Assessment of Sea-Turtle Status and Trends: Integrating Demography and Abundance (2010)Ocean Studies Board
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All six species of sea turtles found in U.S. waters are listed as endangered or threatened, but the exact population sizes of these species are unknown due to a lack of key information regarding birth and survival rates. The U.S. Endangered Species Act prohibits the hunting of sea turtles and reduces incidental losses from activities such as shrimp trawling and development on beaches used for nesting. However, current monitoring does not provide enough information on sea turtle populations to evaluate the effectiveness of these protective measures. This National Research Council report reviews current methods for assessing sea turtle populations and finds that although counts of sea turtles are essential, more detailed information on sea turtle biology, such as survival rates and breeding patterns, is needed to predict and understand changes in populations in order to develop successful management and conservation plans.
- Although counts of sea turtles are critical for assessing sea turtle populations, information on demographic rates, such as birth rates and mortality, is also essential to understanding and predicting trends in sea-turtle populations.
- In the United States, critical demographic rates have not been adequately determined for sea turtle populations.
- Inadequate information is available for population assessments either because the data have not been collected, have not been analyzed, or are not accessible to other researchers in a manner that allows them to be useful.
- Reviews of federal population assessments and research plans are not sufficiently rigorous and transparent.
- Sea-turtle population assessments in the United States are based too heavily on abundance estimates of adult females at nesting beaches. Without knowledge of accompanying changes in demographic rates for all life stages, the causes of population trends cannot be determined. Selection and evaluation of the options for sea-turtle population management depend on an understanding of the basis for the changes in sea turtle populations.
- The most important procedural enhancements would be improved coordination of data collection and availability, a more efficient and transparent permitting process, and increased archiving of tissue samples.
- Unnecessary obstacles to the collection and analysis of critical data exist, including inadequate training of sea turtle biologists in topics such as population statistics and modeling, and an inadequate process for issuing research permits.