A high percentage of turtle strandings have been attributed to a
disease that causes tumors to cover a turtle's body and impede
their vision, mouth, and movement.
Fibropapillomatosis (FP) is a debilitating disease that affects
sea turtles in Florida and many other parts of the world. Turtles
with FP have external tumors that may grow so large and hanging as
to hamper swimming, vision, feeding, and potential escape from
predators. These lesions have been reported in all sea turtle
species except in leatherbacks (Dermochelys coriacea). For
an unknown reason, the frequency of FP is much higher in green
turtles (Chelonia mydas) than in other species.
Based on information from the Florida Sea Turtle Stranding and
Salvage Network (STSSN) database, 22.2 percent of dead or
debilitated (i.e. stranded) green turtles (sample size=6027) found
in Florida between 1980-2005 had FP tumors. FP prevalence is low
among strandings of Kemp's ridleys (Lepidochelys kempii),
and loggerheads (Caretta caretta) in comparison to the
rate of FP in green turtles. FP prevalence in Kemp's ridleys and
loggerheads between 1980 and 2005 were 0.2 percent (sample
size=1,698) and 0.1 percent (sample size=15,237).
The history of FP in Florida dates back to at least 1938, when
FP was reported in green turtles that were captured in the Florida
Keys. This mysterious disease has now been observed in all major
oceans. Although the cause of FP is still not fully understood, a
leading suspect is a virus. There are only three facilities in
Florida where these papilloma-type tumors are surgically removed
from sea turtles. The survival rate of green turtles after surgery
is over 90 percent.
Between 1980 and 1998, all green turtle strandings with signs of
FP were found in southern Florida (south of 29°N latitude) where
over 20 percent of all green turtles exhibited FP. Since 1998, some
green turtles with FP have been found in northeast and northwest
Florida (north of 29°N latitude). Green turtles between 40- and
70-cm (curved shell length) had a higher incidence of FP tumors
than did smaller (less than 30 cm) or larger (more than 80 cm)
turtles. The incidence of FP in stranded green turtles during this
study period also varied by month; it was higher in winter than in
The appearance of FP tumors varies from smooth to
cauliflower-like with small spiky projections. The tumors arise
mostly on a turtle's soft skin tissue, around the neck, at the base
of flippers, and near the eye. They are occasionally found at the
seams between scales on the shell and plastron, which is the
ventral or lower area of the shell. The color of tumors can be
white, pink, red, gray, purple or black. The size of the tumor
varies from less than the size of a pea to larger than a
grapefruit. The number of tumors per turtle can be as many as 70. A
large mass of tumors can interfere with normal swimming and
feeding. Blood analyses have indicated that turtles with many
tumors are typically anemic. However, there were no differences in
blood parameters between non-diseased and mildly afflicted green
turtles with small amounts of tumors on their bodies.
Biologists are continuing to collect data and tissue samples in
studies of FP at hotspots for the disease such as the Indian River
Lagoon, Lake Worth Lagoon, Mosquito Lagoon, Florida Bay, and the
Florida Keys. In cooperative research facilitated by FWC,
veterinarians, immunologists, and pathologists are working to
understand what causes this mysterious disease.
Additional resources on fibropapillomatosis in green
FOLEY, A. M., B. A. SCHROEDER, A. E. REDLOW, K. J. FICK-CHILD,
AND W. G. TEAS. 2005.
Fibropapillomatosis in stranded green turtles (Chelonia mydas) from
the Eastern United States (1980-1998): trends and associations with
environmental factors. J. Wildl. Dis. 41(1): 29-41.
HERBST, L. H. 1994. Fibropapillomatosis of marine turtles. Annu.
Rev. Fish Dis. 4:389-425.
HIRAMA, S. and L. M. EHRHART.
Description, prevalence and severity of green turtle
fibropapillomatosis in three developmental habitats on the east
coast of Florida. Florida Scientist.