UNIT 25 

 SEA TURTLES 



gillnct tkslieries for coastal species, including sharks, 

 and the JongHne and gilinet fisheries tor sword- 

 fish, tuna, and sharks. 



Propeller strikes and vessel collisions also pose 

 significant threats to sea turtles, especially in areas 

 of high human population, where recreational boat 

 traffic is heaw and coastal ports are active. 



Habitat Concerns 



Coastal development can deter or interfere with 

 nesting, affect nest success, and degrade foraging 

 habitats for sea turtles. Nesting beaches of the 

 southeastern United States and Hawaii are essen- 

 tial to the recovery and survival of sea turtles. Many 

 nesting beaches have already been significantly 

 de£;raded or destroved. Nesting habitat is threat- 

 ened bv rigid shoreline protection or "coastal 

 armoring" such as sea walls, rock revetments, and 

 sandbag installations. Many miles of once produc- 

 tive nesting beach have been permanently lost to 

 this type of shoreline protection. Additional!)', 

 nesting habitat can be negatively impacted by 

 beach nourishment projects that result in altered 

 beach and sand characteristics that affect nesting 

 activity and nest success. Artificial beachfront light- 

 ing, increased human activity, and beach driving 

 also seriously threaten species recovery. In light of 

 these issues, conservation and long-term protec- 

 tion of sea turtle nesting habitats is an urgenr and 

 hisjh priority need. 



Marine Debris 



Ingestion of marine debris can be a serious 

 threat to sea turtles. When feeding, sea Turtles can 

 mistake debris tor natural food items. An exami- 

 nation of the feeding habits of loggerhead 

 hatchlings inhabiting offshore convergence zones 

 revealed a high incidence of tar and plastic inges- 

 tion. Some types of marine debris may be directly 

 or indirectly toxic, such as oil. Other types of 

 marine debris, such as discarded or derelict fish- 

 ino £;car, may entangle and drown sea turtles. 



Disease 



A disease known as fibropapillomatosis (FP), 

 oritrinallv identified in green turtles, but now af- 



Number 

 of nesters 



550 - 



500 



450 



350 



300 

 250 

 200 

 150 

 100 

 50 



L 



I 



I 



J I I L_ 



_L_ 



I 



_L_ 



73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 



Year 



fecting loggerheads and olive ridleys as well, has 

 emerged as a serious threat to their recovery. The 

 disease is most notably present in green turtles of 

 Hawaii, Florida, and the Caribbean. FP is expressed 

 as tumors which occur primarily on the skin and 

 eves, and the disease can be fatal. In Hawaii, green 

 turtles afflicted with FP have a high incidence of 

 tumors in the oral cavity, whereas oral tumors have 

 not been found in Florida or other areas. The cause 

 of the disease remains unknown. The disea.se has 

 been systematically monitored in several locales in 

 Hawaii. At a study site on southern Molokai, for 

 example, where tumors were virtually unknown 

 before 1988, the prevalence of rumored sea turtles 

 ranged from 42 to 56% during the 1995-97 sur- 

 veys. In Florida, up to 50% of the immature green 

 turtles captured in the Indian River Lagoon are in- 

 fected, and there are similar reports from other sites 

 in Florida, including Florida Bay, as well as from 

 Puerto Rico and the U.S. Virgin Islands. In Florida, 

 rhe disease has been found to affect up to 1 3% of 

 loggerheads inhabiting Florida Bay. FP appears ro 

 be the chief threat ro full recovery of the Hawaii 

 green turtle population, and the disease could hinder 

 the recovery of green turtle populations elsewhere 

 as well. Research to determine the cause of this dis- 

 ease is a high priority. 



90 91 92 93 94 95 96 97 



Figure 25-2 



Population estimates for 

 nesting green turtles on East 

 Island. 



265 



