KAPA‘A — De-listing the Hawaiian green sea turtle as an endangered species would still keep the animal protected, according to a presentation at Kapa‘a Public Library Wednesday. De-listing is required when all the criteria for recovery are met, said Don
KAPA‘A — De-listing the Hawaiian green sea turtle as an endangered species would still keep the animal protected, according to a presentation at Kapa‘a Public Library Wednesday.
De-listing is required when all the criteria for recovery are met, said Don Heacock, Kaua‘i District Aquatic Biologist at Hawai‘i Division of Aquatic Resources, Department of Land and Natural Resources. An independent review body evaluates all published literature on the topic for the International Union on the Conservation of Nature to make a determination.
“The whole purpose of the Endangered Species Act is to build populations up so that they can be sustainably managed to maintain the population,” said Heacock.
In February, the Association for Hawaiian Civic Clubs petitioned the federal government to classify the Hawaiian Green Turtle Population as a Discrete Population Segment. It would be necessary in order to de-list the turtle from the Endangered Species Act.
Heacock said that 15 years ago, the green sea turtle rivaled the bald eagle and the California gray whale as a threatened species. Today, he said the comeback of the amphibious reptile should continue exponentially.
In the 1990s he documented only a few nests on Kaua‘i. Today, he said, there are too many to keep track.
Conservative estimates have the residential green turtle population growing from less than 10,000 in the 1970s to 61,000 in 2011, he said. That includes the entire archipelago from the main islands to the Northwest.
“We are estimating that number to double within a decade to 120,000,” Heacock said.
The reasons for the decline are understood and have been addressed, he said. The ultimate solution will be to ban commercial sales of all near shore fishery resources, he said.
“We will never go back to where we were in 1972, I can guarantee you that,” Heacock said. “We will never again allow commercial or recreational hunting.”
Subsistence taking of sea turtles never ended and the state constitution requires management to keep ecosystems healthy. He said it is time to consider protecting but grandfathering elder rights, and to limit the next generation to subsistence consumption and not for commercial sale.
The increased population has more turtles nesting everywhere along the island shoreline. It is important to help control conditions now that prohibit harvesting the larger egg-laying females, and to improve habitat and the condition of the reefs, he said.
Threats
Threats to turtle populations include plastics, marine debris, including trawl netting, hooks and lines. Those threats reach Hawai‘i from across the Pacific Northwest. Heacock said more healthy turtles die after becoming entangled than from any natural predator.
“Education is a constant thing,” Heacock said. “We need to get fishers to not discard their gear. Some of it we cannot help, but we’ve all seen them take line and just throw it away.”
He said more turtles and monk seals could be saved if the state adopted a no-fault law regarding accidental hooking or netting. He said it would encourage fishers to call Dispatch instead of just cutting the line.
Prop damage from fast moving vessels that strike sea turtles as they sleep on the surface. Hawai‘i needs to follow Alaska in setting a 9 knot water speed limit to allow whales and other marine life time to get out of the way, he said.
On land, he said, four-wheelers and ATVs are a danger on the beaches. They run over turtles and they compact the dirt above nests and trap the hatchlings.
“We have to figure out something about vehicles on the beach,” Heacock said. “It is out of hand.”
Hawaiian turtle
The Hawaiian green sea turtle differs in size, life span and migratory patterns from other green sea turtles. They live around 80 years and become sexually mature at around 25 to 30 years, he said.
Green sea turtles can reach 250 to 300 pounds and are the largest of the hard-shell land turtles. They differ from tortoises that can live hundreds of years, Heacock said.
As hatchlings, the green turtles disappear out to sea where they feed on anything they find including larval fishes and jellyfish. They have incredible navigational abilities and return to shore as “new recruits” when they are about six year old and 12 to 14 inches long.
They are now herbivores and stay within distinct foraging grounds to feed on algae and seaweed around the reefs. It will take them until reaching around 26 years before sexually maturity, according to Heacock.
“Right now its taking longer with so many turtles competing for one another with food, and with intra-specific competition its probably taking them about 30 years to reach sexual maturity,” Heacock said.
