fisheries—contribute to sea-turtle declines and affect populations in U.S. waters. Data needed for accurate assessments of most populations are not available, and this prohibits diagnostic evaluation that can benefit management. In light of that problem, the National Marine Fisheries Service (NMFS) of the National Oceanic and Atmospheric Administration asked the National Research Council’s (NRC) Ocean Studies Board for advice on methods for improving sea-turtle population assessments. See Box S.1 for the committee’s full statement of task.

In response, the NRC appointed a committee of experts. The committee held two public meetings during which it received briefings from NMFS, the U.S. Fish and Wildlife Service (USFWS), and a number of other experts in sea-turtle biology and population assessments. In addition, the committee reviewed the available literature, met in closed sessions, and participated in several conference calls to complete work on its report. The report is intended to help NMFS and USFWS to improve population assessments of sea turtles; NMFS is responsible for the management of sea turtles in the water, and USFWS is responsible for sea turtles on land.

The committee was asked to evaluate current and emerging population assessment techniques that are being applied to provide advice to managers of sea turtles in the United States. Unlike the charge to the committee that prepared the 1990 NRC report (Decline of the Sea Turtles: Causes and Prevention), the charge to the present committee was not to review the wide array of threats and management actions related to sea turtles in the United States but rather to focus on the steps necessary to improve the assessments required for federal sea-turtle monitoring and management. This report describes a variety of assessment types and techniques, including beach samples, in-water surveys, genetic analyses, demographic2 analyses, bycatch (incidental take) information, and aerial surveys; reviews assessment methods; identifies information gaps; and suggests improvements for data collection. The fundamental theme underlying this report is that abundance assessment is essential but that abundance information alone is insufficient to understand the causes underlying trends in sea-turtle populations or to predict future trends. In addition to reliable abundance estimates, it is necessary to understand key demographics. To date, sufficiently complete demographic information has not been used in population assessments of sea turtles in the United States, in large part because it has not been available.

The committee believed that it was beyond its charge to discuss major stresses on sea-turtle populations, such as interactions with fisheries, and

2

Demographic or vital-rate parameters, such as birth and survival rates, indicate the potential for changes in a population.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement