Hokule'a crew impressed, amazed
By Jan TenBruggencate
Advertiser Science Writer
The Hawaiian green sea turtle recovery just keeps coming, thanks to the big mama turtles on the beaches at French Frigate Shoals.
Jan TenBruggencate • The Honolulu Advertiser
When the voyaging canoe Hokule'a was in the Northwestern Hawaiian Islands during the past month, crew members saw lots of turtles, but nowhere were they as big or as numerous as at French Frigate Shoals.
Hawaiian green sea turtles, listed as a threatened species in the 1970s, rest on a sandbar at the eastern end of Tern Island at French Frigate Shoals. The population of nesting females there has increased from fewer than 100 in the 1970s to more than 500 in 1997.
The canoe's crew was impressed by how many there were — and even more impressed by how big they were. Many compared them to small cars.
"I thought those turtles on the beach were amazing (at Tern Island on French Frigate Shoals). I never saw so many turtles that size any place, and that was little compared to the other islands," said Ka'iulani Murphy, navigator on Hokule'a's sail.
East Island, across the lagoon, is a more important nesting area than Tern.
Many of the breeding females are close to 3 feet long from neck to tail and weigh 225 pounds or more. And they live a long time.
"We don't know how long they live, but practically, survival much past 70 years is very unlikely," said George H. Balazs, leader of the Marine Turtle Research Program at the federal Pacific Islands Fisheries Science Center in Honolulu.
Hawaiian green sea turtles are one of the great success stories in the recovery of threatened and endangered species. Green sea turtle nesting at French Frigate Shoals has climbed more or less steadily ever since the harvesting of turtles was banned in the main Hawaiian Islands in the 1970s after they were listed as a threatened species.
"This once seriously depleted stock is now well on the way to recovery," wrote Balazs and Australian researcher Milani Chaloupka in a scientific paper published last year.
Every year, new, smaller turtles are showing up at the nesting beaches at French Frigate Shoals, and genetic studies prove they are Hawaiian turtles, not recruits from elsewhere in the Pacific.
During the 1970s, in most years the number of nesting females numbered fewer than 100. During the 1990s, it was never less than 100 and often exceeded 200. In 1997, there were more than 500 nestings.
Scientists on French Frigate Shoals told Hokule'a crew members that early indications suggest that 2004 will be another year with high nesting numbers.
"It is now reasonable to conclude that the Hawaiian green turtle stock is well on the way to recovery after more than 25 years of protection of turtles and their nesting and foraging habitats in the Hawaiian archipelago," Balazs and Chaloupka wrote last year.
That doesn't mean science knows everything it needs to know about the species. French Frigate Shoals remains one of the towering mysteries: Why, when there are hundreds of apparently perfect turtle nesting beaches, does the vast majority of Hawaiian turtles swim sometimes hundreds of miles to drop their eggs into depressions on the small coral sand islands of French Frigate Shoals?
"I think the secret may well be in the current system that operates offshore, but we don't really know," Balazs said.
Other green sea turtle populations have the same pattern. There may be miles of fine sand around, but the majority of turtle nestings seem to cluster at specific traditional locations, he said.
Advertiser science writer Jan TenBruggencate was a crew member aboard Hokule'a during its 18-day voyage through the Northwestern Hawaiian Islands from Kaua'i to Kure Atoll.
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