How we define a problem often determines what we are willing to consider as a solution. When we define the impending extinction of a sea turtle species solely in terms of there being too few turtles, we are tempted to think of solutions solely in terms of increasing the numbers of turtles. Hence, some of our attempts to conserve sea turtles involve “halfway technology,” which does not address the causes of or provide amelioration for the actual threats turtles face. Programs such as headstarting, captive breeding, and hatcheries may serve only to release more turtle into a degraded environment in which their parents have already demonstrated that they cannot flourish. Furthermore, captive programs may keep turtles from serving important ecological functions in the natural environment, or place them at some disadvantage relative to their natural counterparts once released. Such programs can be contrasted with more appropriate technologies that directly address and correct particular problems encountered by sea turtles without removing them from their natural habitat. For example, installing turtle excluder devices in shrimp trawl nets will reduce mortality of adults and larger juvenile sea turtles, and using low pressure sodium lighting on beaches may prevent hatchlings and nesting females from becoming disoriented. In the final analysis, we need clean and productive marine and coastal environments. Without a commitment to such long term goals, efforts to protect sea turtles will be futile.

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. American Society of Ichthyologists and Herpetologists (ASIH)is collaborating with JSTOR to digitize, preserve and extend access to Copeia.Capture-recapture measurements of 11 wild green turtles, Chelonia mydas, and of 28 wild loggerhead turtles, Caretta caretta, in Florida indicate that growth in straight-line carapace length fits von Bertalanffy growth models better than logistic models. The von Bertalanffy model for green turtle growth yields estimates for age at maturity of between 18 and 27 years, based on the carapace length of the smallest nesting female (88 cm) and the mean length of all nesting females (99 cm). The model for loggerheads yields estimates of between 12 and 30 years, also based on carapace measurements of the smallest nesting female (74 cm) and the mean carapace length of all nesting females (92 cm). It is suggested that the upper estimates provide more realistic indications of mean age at first maturity.

Worldwide declines of marine turtle populations have forced a need for sound conservation policies to prevent their extinction. Loggerhead turtles, Caretta caretta, are declining rapidly at eastern Australian nesting beaches, which are visited by females from all feeding areas for the stock. In some feeding areas of eastern Australia, loggerheads have been protected from deleterious anthropogenic effects. Using long-term mark-recapture data from one such protected group of turtles feeding on Heron Island Reef, Queensland, we created a matrix model to analyse loggerhead demography. We also produced a model for the females nesting at Mon Repos, Queensland, a major rookery where the annual nesting population has declined at rates approaching 8% per year. As indicated by a similar model for loggerheads in the USA, our models predicted that small declines in annual survival rates of adult and subadult loggerheads can have a profound impact on population dynamics. A loss of only a few hundred subadult and adult females each year could lead to extinction of the eastern Australian loggerheads in less than a century. Survival in the first year of life is relatively less important in these long-lived and slow-maturing animals. At Mon Repos, nesting female survival is apparently so low that even beach protection efforts resulting in 90% hatchling emergence success would not prevent population decline. Our research suggests that continued mortality pressure on subadult and adult turtles in their dispersed feeding areas of eastern and northern Australia is a major threat to the eastern Australian loggerhead turtle population. Measures that protect adult and subadult loggerhead turtles should be supported, including the use of turtle excluder devices (TEDs) on prawn trawls.

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This paper presents a life table for the common mud turtle, Kinosternon subrubrum, in a fluctuating aquatic habitat on the Upper Coastal Plain of South Carolina, USA, using data gathered in a 20—yr mark—recapture study. Data on survivorship and fecundity (clutch size, per capita clutch frequency) were assessed and compared to previously published life table statistics for the slider turtle, Trachemys scripta, in the same body of water and for the yellow mud turtle, K. flavescens, in Nebraska. The annual survival rate for adult female Kinosternon (87.6%) is significantly higher than that of adult female Trachemys (77.4%). Similarly, male Kinosternon exhibit an annual survival rate (89.0%) significantly higher than that of male Trachemys (83.4%). The mean annual proportion of female Kinosternon that are reproductively active (50.7%) also is significantly higher than that of Trachemys (37.2%). In addition, survival rate from the time eggs are laid by Kinosternon until the hatchlings enter the aquatic environment (26.1%) is significantly higher than that for Trachemys (10.5%). Comparisons of our findings with those for K. flavescens indicate that these geographically separate populations of congeneric species also differ substantially in age at maturity, mean generation time, and the mean proportion of females that are reproductively active in any given year. Differences were also apparent in mean clutch frequencies and adult survival rates. The differences in life history traits between the two geographically separated populations of congeners seem to be as great as those between the two syntopic populations representing different families (Kinosternidae: K. subruburm and Emydidae: Trachemys scripta). The comparison of life tables for two species from different families having different ecological and evolutionary histories, but living in the same habitat, and of congeneric species in different habitats, is instructive regarding the biological flexibility of species under natural conditions. However, the study suggests that environmental variability has a greater effect on life table statistics than do phylogenetic relationships.