Population Viability Analysis: Loggerhead Turtles Brook Milligan - - PowerPoint PPT Presentation

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References Population Viability Analysis: Loggerhead Turtles Brook Milligan Department of Biology New Mexico State University Las Cruces, New Mexico 88003 brook@nmsu.edu Fall 2009 Brook Milligan Population Viability Analysis: Loggerhead

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Population Viability Analysis: Loggerhead Turtles

Brook Milligan

Department of Biology New Mexico State University Las Cruces, New Mexico 88003 brook@nmsu.edu

Fall 2009

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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PVA Example: Caretta caretta

Declining loggerhead turtle (Caretta caretta) populations Major mortality of eggs and hatchlings Extensive effort managing nesting beaches Is this the right management strategy? Are there other management actions that would be better?

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Nesting Females: Loggerhead Turtles

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Projected Growth Rates: Loggerhead Turtles (2009)

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Loggerhead Turtle Demographic Data

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Loggerhead Turtle Stage Projection Matrix

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Loggerhead Turtle Stable Stage Distribution

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Loggerhead Turtle Elasticity Analysis

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Loggerhead Turtle Elasticity Analysis

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Loggerhead Turtle Escaping via TED

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Loggerhead Turtle Escaping via TED

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Implementation of Turtle Exclusion Devices (TEDs)

1978: all marine turtles in southeastern U.S. listed as endangered 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 deployment

f TEDs

1986: threat to sue by environmental organizations over enforcement of Endangered Species Act 1989: mandatory use of TEDs for U.S. fishers 1989: Public Law 101-162, Section 609

Requires the U.S. to embargo shrimp harvested with commercial fishing technology that may adversely affect sea turtles Currently ≈40 countries have certified programs

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Shrimp Seizure: 2004 May 21

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

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Shrimp Seizure: 2006 January 13

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

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Shrimp Seizure: 2006 January 13

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

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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Historical Shrimp Prices

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Historical Shrimp Prices

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

Brook Milligan Population Viability Analysis: Loggerhead Turtles

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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 (Caretta

caretta) 2009 status review under the U.S. Endangered Species

Act. Technical report, Loggerhead Biological Review Team,

National Marine Fisheries Service. Crouse, D. T., L. B. Crowder, and H. Caswell. 1987. A stage-based population model for loggerhead sea turtles and implications 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 loggerhead sea turtle populations. Ecological Applications, 4:437–445.

Brook Milligan Population Viability Analysis: Loggerhead Turtles