A Stage‐Based Population Model for Loggerhead Sea Turtles and Implications for Conservation

  title={A Stage‐Based Population Model for Loggerhead Sea Turtles and Implications for Conservation},
  author={Deborah T. Crouse and Larry B. Crowder and Hal Caswell},
Management of many species is currently based on an inadequate under- standing of their population dynamics. Lack of age-specific demographic information, particularly for long-lived iteroparous species, has impeded development of useful models. We use a Lefkovitch stage class matrix model, based on a preliminary life table developed by Frazer (1983a), to point to interim management measures and to identify those data most critical to refining our knowledge about the population dynamics of… 

Figures and Tables from this paper

Population modeling and implications for Caribbean hawksbill sea turtle management

Inferences from sea turtle population models point particularly to the need for maintaining unusually high annual survival rates for both benthic juveniles and adults for currently depleted Caribbean hawksbill populations.

Predicting the impact of Turtle Excluder Devices on loggerhead sea turtle populations

A stage—based population model for loggerhead sea turtles (Caretta caretta) is modified and updated and used to project potential population—level effects of the use of turtle excluder devices (TEDs) in trawl fisheries of the southeastern US.

How much sea turtle bycatch is too much? A stationary age distribution model for simulating population abundance and potential biological removal in the Mediterranean

Although the model assumes a stable population and provides only a rough estimate of abundance, these results suggest that the current bycatch level should be regarded as unsustainable for Mediterranean turtle populations.

Using an individual-based model for assessment of sea turtle population viability

Simulation results show that population persistence was most sensitive to fecundity and to survival at the pelagic juvenile stage, and a surprising finding is the relatively high importance of egg survival in terms of both hatching and hatchling success.

Estimates of vital rates for a declining loggerhead turtle (Caretta caretta) subpopulation: implications for management

Because subpopulations can differ geographically, genetically and/or phenotypically, using data from one subpopulation to derive vital rates for another, while often unavoidable, is not optimal. We

Life‐history constraints on maximum population growth for loggerhead turtles in the northwest Atlantic

Estimation of r max, while having some biases and uncertainty, encompassed values presently used in recovery planning for loggerhead turtles and offer additional information for the management of endangered and threatened species.

Estimates of vital rates for a declining loggerhead turtle (Caretta caretta) subpopulation: implications for management

These data provide managers with information specific to this subpopulation that can be used to develop recovery plans and conduct subpopulation-specific modeling exercises explicit to the challenges faced by turtles nesting in this region.

Establishing Reference Demography for Conservation: A Case Study of Macrochelys temminckii in Spring Creek, Georgia

It is suggested that the population parameters described at Spring Creek are the best approximation of reference demographic conditions for Macrochelys to date, and this study provides a general framework applicable for large, long-lived, endangered turtle species for which demographic data are unavailable.

Management inferences from a demographic analysis of sea lamprey (Petromyzon marinus) in the Laurentian Great Lakes

We use matrix models incorporating uncertainty in values of life history traits and density-dependent survival to assess pest management strategies implemented by the Great Lakes Fishery Commission



Population Growth Rates and Age Versus Stage-Distribution Models for Teasel (Dipsacus Sylvestris Huds.)

Mathematical models are developed to examine the population—level response of an herbaceous plant species (teasel), which was experimentally introduced into several habitats and monitored for 5 yr.


Comparison of observed size distribution and sex composition with projected stable populations indicated that the populations studied are near a stable structure and should show only modest changes in population size from year to year, in accord with one's expectations for a long-lived species growing in an ecologically stable habitat.

The Conservation of Sea Turtles: Practices and Problems

Until unequivocal data become available, turtle conservationists should continue to pursue common sense or logically sound restoration programs, but should constantly re-evaluate their actions in the light of the latest available knowledge and modify or desist from current approaches as necessary.

Nesting Activity of the Loggerhead Turtle (Caretta caretta) in South Carolina I: A Rookery in Transition

Nesting activity on Kiawah Island is undergoing development as a resort, but the builders have followed many of the management recommendations established relative to Caretta, and indicates that prudent beach development need not inhibit reproduction by Caretta.

Nesting frequency and success: implications for the demography of painted turtles

Nesting ecology and reproduction of painted turtles (Chrysemys picta) in southeast Michigan were intensively studied from 1975 to 1978 and data indicate that from 30 to 50% of the females possibly do not reproduce every year and that approx.

The ecology and migrations of sea turtles. 7, The West Caribbean green turtle colony. Bulletin of the AMNH ; v. 162, article 1

A unique contribution of the report is an extensive record of remigratory cycle-shifts, and tables showing composition of the nesting colonies of 1962-1972 with respect to past and future remigration-interval The ecology and migrations of sea turtles.

Some Aspects of the Nesting Behavior and Reproductive Biology of Sea Turtles

The relatively large number of yolkless eggs laid by many leatherbacks and by some hawksbills invites further study and some aspects of sea turtle nesting behavior and reproduction are compared to those of other chelonians.

Modulated Reproductive Periodicity in Chelonia

After 15 yr tagging at the nesting ground of Chelonia mydas at Tortuguero, Costa Rica, 447 remigration returns have been recorded. These confirm previous indications that some Tortuguero females

On the Growth of the Loggerhead Turtle, Caretta caretta, under Rearing Conditions

The present study was carried out to resolve the growing phases of the Loggerhead Turtle, Caretta caretta (Linne), which were raised from just hatch out stage to the 4.5 years old in the Aquarium,

Heavy Metals in Loggerhead Sea Turtle Eggs (Caretta caretta): Evidence to Support the Hypothesis that Demes Exist in the Western Atlantic Population

Data suggest the presence of groups of turtles and indirectly support the hypothesis that the Western Atlantic Loggerhead pcpulation is composed of demes, as well as suggesting no uniform geographic gradients exist in the nesting population.