Saving the Loggerheads By Brian Vajanaphanich and Sean Wang

Loggerhead Background Most abundant marine turtle in the U.S. Live from years Grow up to 3 feet Females lay ~80 eggs/year Females start laying eggs at 22

Loggerhead Problems Nesting habitat destruction Human lighting directing hatchlings away from ocean Turtles caught in fish nets Population declining

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Loggerhead Options Maintaining nesting habitat Implementation of Turtle Excluder Device on fish nets

Loggerhead Egg Saving Egg mortality rates can sometimes reach 95% Human affects on turtles cause babies/eggs to – Crawl the wrong way when trying to enter the water for the first time – Be crushed under human activity on beaches The average mortality rate for turtle babies and eggs is ~32.53%

Loggerhead TED Tens of thousands of turtles per year are killed by bottom trawling fishing nets The main victims of fishing nets are turtles aged between 9-16 years old TEDs(Turtle Exclusion Devices) allow turtles to pass through fishing nets without being trapped and killed

Loggerhead Simulation Leslie matrix used to model population Estimated 55 year survival Age (Years) Survival Rate (%/year) Fecundity (Eggs/year)

Loggerhead Population Under current conditions the population is expected to drop by ~3% annually

Eigenvalues/Eigenvectors When a square matrix is multiplied by a vector, the resulting vector is a scalar multiple of the original vector There are as many possible eigenvalues as the number of rows and columns in the matrix Eigenvalues>1 show growth, <1 show death

Loggerhead R Coding Created a 55 by 55 matrix that updated the population vector. Graphed the population over time Calculated and graphed the eigenvalue at different survival rates

Loggerhead Option 1 We can increase the survival rate of 0-1 year olds (eggs/babies)

Loggerhead Option 2 We can increase the survival rate of 9-16 year olds by implementing TEDs

Loggerhead Solution If TEDs can raise the survival rates of 9-16 year olds by at least ~6.6% then the Loggerhead Turtles will be saved.

Loggerhead TED Talk TEDs are estimated to reduce mortality rates from trawling nets by 97% Only reduces shrimp catch by 5-13% Relatively cheap to implement.

High Fives Only!!!!!

Acknowledgements Crouse, Deborah T., Larry B. Crowder, and Hal Caswell. "A Stage-Based Population Model for Loggerhead Sea Turtles and Implications for Conservation." Ecology 68.5 (1987): Jstor. Ecological Society of America, 07 Apr Web. 30 July Shiffman, David. "Turtle Excluder Devices: Analysis of Resistance to a Successful Conservation Policy." Southern Fried Science. Southern Fried Science, 07 Jan Web. 30 July William Cuello, Robert Guy, Timothy Lewis, Sebastian Schreiber, King David, and William Cuello

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