We examined data collected by the US Sea Turtle Stranding and Salvage Network on 4,328 green turtles (Chelonia mydas) found dead or debilitated (i.e., stranded) in the eastern half of the USA from Massachusetts to Texas during the period extending from 1980 to 1998. Fibropapillomatosis (FP) was reported only on green turtles in the southern half of Florida (south of 29 degrees N latitude). Within this region, 22.6% (682/3,016) of the turtles had tumors. Fibropapillomatosis was more prevalent in turtles found along the western (Gulf) coast of Florida (51.9%) than in turtles found along the eastern (Atlantic) coast of Florida (11.9%) and was more prevalent in turtles found in inshore areas (38.9%) than in turtles found in offshore areas (14.6%). A high prevalence of FP corresponded to coastal waters characterized by habitat degradation and pollution, a large extent of shallow-water area, and low wave energy, supporting speculation that one or more of these factors could serve as an environmental cofactor in the expression of FP. A high prevalence of FP did not correspond to high-density green turtle assemblages. Turtles with tumors were found most commonly during the fall and winter months, and the occurrence of tumors was most common in turtles of intermediate size (40-70-cm curved carapace length). Stranded green turtles with tumors were more likely to be emaciated or entangled in fishing line and less likely to have propeller wounds than were stranded green turtles without tumors. Turtles with and without tumors were equally likely to show evidence of a shark attack. The percent occurrence of tumors in stranded green turtles increased from approximately 10% in the early 1980s to over 30% in the late 1990s. Fibropapillomatosis was first documented in southernmost Florida in the late 1930s and spread throughout the southern half of Florida and the Caribbean during the mid-1980s. Because green turtles living in south Florida are known to move throughout much of the Caribbean, but are not known to move to other parts of the USA or to Bermuda, the spread and current distribution of FP in the western Atlantic, Gulf of Mexico, and Caribbean can be explained by assuming FP is caused by an infectious agent that first appeared in southern Florida. Aberrant movements of captive-reared turtles or of turtles that are released into areas where they were not originally found could spread FP beyond its current distribution.
Detailed post-breeding movement data is presented for hawksbill turtles tracked by satellite telemetry from Mona Island, Puerto Rico. Seven nesting females and 8 breeding males were tracked. Females traveled for 3 to 53 d to reach their foraging grounds, swimming distances of 84 to 2051 km (mean 867 km, n = 7) at average speeds of 23.5 to 38.7 km d -1 (n = 7). Males traveled for <1 to 22 d, covering distances of < 2 to 476 km (mean 101 km, n = 8) at average speeds of 13.0 to 24.7 km d -1 (n = 5). One of the tracked males remained at the Mona Island breeding grounds for 11 mo before being recaptured there. The migration of 2 other male hawksbill turtles returning to Mona Island the following year from their foraging grounds was also documented. Descriptions of the foraging habitats used by these adult turtles are provided. The significant differences observed in migratory range between males and females are interpreted in an evolutionary context of food abundance predictability; an alternative hypothesis of geographic variation in mortality rates is also considered.
KEY WORDS: Hawksbill turtle · Eretmochelys imbricata · Migration · Mona Island · Puerto RicoResale or republication not permitted without written consent of the publisher
The effectiveness of recovery plans for threatened and endangered species has been questioned in academic and political domains. A comprehensive assessment of species recovery plans concluded that quantification and prioritization of threats have received insufficient attention, which contributes to the failure of some plans. On the basis of this assessment, we developed and implemented a detailed analysis of threats in the Recovery Plan for the Northwest Atlantic Population of the Loggerhead Sea Turtle (Caretta caretta), produced by the National Marine Fisheries Service and US Fish and Wildlife Service. The analytical approach that we designed and summarize here provides an objective process for quantifying known threats and prioritizing recovery actions in terms of their relative impact on population growth rate (λ) of the loggerhead sea turtle. Although this process was developed for loggerhead sea turtles, it can be applied to other species.
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