Threats to sea turtles are numerous and have caused many sea turtle species to be endangered. Of the seven extant species of sea turtles, six in the family Cheloniidae and one in the family Dermochelyidae, all are listed on the IUCN Red List of Endangered Species. The list classifies six species of sea turtle as "threatened", two of them as "critically endangered", one as "endangered" and three as "vulnerable". The flatback sea turtle is classified as "data deficient" which means that there is insufficient information available for a proper assessment of conservation status. Although sea turtles usually lay around one hundred eggs at a time, on average only one of the eggs from the nest will survive to adulthood. While many of the things that endanger these hatchlings are natural, such as predators including sharks, raccoons, foxes, and seagulls, many new threats to the sea turtle species are anthropogenic.
Artificial lighting
Artificial lighting is a threat to adult and hatchling sea turtles. Sea turtles use the brightest horizon as a guide to the ocean. This was created by celestial lights reflecting off the ocean’s surface. With human development along the coast, artificial light sources are growing in abundance. Unfortunately, these human-made lights are brighter than celestial lights, causing sea turtles to move toward them. A sea turtle not going in the direction of the ocean is referred to as a disorientation event. Disorientations lead to an increased risk of predation, exhaustion, dehydration, and/or injury. These events are often fatal. Disorientations can be caused by any light source that is directly or indirectly seen from the beach. Also, heavily lit beaches may cause an adult to have a false crawl. This is when the female decides the beach is not suitable for her nest and goes back to the water. False crawls cause exhaustion for the adult and may lead to her releasing her eggs in the ocean. This would be fatal to all the eggs.
As awareness of the negative impact artificial lighting has on sea turtles has grown, there have been several large-scale conservation efforts by Marine Life programs and conservation groups to educate the public on turtle conservation. Communities situated on or near a beach have been warned of the effects excessive lighting has on sea turtles and there have been substantial attempts to darken beaches and replace harmful artificial lighting with turtle-safe lights. Coastal communities have also been creating and updating their lighting ordinances with the common goal to help save sea turtles. Lighting ordinances allow local governments to enforce safer lighting for sea turtles.
Magnetic interference
Ferrous metal wire mesh screens are commonly used to protect sea turtle nests from predators' excavating and devouring the eggs and hatchlings. A new concern is that nestlings' delicate magnetic sense may not develop normally in the presence of the magnetic field interference from these steel mesh cages. The effects of the use of steel mesh as a cage material may not be known for many years until assessments can be made of the success rate of the first adult populations that developed within such cages begin attempting landfall for nest-making. Gravid turtles or their hatchlings may also be affected by the presence of magnetic fields arising from power cables, iron debris, steel seawalls or other human activities that locally modify earth's magnetic field.
Oil spills and marine pollution
Marine pollution is both directly harmful to sea turtles as well as indirectly, through the deterioration of their natural habitats. Some of the most dangerous ocean pollutants include toxic metals, PCBs, fertilizers, untreated waste, chemicals, and a variety of petroleum products. Oil spills are particularly dangerous to sea turtles. Although oil does not tend to stick to them as it does to other marine life, sea turtles are still at risk when they surface for air, where oil can get in their eyes, skin, and lungs, which can lead to significant health problems. Even if they are not directly in contact with marine pollution, sea turtles can still ingest harmful chemicals through the food they eat. Oil is also a cause for the death of seagrass, which is a staple in the diet of the green turtle. The diets of the hawksbill sea turtle, loggerhead sea turtle, and Kemp's ridley sea turtle species have also been affected by the oil's role in the reduction of certain sponges and invertebrates. Extended exposure has been found to deteriorate the health of a sea turtle in general, making it more weak and vulnerable to a variety of other threats.