Sea Turtle Injuries on Bald Head Island and their Effects on Fecundity Joseph A Seebode Bald Head Island Conservancy College of the Holy Cross
Sea Turtle Injuries on Bald Head Island and their Effects on Fecundity
Joseph A Seebode Bald Head Island Conservancy
College of the Holy Cross
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
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
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
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
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
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
Num
ber o
f Nes+n
g Sea Tu
rtles
Year
Injured vs. Non-‐injured Nes+ng Sea Turtles on Bald Head Island
Non-‐injured
Injured
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
Num
ber o
f Sea Turtle
s w/ Major In
jurie
s
Year
Number of Nes+ng Sea Turtles with Major Injuries on BHI
0
10
20
30
40
50
60
70
80
90
1996 1998 2000 2002 2004 2006 2008 2010 2012 2014
Num
ber o
f Stran
dings d
ue Anthrop
ogen
ic-‐Cau
sed In
jurie
s
Year
North Carolina Sea Turtle Strandings due to WatercraF Strikes
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
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
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
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
Thank you so much!
Any QuesFons?