Regression of Green Turtle Fibropapilloma Tumors at Honokowai

The Background

In his 1994 paper, Fibropapillomatosis of Marine Turtles, Dr. Larry Herbst wrote:

The duration and course of clinical GTFP (Green Turtle Fibropapillomas) are poorly understood, primarily because individual turtles with fibropapillomas of known duration have not been available for longitudinal studies. A few green turtles have been held in captivity long enough to provide some generalizations about the clinical course of the disease.

Jacobson et al. (Jacobson, E.R., Mansell, R.B., Sundberg, J.P., Hajar, L., Reichmann, M.E. Ehrhart, L.M., Walsh, M., Murru, F., Cutaneous fibropapillomas of green turtles (Chelonia mydas), J. Comp. Pathol. 101: 39-52) held six immature turtles with multiple cutaneous GTFP in captivity for several months. Some tumors on some animals decreased in size while others increased in some animals when examined 4 months after capture.

Ehrhart et al. maintained three green turtles with GTFP in captivity for approximately 3 months. During that time one animal lost several tumors, a second gained eight new tumors, and the third exhibited no changes. In these holding experiments, the length of time that the animals had the disease prior to capture is unknown. Field mark and recapture studies also indicate a variable clinical course. In these studies recapture rates are generally low and there is no control over the time interval between capture and recapture. For example, of 56 green turtles recaptured in the Indian River, 7% had tumors when first marked but had none at recapture, 14% contracted tumors between first capture and recapture, 38% had lesions both times, while 41% were free of lesions both times. These data, while limited in number, support the conclusions that the clinical course is prolonged and that some individuals may spontaneously recover from disease.

For the most part, tumors in the animals we observe grow worse from year to year. The condition of the turtle steadily decreases. The disease affects juvenile turtles far more profoundly than more mature animals. From the first signs of disease to complete emaciation can take as little as 24 months in youngsters.

We generally do not see adult to sub-adult tumor victims experiencing such an alarming rate of decline. Deterioration until the animal "disappears" is the norm, however.

Indian River studies indicate a regression rate of 7%. That is quite close to the percentage we have found at Honokowai. Of the 30 or so turtles resident to the area, visual evidence of tumors has disappeared completely in 3 turtles. Whether this apparent regression will remain permanent can be determined only by continued observation. Several other Honokowai turtles have shown either little worsening of the tumors, and in some cases there is actual shrinking. It is still too early to include these in regression reports, however.

Tutu [1990 Turtle 5]


Above is our best example of regression in a free-ranging wild Hawaiian green sea turtle. She carries tags numbered U 521 and U 522. We have known her since 1990. Her name is Tutu, Hawaiian for "grandmother". This is a video image of her in 1990 when we first sighted her. A golfball-sized tumor is clearly visible over her right eye. She had a smaller tumor in her left eye and one growing on her right flipper close by her tag.


In 1991 Tutu nested, presumably at the French Frigate Shoals. Here she is in 1992. Although this is another low quality video image, you can see that her eye tumor seems to be improving.

We do not have a decent photo of her in 1993 or 1994. In 1994, we did not sight her until late August, when she showed up sporting shiny new tags. It was clear she'd returned from another nesting season. Her tumors were not evident in 1994 and we have video to confirm this, but the image is poor so we will spare you.


Instead, we offer this excellent shot of her in 1995. As far as we can tell from visual inspection, she has now been free of tumors for two years. So for Tutu, there is hope.

Estrelita [1992 Turtle 6]


Here is our second example of regression. Estrelita seemed like a good name in 1992, when we first sighted this turtle. Estrelita was the sixth turtle we sighted that year.

We only have low quality video images of Estrelita from 1992, but as you can see, her right profile shows tumors beginning in her eye. Note the posterior tumor is larger, which is consistent with all double eye tumors in our Honokowai population. You can also see a small tumor beginning at the corner of the mouth.


We did not see Estrelita in 1993. In 1994, Estrelita was now a male! His growing tail meant we had a boy named Estrelita. This 1994 picture shows that his eyes were clearing, but tumors grew on his shoulders and armpits. It was cause for worry.


This is Estrelita in 1995. The tumors are gone. His eyes appear to be completely clear. Close examination of this animal revealed only slight scarring where the tumors once were. Estrelita is the only other animal that seems to have undergone complete regression based upon visual inspection.

In 1996, Estrelita was seen only twice, both times for only a few moments. We did not see evidence of a return of his tumors, but Estrelita has suffered what is most likely a collision with a boat prop. For more information, see the Summer 1996 update of Estrelita's biography.

Goofyfoot [1992 Turtle 7]


The Summer of 1996 has allowed us to add another turtle to our meager list of turtles whose condition has improved. When we first met Goofyfoot in 1992, she sported small incipient tumors in the posterior of both her eyes, as you can see in this 1992 video image. This made her typical of so many other Honokowai turtles, whose first tumors appear invariably in this location.

By 1993, her eye tumors hadn't grown and even looked improved, but a few new small tumors now appeared on her left shoulder and flipper. Although these were no bigger than a medium grape in size, their appearance worried us.

By 1994 all her tumors had shrunken. You had to inspect closely just to see them.

1995 brought even more improvement, with the body tumors completely gone and eye tumors barely noticeable. What was noticeable--and remarkably so--was a shift in Goofyfoot's behaviour from a friendly, confident, tolerant turtle to one who could be described as irritable and assertive.

We also noticed in that year that Goofyfoot's tail appeared longer than in previous years. We began to suspect we had an emerging male on our hands.

1996 proved this to be correct. Goofyfoot showed on July 2nd sporting the long trailing tail of a male sea turtle and no evidence of the tumors he had in previous years. Goofyfoot had clearly prospered. While he was still relatively small in length as far as males go, he certainly had increased in girth.


If you compare this image with the 1992 image above, you can see the remarkable difference in Goofyfoot's eye. We can now confidently add this young male to our list of regression cases and hope his good fortune will continue. He joins several animals whose condition improved while they made the transition to young male. Nui, Hilu, Estrelita and now Goofyfoot are all turtles whose tumors have improved during their puberty.

We don't know if this is significant. We are merely reporting it.


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Last modified 99/06/05
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