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Recovery Strategy for the Leatherback Turtle
- Executive summary
- Background: Current Canadian Status
- Biology and description
- Global distribution
- Global and Canadian size an trends
- Biological Factors
- Threats in the marine Environment
- Threats to the Nesting Environment
- Recovery goal and objectives
- Identification of knowledge gaps
- Actions completed or underway
- Statement of when one ore more recovery action plans will be completed
- Economic considerations and permitted activities
- Anticipated challenges for recovery
- Appendix-Glossary,Shedule of studies,Record of consultations
2.8.2 Threats to the Nesting Environment
The harvest of nesting adult females and their eggs for consumption or other uses continues to be a serious threat to leatherbacks throughout much of their range. The loss of nesting adults can lead to local extirpations, while the collection of eggs reduces the number of hatchlings available for future recruitment. To protect eggs from harvest, a number of conservation programs have developed hatcheries. While this may increase the total number of hatchlings released into the wild, artificial incubation - which is typically done at lower ambient beach temperatures - may result in the production of increased numbers of males (Morreale, et al.,1982; Mrsovsky, 1982; Dutton et al., 1985). The long-term recovery implications of this altered sex ratio have not been quantified.
While leatherback meat is considered unpalatable by most, poaching of free-swimming and nesting turtles for meat and/or oil does occur in some areas, including the British Virgin Islands, Dominican Republic, Jamaica, Puerto Rico and the U.S. Virgin Islands (Fleming 2001). A larger, more widespread problem is the collection of leatherback eggs for sale in local and/or foreign markets in the aforementioned countries as well as the Bahamas (Fleming 2001).
Coastal development and the resultant beach armouring (seawalls, revetments, riprap, sand bags, groins, and sand fences) put in place to protect upland structures from erosion can interfere with access to suitable nesting sites during construction, throughout the duration of the armouring and when structures deteriorate. Erosion associated with hard armouring structures also leads to the loss of nesting habitat (NMFS, 1992). Soft armouring such as beach nourishment can result in beaches unsuitable for nesting due to compaction or severe scarping and may also result in an altered physical nesting environment that can adversely impact hatchling development and hatching success.
Artificial lighting associated with coastal development, construction activities and roads can result in the disorientation of nesting adults and emerging hatchlings, resulting in failed nesting attempts and mortality of hatchlings. Adult females may avoid nesting on beaches with intense artificial lighting or ambient glow. When they do successfully nest on these beaches, hatchlings are attracted toward the artificial light source, which disrupts their natural sea finding behaviour, resulting in stress, dehydration, and predation (Witherington, 1992; Witherington & Bjorndal, 1991).
According to Davenport (1997), global warming is predicted to have deleterious effects on marine turtles, as it could potentially influence temperature-dependent sex determination. It can also be argued that increased hurricane activity associated with global climate change could result in increased nest loss due to amplified wind and wave erosion on leatherback nesting beaches. Lastly, alterations in ocean current patterns may accompany climate change, thereby affecting the migration and dispersal of marine turtles (Davenport, 1997).
Other Potential Threats
Other important threats to nesting habitats include: beach erosion, nest predation, beach driving, beach cleaning, beach mining, and exotic vegetation.
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