FW364 Ecological Problem Solving Lab 7: Loggerhead turtle conservation

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Outline for Today Lab 7: Investigate loggerhead turtle conservation strategies A.Determine baseline population growth B.Comparison of turtle conservation strategies

Loggerhead Turtle Background A little big about loggerhead turtles… World’s largest hard-shelled turtle: average size ~35” and 300 lbs Long-lived (47-67 yrs) with delayed sexual maturity (17-33 yrs) Broadly distributed: Found in Atlantic, Pacific, and Indian oceans Endangered species Causes of decline: Mortality: Over-harvest (intentional harvest) By-catch by commercial fisheries Eating trash Reduced fecundity: Loss of nesting habitat Introduction of exotic nest predators e.g. Red fox in Australia  Subject of intense conservation efforts

Tracks for nine leatherback turtles Loggerhead Turtle Background Undergo large migrations Illustrate wide movement patterns of sea turtles Africa South America North America Europe

Turtle Conservation To reduce turtle by-catch in shrimp fisheries, fishermen are required to include turtle excluder devices (TEDs) in their nets TEDs are the primary management tool for reducing adult mortality

hawksbill turtle Turtle Conservation lost habitat existing habitat Dramatic sea turtle nesting habitat loss green turtle Conservation efforts: Protecting nesting beaches Protecting nests Transplanting eggs to hatcheries

Loggerhead Turtle Stages Five stages: (0) Hatchlings (1)Small juveniles (2)Large juveniles (3)Subadults (i.e., small adults) (4)Adults F4F Hatchlings Small Juveniles 01 S 12 S 23 S 34 S Subadults Adults 3F3F Large Juveniles 33 S 44 S 22 S 11 S Loggerhead Leslie matrix (from textbook):

Lab 7 – Loggerhead Turtle Conservation Goal: Use a stage model to evaluate two alternative conservation strategies: Increasing adult survival vs. adult fecundity Two parts: A.Determine baseline population growth B.Comparison of turtle conservation strategies

Part A: Determine baseline population growth for loggerhead turtles Lab 7 – Loggerhead Turtle Conservation Run a stage-structured simulation (see lab manual for parameters) and determine: Final population size (total number of turtles)

Part B: Comparison of turtle conservation strategies Lab 7 – Loggerhead Turtle Conservation Compare cost-effectiveness of two management strategies: 1.Use of TEDs to increase survival rates of subadult and adult turtles 2.Protection of nesting beaches and transplanting eggs to hatcheries to increase subadult and adult fecundities Givens: 1.Increasing the three subadult and adult survival rates ( 33 S, 34 S, 44 S) by 1% costs the fishermen $10,000 2.Increasing both subadult and adult fecundity rates ( 3 F, 4 F) by 1% costs taxpayers $2,500

Assumptions: Assumption about demographic stochasticity Assumption about density dependence Assumptions motivating your recommendations to policy makers (e.g., assumptions about human behavior, who should pay for conservation efforts, right to impose conservation costs on particular groups vs. sharing costs) Lab 7 – Loggerhead Turtle Conservation