Principal Investigator: Todd Jones (PIFSC)
Co-Principal Investigator: Summer Martin (PIFSC)

Project title

Improving population vital rate data for the Hawaiian green sea turtle


The Hawaiian green sea turtle population (Central North Pacific distinct population segment) has shown an increasing trend in nesting abundance (> 5% annually) over the past three decades, however, this does not necessarily reflect an increase in the total population if recruitment is not also increasing. Population estimates have been derived from over 30 years of nesting data, however, limited data on nesting vital rates provides little understanding of how the population is responding to increased nesting. Stranding data from a stranding and salvage program for the main Hawaiian Islands suggest a stable or decreasing trend in the number of stranded turtles, which is inconsistent with what would be expected if the population is actually increasing. Data on nesting vital rates in the Northwestern Hawaiian Islands will help with determining whether or not increased nesting has also led to increased recruitment by measuring the actual productivity and success of nesters.  

Green sea turtle

Research Objectives

1) Collect data on nesting vital rates / productivity to quantify the contribution of increased nesting to the population and

2) Use the data from nesting female abundance and nesting demographic data in a stage-based population model to estimate total abundance.

Project significance, impacts, and applications

The significance of the study is building on nesting abundance information for this DPS that recently was maintained as threatened under the guidelines of the Endangered Species Act through the recent 5-year review (Seminoff et al. 2015). The nesting abundance trends were heavily used in the 5-year determination; yet, there hasn’t been collection of vital rates and hatching productivity in nearly 2 decades. These data are critical to improve our understanding of population dynamics of this recovering DPS.

These data directly fulfill two aspects of the SAIP Research Themes:

Life History and Vital Rates. Population models and evaluation of trends, threats, and extinction risk require the best possible regional estimates of vital rates (averages, inter-individual variability, and temporal and spatial variation) and are enhanced by understanding environmental mechanisms that may affect these rates. Priority should be given to the most serious data and analysis gaps with respect to estimation of species- and stage-specific vital rates, and vital rate data should be collected over space and time to improve trend information. Activities geared toward addressing life history and vital rate data gaps should focus on:

  • Estimation of breeding rates, clutch frequency, and hatchling-cohort production,
  • Continued advancements to collect demographic data and prioritize the need to estimate each vital rate.

Abundance. In-water life stages fall explicitly under NMFS jurisdiction; however, because data from nesting beaches can provide important information about in-water phenomena, nesting beach data collection and analysis may be appropriate for some programs. Sea turtle survey, monitoring, and abundance analysis activities include:

  • Improving abundance estimation
  • Evaluating the study design of and complementing or expanding past and present long-term studies

Link to current research blog: