In many coastal communities, especially in Central America and Asia, sea turtles have provided a source of food. During the nesting season, turtle hunters comb the beaches at night looking for nesting females. Often, they will wait until the female has deposited her eggs to kill her. Then, they take both the eggs and the meat. Additionally, people may use other parts of the turtle for products, including the oil, cartilage, skin and shell. Like other sea turtles, hawksbills are threatened by the loss of nesting and feeding habitats, excessive egg collection, fishery-related mortality, pollution, and coastal development. However, they are most threatened by wildlife trade. Hawksbills are particularly susceptible to entanglement in gillnets and accidental capture on fishing hooks. Sea turtles need to reach the surface to breathe, and therefore many drown once caught. Known as bycatch, this is a serious threat to hawksbill turtles. As fishing activity expands, this threat is more of a problem. : Pollution can have serious impacts on both sea turtles and the food they eat. For example, new research suggests that a disease now killing many sea turtles (fibropapillomas) may be linked to pollution in the oceans and in nearshore waters. When pollution contaminates and kills aquatic plant and animal life, it also destroys feeding habitats for sea turtles. Oil spills and urban runoff of chemicals and fertilizers all contribute to water pollution. An estimated 36% of all marine pollution from oil comes through drains and rivers from cities. Fertilizers are another huge marine pollutant. The runoff comes from farms and lawns, causing eutrophication from the extra nutrients. Eutrophication is an explosion of algal blooms that can deplete the water’s oxygen and suffocate marine life. Eutrophication has created enormous dead zones in many parts of the world, including the Gulf of Mexico. Improper sewage disposal is another factor that causes eutrophication. Because the ocean is so large, many assume that pollutants will be diluted and dispersed to safe levels, but in reality they create havoc on the oceans’ natural balance. Some toxins even become more concentrated as they break down and enter the food chain. Sea turtles are affected by pollution in more ways than one; they do not have to directly ingest a tar ball, for example, to be affected by it. Small marine animals, on the lower levels in the food chain, like plankton, absorb these chemicals as they feed. The chemicals then accumulate in these animals’ bodies, which makes the toxins much more concentrated than in the surrounding water. These small animals are then consumed by larger animals, like sea turtles, which continues to increase concentration levels of chemicals and pollutants. Sea turtles are vulnerable to ocean pollution at all stages of life, from eggs to hatchlings to juveniles to adults. Pollutants include things like toxic metals, pcb's, petroleum products, and agricultural and industrial runoff of contaminants such as fertilizers, chemicals, nutrients, and untreated waste. Pollutants may cause immediate harm to sea turtles through direct contact or can build up in tissues over time and lead to immunosuppression resulting in disease and death. Degradation of sea turtle habitat from pollution also poses a threat and can occur over large areas. Sea turtle habitat overlaps with areas most likely to be affected by offshore oil exploration and production. Petroleum pollution occurs from intentional discharge from vessels, vessel groundings, offshore oil exploration and production, transport of oil products, spills, and runoff of oil from land based sources. Sea turtles are also affected by ingesting food contaminated by oil or tar balls. Tar balls form when crude oil floating in the water degrades. A large percentage of dead hatchlings whose stomach contents have been examined have ingested tar balls. This disease is a threat to sea turtle populations worldwide. Also known as "FP", this disease causes cauliflower-shaped tumors on external soft parts and internal organs of a sea turtle. The exact cause of FP is still unknown, however, researchers believe there is a link to ocean pollution. External FP tumors can create drag and slow sea turtles down making them more vulnerable to predation and collisions with boats.Tumors around the eyes can obscure vision and eventually cause blindness, and tumors around the mouth can impair breathing and feeding. In some areas, many stranded and dead turtles have FP tumors. Research is still being done to determine the exact cause and transmission of this disease. FP was first seen in the 1930's in green turtles in the Florida Keys. In Hawaii, FP was not seen until the late 50's. It was first only observed in isolated areas but now occurs worldwide and in other species including loggerheads, Kemp's and olive ridleys, and flatbacks. Over 50% of green turtles found in Florida's Indian River are afflicted. Toxic metals may concentrate in the liver and kidneys of sea turtles. Toxins like mercury also pose a threat to human health. Chronic exposure to pollutants makes sea turtles susceptible to disease and death. Chronically ill turtles are also more vulnerable to predation and collisions with boats.
