Epidemic Levels of Tumors Found in Green Turtles

Last Year, Tumors Found on 90 Percent of Dead Maui Turtles

Off of Kaanapali Beach, a windsurfer hauled in a dead green sea turtle covered with large tumors. The next morning, May 2, the carcass of a decaying turtle without flippers floated into Lahaina Harbor near the breakwater.

Someone from the Aquatic Resources Division of the state Department of Land and Natural Resources came out that morning to get the two carcasses. For Skippy Hau, aquatic resources specialist, and Brooks Tamaya, the division's information specialist, the dead turtles were not unusual.

The turtle at Kaanapali weighed about 150 pounds, and was considered too heavy to air ship to Honolulu for necropsy, said Tamaya. The one at the harbor appeared to have been shark-bitten and was dead too long to yield much useful scientific information.

The two turtles were disposed of at the Central Maui Landfill.

Biologist George Balazs is Hawaii's leading expert on marine turtles. At the Honolulu laboratory of the National Marine Fisheries Service, Balazs spends almost all of his working hours studying the epidemic of fibropapilloma tumors in green turtles, which are on the list of threatened species.

"In the last 10 to 12 years, it has gone from a rarity to an every day fact of life," Balazs said of the tumors, now considered the greatest threat to the species' survival in Hawaii.

Maui is higher than the rest of the state in number of afflicted turtles, he said. Last year, 96 percent of the stranded or dead turtles recovered on Maui had tumors, while Oahu showed 64% with tumors.

Scientists in Florida have also seen an alarming increase in the number of green turtles with the same disease.

A herpes virus is the causative agent, but scientists don't yet know how the disease is spread among the sociable green turtles. The tumors are closer to "a wart gone wild" than to a malignant cancer, he said, but they are often deadly just the same.

The tumors frequently occur near the eyes and throat, and as they grow in size they impair the turtle's vision and ability to eat and breathe. The turtle begins "wasting away," Balazs said, and the disease affects internal organs as well.

Biologists are still concerned about other threats to turtles--litter, for instance, still poses a problem. Last year, an otherwise healthy turtle in Wailea drowned after it got tangled in a canvas bag. And despite laws protecting all of Hawaii's sea turtles, the green turtle is sometimes taken for food.

But the tumors are now the population's major threat. The increased incidence of tumors has led to intensive study of the problem, including a look at environmental factors that may contribute to the degradation of the turtles' habitat.

"We are truly getting more tumors on Maui," Balazs said. "It's a reflection of what's happening in the waters. It doesn't sound good, does it?"

Skippy Hau said he's noted an increased number of stranded turtles from West Maui in the last few years.

From 1993 to 1995, Balazs has had reports of 85 strandings from Maui, about one every two weeks. ("Strandings" include both dying the dead turtles). The first four months of 1996, 17 turtles have washed up on Maui--about one a week.

Scientists aren't the only ones who have seen an increase in the number of turtles with tumors.

Ron Hanson, a boat captain and scuba instructor, has been taking students to different dive spots around Maui for the last six years.

"When I first started diving on Maui, I didn't see any tumors," he said. "Then it began showing up in Lahaina. After a few years, I began seeing them in Kaanapali. Now they are all over the place."

Hanson has noticed a decrease in water visibility, also. "It used to be, on a good day, you could see 60 to 80 feet. Now it's more like 40 feet."

Near Mala Wharf, "over half of the turtles have tumors." Mala's waters have been "considerably dirtier than normal" from increased run-off, Hanson noted.

On Lanai, with exceptionally clear underwater visibility, all the turtles are healthy, he said.

Balazs said the tumors predominantly affect younger turtles, before they have reached sexual maturity. Also, after analyzing 11 years worth of data from 1,100 necropsied turtles, he's found that about 57% of those affected by tumors are females. Scientists don't know why the females are more vulnerable, he said.

Nearly all of Hawaii's green turtles start their lives in the French Frigate Shoals, 400 miles northwest of Kauai. Once they are a few years old, they make the long swim to the main islands.

Tumors have never been seen in the young turtles, before they leave the French Frigate Shoals. They occur most often once the turtle is 20 to 25 inches long, about 15 years of age, Balazs said.

The turtles don't reproduce until they reach 25 to 30 years of age, he said.

The population will be considered recovered when 5,000 nesting females are reported each year. Currently, there are 600 females counted each year in the French Frigate Shoals, he said.

Trying to connect the incidence of tumors with environmental factors hasn't yielded any direct links, he said. They appear mostly in areas near urban development, but there are also many tumored turtles off the largely undeveloped south shore of Molokai, the turtle researcher said.

In 1992, Balazs looked at pesticides and trace heavy metals in the tissues of green turtles. The contaminants were "barely discernible" in both the tumored turtles, and a control group of healthy turtles, he said.

Some researchers have tried removing the fibropapillomas, using cryosurgery to freeze the tumors. But the ones near the eyelids. which are most damaging to the turtles, tend to persist.

The National Marine Fisheries Service laboratory is entering new partnerships with other researchers, Balazs said, to expand investigation of the disease.

Marine biologist Hannah Bernard, education director of the Hawaii Wildlife Fund, said she's alarmed at the high rate of tumored turtles.

The new organization will be investigating ways of supporting the research on the turtles, she said. "We really need more information on why these turtles would have an epidemic life-threatening disease," she said.


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