In 2011, he counted 1,000 hatchlings on 19 beaches, he said.
“I didn’t get to half of them,” he added. “The egg laying female are protected and are increasing dramatically.”
According to a study from International Union for the Conservation of Nature, Heacock said the green turtle should nesting population has the capacity to double or triple.
Another NOAA 2011 study shows that more than 800 female green turtles nested on East Island of French Frigate Shoals. The larger females weighing 350 pounds or more lay up to 137 eggs. The smaller female lay around 74 eggs.
“That is called fecundity,” he said.
Female turtles move on shore to dig a trench and deposits their eggs. They covers up the mound where they hatch after 52 to 80 days, depending on temperature and amounts of rain.
The hatchlings make it to sea with a 92 to 98 percent survival rate, he said. After that there is no way to know but the numbers of nests around the island are increasing exponentially.
Adult females nest every two years, he said. That is why the population has surges followed by a decline.
“The overall trend is going up,” he said.
Area hotels have responded well to concerns that lighting aimed at the sea was attracting hatchlings that move inland rather than to the safety of the sea.
“It increases the chances of not surviving,” he said.
Another reason the Hawaiian green sea turtle population is unique in that it doesn’t mix outside the Hawaiian archipelago, he said.
The varieties of green sea turtles worldwide include the Hawks Bill, leatherneck, olive Ridley, loggerhead, Australian flatback, and Kemps rider. They have been around for 150 to 200 million years.
“They were around at the time of the dinosaurs, and obviously they were around before Kaua‘i ever broke the surface of the water,” he said.
The natural predators to hatchlings include the Ohiki crabs. The number-one sea predator is the large tiger shark.
At low tide the turtles are about quarter mile off-shore, sleeping in caves or under ledges to escape the tiger sharks. Look for them at the highest tide cycle of the month when they are visible while feeding on a red band of Tera Claudia seaweed on the reefs, he said.
Deadly virus
The deadly fibropapillomatosis is a declining threat to green sea turtles, Heacock said. The virus that causes internal and external tumors was prevalent in the 1980s and 1990s when more than half the population was infected in some areas.
The infection rate of turtles on Kaua‘i is about one percent, he said. The exceptions include a few areas around Old Koloa Landing, the Waikomo stream and Kiahuna golf course.
He said it could be coincidental discharge but NOAA Fisheries researchers found a higher prevalence of tumors near sewage treatment injection wells on Maui and on O‘ahu. It found a high level of alanine to indicate high nutrient enrichment levels of the amino acid in seaweed’s.
Prior to testing he said the seaweed growth was already considered excessive in these areas. The enrichment may be a trigger that is stressing turtles and allowing the virus to take over, he said.
“Nobody knew what the environmental stressor was,” he said. “So the stressor in this might be excess nitrogen entering coastal waters.”
Turtle fibropapillomatosis was noted on turtles as early as 1912, he said. Today, around 50 of 200 turtles near the Old Koloa Landing are infected.
Turtles average around a 1 percent infection rate on the rest of the island, he said. Studies are looking at biosides from sewage, the golf courses and other runoff on the South Shore.
Marine biologist Terry Lilley recently photographed three montipora coral varieties with a fungus-like infection at Makua (Tunnels Beach), Ha‘ena and Hanalei Bay. Heacock said people are asking but there does not appear to be a clear correlation between fibropapillomatosis and the coral disease.
A correlation does not necessarily mean cause and effect. It could be a secondary symptom of the disease, he said.
“There are no sightings of these same coral diseases in the areas where the turtle tumors are strongest,” he added.
Dr. Greta Aeby of the Hawai‘i Institute of Marine Biology identified the fungus disease about six years ago, he said. She and other coral disease specialists are looking closely at possible causes.
“I haven’t seen anything like it before,” he said. “Coral diseases aren’t well-known worldwide. It’s a new phenomenon.”
For any conservation issue people are encouraged to call Kaua‘i County Dispatch at 241-1711. They refer all calls to the appropriate enforcement and conservation group.
• Tom LaVenture, staff writer, can be reached at 245-3681 (ext. 224) or by emailing tlaventure@thegardenisland.com.
