighting, highly developed areas may cause problems for turtles trying to nest.
   
   
7. Mechanical raking can result in heavy machinery repeatedly moving across a nest and compacting sand as well as causing tire ruts which may hinder or trap hatchlings. Rakes can penetrate the surface and disturb or uncover a nest. Disposing of debris on the high beach can cover nests and may alter nest temperature.
   
   
8. The most serious threat of nighttime use of a beach is the disturbance of nesting females. Heavy utilization of nesting beaches by humans may also result in lowered hatchling success due to sand compaction.
   
   
9. The use of off-road vehicles on beaches is a serious problem in many areas. It may result in decreased hatchling success due to sand compaction, or directly kill hatchlings. Tire ruts may also interfere with the ability of hatchlings to get to the ocean.
   
   
10. A variety of natural and introduced predators such as hogs, mongooses, ghost crabs and ants prey on hawksbill eggs and hatchlings.

Human Impacts in the Hawksbill Sea Turtle's Marine Environment

1. The extent to which hawksbills are killed or debilitated after becoming entangled in marine debris are unknown, but it is believed to be a serious and growing problem. Hawksbills have been reported entangled in monofilament gill nets, "fish nets", fishing line and rope.
   
   
2. Hawksbill turtles eat a wide variety of debris such as plastic bags, plastic and styrofoam pieces, tar balls, balloons and plastic pellets. Effects of consumption include interference in metabolism or gut function, even at low levels of ingestion, as well as absorption of toxic byproducts.
   
   
3. Incidental catch during fishing operations is an unquantified and potentially significant source of mortality. Gill nets, longlines and shrimp trawls all take turtles in Gulf of Mexico waters. In Puerto Rico, hawksbills are captured by a variety of fishing gear, including driftnets, gillnets, seines and spearguns. Gillnets and seines are widely deployed and are a particularly serious problem; these nets are sometimes set specifically for turtles.
   
   
4. In areas where recreational boating and ship traffic is intense, propeller and collision injuries are not uncommon.
   
   
5. In Puerto Rico, damage to coral reefs and other shallow water benthic systems from sedimentation and siltation has not been assessed as yet, but is known to be a serious problem in some areas, with some coral reefs completely destroyed by siltation.
   
   
6. Pesticides, heavy metals and PCB's have been detected in turtles and eggs, but their effect is unknown.
   
   
7. Raw sewage in Puerto Rico and the U.S. Virgin Islands has been released directly into nearshore waters. While a regional treatment plant has just been completed in Puerto Rico, monitoring has not been initiated.
   
   
8. The illegal take of hawksbills at sea has not yet been fully quantified, but it is a continuing problem.
   
   
9. Marine turtles are at risk when encountering an oil spill. Respiration, skin, blood chemistry and salt gland functions are affected.
   
   
10. The hawksbill's dependence on coral reefs for shelter and food link its well-being to the condition of reefs. Destruction of reefs from vessels anchoring, striking or grounding is a growing problem. Cruiseships and yachts are destroying portions of coral reefs with their anchors and anchor chains in the US Virgin Islands, Puerto Rico, the British Virgin Islands, Belize and elsewhere. There is also damage from recreational, diving and fishing boats anchoring indiscriminately on reefs.
    
    
11. International commerce in hawksbill shell (bekko) is the single most significant factor endangering hawksbill populations around the world. Japanese imports of raw bekko between 1970 and 1989 totalled 713,850 kg, representing more than 670,000 turtles; more than half the imports originated in the Caribbean and Latin America. While hawksbills are protected under CITES, trade continues for several reasons:
    
    
    • Not all countries have ratified CITES;
    • Some treaty signatories participate in trade by falsifying documents of origin;
    • Some treaty signatories ignore the treaty and trade openly in hawksbills and hawksbill products; and
    • Some treaty signatories have exercised their right to take exemption to treaty provisions as they affect sea turtles.
    
    
    
12. In nearshore waters, hawksbills are periodically captured in the colling water intakes of industrial facilities. In addition, illegal use of explosives for fishing is a concern, especially off the southeast coast of Puerto Rico.