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Delaware Bay Sea Turtles: Habitats, Threats, and Conservation

Explore the diverse species of sea turtles found in Delaware Bay, their feeding habits, nesting locations, and the threats they face. Discover the significance of this habitat and the urgent need for conservation efforts.

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Delaware Bay Sea Turtles: Habitats, Threats, and Conservation

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  1. SEATURTLES Of Delaware Bay James R. Spotila Pamela Plotkin John Keinath

  2. The Magnificent Seven Green Turtle Herbivore-eats sea grasses and algae

  3. Hawksbill Spongivore

  4. Loggerhead A carnivore

  5. Olive Ridley A carnivore

  6. A carnivore Kemp’s Ridley

  7. Flatback A carnivore Only in Australia

  8. Leatherback Jelly-vore

  9. Loggerhead Kemp’s Ridley

  10. Delaware Bay and Sea Turtles • Juvenile sea turtles in Bay June- October • Rich source of crabs and other invertebrates • Genetic studies • loggerheads along northeastern states nest in Mexico, Florida, Georgia and South Carolina • Satellite Telemetry • Wassaw Island Georgia to mouth of Delaware Bay

  11. Methods • Aerial Surveys June- August 1997 • Cessna 172 • 100-224 mph • 300-500 ft above sea level • In-Water Captures June- September 1997 • Tangle nets • 100 yd x 8 ft x 10 in mesh • 100 yd x 30 ft x 6 in mesh • Large bullet surface floats • Retrieved every 30 minutes • 25 ft Parker boat • Sea Turtle Sighting Survey • Public users

  12. Aerial Surveys Four transect lines Two observers One data recorder (+ pilot) Strip transect 300 m wide June- August 1997 Locations of turtles Species Time Strip transect estimates of density (Epperly et al 1995)

  13. Sea Turtle Sighting Survey • Posters • Return post cards • Locations in New Jersey and Delaware

  14. Close up of Response Card

  15. Aerial Surveys • June – 10 loggerheads • July – 9 loggerheads • August- 14 loggerheads • Density- 21-33 turtles/100 km2

  16. Red dots- June Yellow dots- July Blue dots- August

  17. Red dots- June Yellow dots- July Blue dots- August

  18. Turtles were found near shipping channel Question- What happens in fall and winter?

  19. In Water Captures • 2 nets on 21 days • 103 hours • Observed 10 loggerheads (2 juveniles) • Captured 2 live male loggerheads • 90 and 108.2 cm • Found ½ of dead loggerhead floating in water

  20. Public Sea Turtle Sightings • 60 postcard responses • Most were recreational fishermen from lower Bay • A few sightings from Cape May- Lewes Ferry • 65 turtles • 57 loggerheads • 4 hawksbills- probably small loggerheads or Kemp’s Ridleys- spit out bait and hissed • 2 green turtles- probably loggerheads • 2 not identified to species • 12 of 65 turtles were caught by fishermen- 18.5%

  21. Sea Turtle Density LocationDensity (turtles/100 km2) • Delaware Bay- 21-33 • Lower Chesapeake Bay- 0-57 • Mid Chesapeake Bay- 0-8.5 • Pamlico Sound- 0-6.5 • Core Sound- 0-30 • Southern Georgia- 0-62

  22. Conclusions 1. Density of turtles is comparable or greater than in southeastern US 2. Lower Delaware Bay provides important habitat for loggerheads 3. Significant numbers of sea turtles are incidentally hooked by recreational fishermen 4. Many turtles swim in and around the shipping channel 5.Collision with boats and propellers may be a threat to turtles 6.Benthic trawling may be a significant threat to sea turtles in the Bay 7.Decline of horseshoe crabs threatens the food supply for these turtles.

  23. There is a serious need for more data about sea turtles in Delaware Bay if we are to reduce human impacts on these species

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