population viability analysis: loggerhead...

References

Population Viability Analysis: Loggerhead Turtles

Brook Milligan

Department of BiologyNew Mexico State University

Las Cruces, New Mexico [email protected]

Fall 2009

Brook Milligan Population Viability Analysis: Loggerhead Turtles

mailto:[email protected]

References

PVA Example: Caretta caretta

Declining loggerhead turtle(Caretta caretta)populations

Major mortality of eggs andhatchlings

Extensive effort managingnesting beaches

Is this the rightmanagement strategy?

Are there other managementactions that would bebetter?


References

Nesting Females: Loggerhead Turtles


References

Projected Growth Rates: Loggerhead Turtles (2009)


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Loggerhead Turtle Demographic Data


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Loggerhead Turtle Stage Projection Matrix


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Loggerhead Turtle Stable Stage Distribution


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Loggerhead Turtle Elasticity Analysis


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Loggerhead Turtle Escaping via TED


References

Implementation of Turtle Exclusion Devices (TEDs)

1978: all marine turtles in southeastern U.S. listed asendangered

1978–1980: initial development to TEDs

1981: voluntary program for shrimp fishers

1980–1984: improvements in TED technology

1985–1986: increased efforts to engage voluntary deploymentof TEDs

1986: threat to sue by environmental organizations overenforcement of Endangered Species Act

1989: mandatory use of TEDs for U.S. fishers

1989: Public Law 101-162, Section 609Requires the U.S. to embargo shrimp harvested withcommercial fishing technology that may adversely affect seaturtlesCurrently ≈40 countries have certified programs


References

Shrimp Seizure: 2004 May 21

10,000 pounds of shrimp seized for lack of federally requiredmarine conservation equipment.


References

Shrimp Seizure: 2006 January 13

6,330 pounds of shrimp seized because two of four Turtle ExclusionDevices and one By-catch Reduction Device were sewn shut.


References

Historical Shrimp Prices

Value of seized catches: $3.00–$5.00 per pound landed =⇒$20,000–$50,000


References

Conant, T. A., P. H. Dutton, T. Eguchi, S. P. Epperly, C. C. Fahy,M. H. Godfrey, S. L. MacPherson, E. E. Possardt, B. A.Schroeder, J. A. Seminoff, M. L. Snover, C. M. Upite, and B. E.Witherington. August 2009. Loggerhead sea turtle (Carettacaretta) 2009 status review under the U.S. Endangered SpeciesAct. Technical report, Loggerhead Biological Review Team,National Marine Fisheries Service.

Crouse, D. T., L. B. Crowder, and H. Caswell. 1987. Astage-based population model for loggerhead sea turtles andimplications for conservation. Ecology, 68:1412–1423.

Crowder, L., D. T. Crouse, S. S. Heppell, and T. H. Martin. 1994.Predicting the impact of turtle excluder devices on loggerheadsea turtle populations. Ecological Applications, 4:437–445.


population viability analysis: loggerhead...

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