Sea Turtle Injuries on Bald Head Island and their Effects on Fecundity
- 1. Sea Turtle Injuries on Bald Head Island and their Effects on Fecundity Joseph A Seebode Bald Head Island Conservancy College of the Holy Cross
- 2. Sea Turtles • Seven Species Worldwide – Found in tropics, subtropics, and temperate oceans of the world • DisFnguishing Features – Hard shell made of bone • Carapace + Plastron – Air Breathing – Lay eggs on land – Cold-‐blooded • Importance of protecFng sea turtles
- 3. Sea Turtles NesFng on BHI • Five species of sea turtles offshore – Only three species known to nest during summer months • Loggerheads typically lay between 100-‐120 eggs in a clutch – Two to three clutches in a nesFng season – Reach maturity around age 25 – Do not nest every year; nest every 2-‐4 years
- 4. IntroducFon-‐ Sea Turtle Injuries • Injuries decrease an animal’s fitness, or ability to survive • Sea turtles someFmes strand on beaches when they are sick or injured • Injuries may kill or seriously affect the health of a sea turtle – University of Florida Study • Hypothesis 1: There has been a change in the number of sea turtles that are injured each year • Hypothesis 2: Sea turtles with injuries will have less ability to acquire food and thus less energy to reproduce and produce eggs
- 5. Methods • Selected years 1993 to 2013 to look at BHI nesFng data; 1998 to 2013 for North Carolina stranding data from seaturtle.org • Recording injury descripFons from sea turtle data binders from the BHIC – Classifying sea turtles as having none, minor, or a major injury • Determining individual sea turtles by matching PIT and Flipper Tags • Comparing the number of eggs laid by sea turtles with no injuries, minor injuries, and major injuries as a measure of fecundity
- 6. Types of Injuries • Causes of sea turtle injuries: boat propeller strikes, entanglement in marine debris, and natural predaFon (such as sharks) • Major-‐ missing a flipper or parFal flipper, large breaks in the carapace, or damage to the skull • Minor – small piece missing from carapace or flipper, small gash
- 7. Results: Injured NesFng Sea Turtles on BHI 0 10 20 30 40 50 60 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Number of Nes+ng Sea Turtles Year Injured vs. Non-‐injured Nes+ng Sea Turtles on Bald Head Island Non-‐injured Injured
- 8. BHI NesFng Sea Turtles with Major Injuries 0 1 2 3 4 5 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Number of Sea Turtles w/ Major Injuries Year Number of Nes+ng Sea Turtles with Major Injuries on BHI
- 9. 0 10 20 30 40 50 60 70 80 90 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 Number of Strandings due Anthropogenic-‐Caused Injuries Year North Carolina Sea Turtle Strandings due to WatercraF Strikes
- 10. Effects on Fecundity • Average Number of Eggs Laid – No Injuries:117.18 • 946 nests – Minor Injuries: 123.23 • 162 nests – Major Injuries : 107.15 • 33 nests • Minor injuries significantly different from no injuries and major injuries; however major injuries not significantly different from no injuries
- 11. Discussion • Number of injuries per year does not change much, but sFll important to find ways to decrease injuries – 400,846 registered boats in NC in 2010 – Jet Propulsion boats found to be safer for sea turtles • # of eggs laid are within or close to the overall average for Loggerhead sea turtles: 100-‐120, even though some significantly differ from one another – Only 33 sea turtles with major injuries found injuries
- 12. Experimental Error • Some nesFng data could not be used: – Sea turtle not observed – Nest lost and egg data not available • Injuries on plastron not able to be observed • Difference in records year to year • RelocaFon egg count and excavaFon egg count may differ
- 13. Injury Recovery & Further Research • Importance of Sea Turtle Hospitals • Natural Healing • Further research required to more fully understand the relaFonship between an injury and fecundity • Study using more sea turtles with major injuries + comparing sea turtle fecundity before and aher an injury occurred • More safety precauFons should be put in place to prevent anthropogenic injuries + sea turtle rescue and rehabilitaFon centers should receive more funding
- 14. Thank you so much! Any QuesFons?